Pat Yates, From Concept To Prototype, (must read!)

In this article, dated August 8th 2002, Pat Yates describes the development of his one-off compact .45acp which became the Detonics .45 Combat Master. An amazing read, he addresses most of the issues and solutions of designing a compact one-off .45 acp. This article touches on every aspect of the compact pistol's design. Absorbing this information should give the shooter an edge in understanding what's happening during the firing cycle, and a feel for working with that energy, a major step to mastering this little gun.

" Foreword:   This is a summary of the very early development of what eventually became the Detonics Combat Master series of compact pistols, written by the developer of the first prototype, myself.   It covers the development of the first two prototypes and the eventual sale to the Detonics limited partnership.  From that point on, Detonics devoted considerable additional effort to the refinement of the design, especially the production factors.   There is much of that part of the history of this gun that I can't
comment on, for the simple reason that I was not involved in it to any great extent after the sale to Detonics.   Consequently there are many people who contributed to the process that will not be credited here.   To them I offer my apologies in advance.  Apologies also to the ghost of John Moses Browning, on whose masterful design this was but a modest modification.  To understand this history, it is helpful to know that there was never any intent on my part to sell this design, just to build for myself a single compact .45 that met my ideas of what a compact, concealable, yet powerful handgun should be.

Background:   What became the Detonics first went on paper (sketches, not targets!) in the mid '60s while I was struggling to get a degree in mechanical engineering from the University of Florida.  I'd owned several of what was available then in the way of compact handguns and was not impressed with their reliability or power, most being in .22 short through .32 ACP with the acknowledged but seldom seen back then .32 and .380 ACP PPKs made by Walther at the upper end.  I'd been fond of 1911's for some time, enjoyed their utter reliability and trusted their power, but wanted something a good bit smaller and more friendly to carry in a hot climate.

It had long seemed to me that John Browning could have made a much more compact version of this weapon if he'd wanted to.   I assumed his thought was that there would just be too much of a penalty in operability and comfort and thus too little market for a very much smaller handgun in .45 ACP.   I wasn't concerned about market though, I simply wanted a pocketable .45 of my own.   I made up drawings from one of my ex-GI ($19.00 from the DCM as I recall) 1911-A1s and figured out that it should be possible to cut the frame and slide apart and weld them back together in a much more compact configuration and still have some hope of making the thing work.  Well, the press of school and supporting my young family, not to mention some aversion to taking a hacksaw to even a nineteen dollar .45, kept me from doing anything about it for quite a while.

Finally, Goaded into Progress:   Many years later, while working at the Explosives Corporation of America in Issaquah, Washington (yes, shocking as it may be to all the folks living there now, there was once a for-real explosives company on the western edge of the town.) with a good friend named Ken Leggett, the idea came back to life.   Ken was also a dedicated firearms enthusiast with a fondness for 1911s, and a fine engineer.  At this time (early ‘70s) Armand Swenson had chopped and channeled a few .45s down in Southern California and made them work.  Not only that, but his guns had been reviewed in several of the gun magazines and fared well.   Ken and I discussed what we could observe of Swenson's design approach from the published photos and concurred that his was a viable approach, but there were others, including the one I'd sketched over a decade earlier but done nothing with. 

Well, Ken was not the kind to let any interesting idea go untested.   I thought the short .45s were just a topic of conversation until a week or so later, when Ken showed up at work with a compact .45 still bearing file marks.   Leaving aside discussion on what kind of place we worked at, at noon Ken and I took our usual bag lunch,  four or five various .45s and ammo to our usual lunch spot at the Issaquah Rifle and Pistol Range to see how his new creation performed.  At that time I was working on a heavily modified slicked- down Commander I was determined to get .44 Mag performance out of.   Before you ask:

(a) I got close.

(b) No, the gun held up fine, I still shoot it in fact.   A 1911 will handle considerable increases in chamber pressure, it's early unlocking and the consequent slide battering that tear it up at these levels.

(c) No I won't discuss how, in today's US that would be fiscal suicide.

(d) A thinned, slick-grip Commander is damned unpleasant at these energy levels.

(e) I don’t do that anymore, a .44 Mag just makes a much better .44 Mag than a .45 ACP does, even if it is a bit bulkier.

Well, Ken's little .45 was surprisingly comfortable to shoot, but wouldn't feed at all.   It appeared to not have nearly enough room for the recoil springs it needed.  Not at all discouraged, we went back to our office and paying work, the little .45 to be pursued later.  I had an idea of a way to get a useful amount of additional spring length into the basic Browning layout, but Ken and I agreed it would be a fair amount of work.  This involved welding a block with cam projections sticking out on each side (to the full width of the frame) to the bottom of the barrel under the chamber and milling slots for them in the top of the frame above where the link lug resides in Browning’s design.   As I recall this gave almost another half-inch of room for the recoil springs as they could then run under the barrel all the way back to the end of the link lug cut.   In designing compact, powerful, auto-loading handguns, added room for a recoil spring is a prized commodity.  

That afternoon after work, I went down to Central Pawn in downtown Seattle and picked out three of their best 1911s  and 1911-A1s for a grand total of $210.00, while trying to concoct reasons for this action that might, if I presented ‘em just right, sound rational to my wife.  Before going to bed that night, I had already cut up one of the 1911s and tacked it back together.   Hand cycling it convinced me the idea was workable, but I had some careful welding, heat-treating and finishing to do before trying it out.

 Since you're reading this, you likely already know the Detonics used the perfectly conventional Browning swinging link and lug, and have figured out my idea didn't work.   What I'd neglected was the very large torque loading on the barrel caused by the angular acceleration of the bullet as it starts its spiral trip; this caused my cam lugs to bind and kept the barrel from dropping down and unlocking from the slide.   The first of several times I had to cede that John Moses was a tough act to follow.   I later added a silver-soldered longitudinal rib under the barrel cone to react some of that torque into the slide to see if that would solve the binding.   It did, and worked intermittently but the second attempt worked so well that I dropped the design altogether.

About a week later, Ken and I took it to the range along with his, which now had better springs.   If memory serves, Ken's would feed often, but not reliably; mine almost never.   That same week the second GI .45 succumbed to the hacksaw.   This time I left the link and lug area alone and added what we now call a reversed recoil spring plug in the slide.  This plug incorporated a bit of short stroke, but very stiff, spring buffering in the large diameter section that fills the frame extension and actually stops the slide.  I’d also added a guide rod that incorporated a shoe that rested on the slide stop axle where it extended on either side of the link.   This allowed a bit over an 1/8 i[PY1]nch of spring room beyond what I would have had with the Browning guide.   With triplex concentric recoil springs of very high quality wire, it worked.  The structural modifications described below are what much later was replicated in the first of the Detonics prototypes and earliest production.

(a) I cut the slide well forward of the forward locking lug recess, removed a section and welded the remainder of the forward end back on.  Then the front was shortened and squared to the finished length.  A close-fitting copper mandrel was pressed into the slide sections prior to welding to maintain alignment and control heat during the (TIG) welding.

(b) I cut the frame to remove the 'L' shaped lower aft section that carried the mainspring housing.  The first two of the three cuts involved eliminated a portion of the back section near the bottom of the of the curve of the grip safety, and the third was a continuation of the forward surface of the frame cutout under the grips.  The 'L' shaped piece was located in the new higher position with another copper mandrel replicating a slightly oversized magazine, clamped and TIG welded.  Shortening the now protruding front edge of the grip section to match and beveling the bottom of the magazine well  finished the frame mods.

(c) I machined a sleeve of stainless steel to fit over the barrel down to very near the front locking lug, tapered to clear the inner surface of the slide when the barrel is in the locked position, and with a short barrel-shaped section at the muzzle to allow the barrel to tip with very little radial clearance.  This sleeve was silver-soldered onto the barrel with an argon purge filling the bore to eliminate oxidation.

(d) Next I shortened several GI magazines by grinding away the tube where it was spot welded to the original bottom plate, cutting the tube section, re-fitting the bottom plate, then TIG welding the plate and tube together.  The magazine catch notch position was unchanged.

(e) The sear/trigger/disconnector spring was shortened from the bottom, and a new tab formed at the lower end after spot annealing.  The active length of all of the leaves was shortened appreciably  by being confined at a higher point in their length.  This had the unintended consequence of making sear, trigger and disconnector leaf tension adjustments quite sensitive.   Shortening the hammer strut and finishing the metal work completed the bulk of the modifications.

Evolution into the Detonics Design:  Over the next few months I worked on the gun when time permitted, making it into what I wanted as a very carryable .45 and addressing feeding issues.  This was in 1972 or early '73.  By late 1973 I had evolved the design into what I wanted and persuaded it to feed a few loads quite reliably.  (As any of you who own and shoot one know, even the production Detonics Combat Masters are cranky feeders.  More about this later.) 

By this time I had arrived at a set of ergonomic features for my personal .45s that I still prefer to this day.  They were incorporated in the nasty recoiling Commander mentioned earlier and this chopped and channeled compact .45.   They included the following.

(a) De-activated grip safety, with tang removed and faired to complete the contour of the frame where the tang would normally be.  The internal extension was also removed, rendering it merely a frame plug.  The lower end of the plug had a small tang similar to that on the normal grip safety but positioned to keep the plug in the retracted position.  I have always believed that the only safety one should trust on any firearm is the training of the operator.  In retrospect, given the changes in our society over the intervening quarter-century, the later designers and manufacturers of compact 1911 variants, Colt, Kimber, ParaOrdnance, et al, were prudent to keep Browning's grip safety.  The frame and plug were re-shaped by filing to move the web of the thumb up as high as possible without a total redesign.  Similarly the front of the grip was filed to a smaller radius, thinned, and the curve under the trigger guard rejoin reduced in radius to again get the gun lower in the hand; much as Colt did 25 years later with the Enhanced series.

(b) No thumb safety.  The thumb safety was replaced by a pin with a center groove very similar to that securing the mainspring housing, and a hairpin spring not unlike that used in Kahrs and Kel-Tecs today for the slide stop pin.  The left grip panel was extended up behind the slidestop/thumb safety spring tube to keep the spring in place (which was still required for the slide stop).  This followed logic identical to that for deleting the grip safety, reinforced by several practical reasons for getting rid of it which I'll discuss later, but again, I would not do that today.

(c) Grip screw bushings were shortened to just 0.050 inches in height above the frame.  This was to accommodate very thin grips.

(d) Very thin mesquite grips Acraglas'ed (Brownell Inc's most excellent product) to the frame and filling the frame cutout for very secure attachment.  These grips followed the fore and aft grip contours of the frame, covering the frame cutout for the thumb safety.  The right grip panel had a matching contour for symmetry.  Even the heads of the grip screws were reduced to about half their usual thickness and the slots re-cut to enable making the grips thinner.  The grips were fine-polished and varnished without checkering.   This was to reduce wear and tear on clothing and to reduce the tendency of sticky grips to cause the weapon to 'print' under light clothing.

(e) A different contour hammer was designed with the lower portions duplicating Browning's design but with the upper end reshaped into a more nearly vertical straight spur.  The front thumb-gripping surface was inclined about 45 degrees and finely checkered.  I've always been one of those people who gets bitten by hammer/tang pinch with a GI .45.   Eliminating the grip tang with any standard hammer made this a lot worse.  Going to a near-vertical spur eliminates the bite altogether and makes the hammer much easier to control and cock as well as lightening it a bit.  To keep the spur from being ungainly tall and hard to reach, I also stepped the back of the slide.  There were also cosmetic reasons for this, as without it my thought in looking at it was always ‘look what some damn fool did to a  perfectly good .45’.  Detonics didn't put this hammer into production, which I always regretted as it was quite practical.

(f) The aft end of the slide was stepped as close as seemed practical to the firing pin hole with an angled flat running uphill and forward an inch or so ending with a radiused step just short of the repositioned rear sight.  In combination with the new hammer shape this made for a very compact and easily cocked (and de-cocked) design.

(g) The thumb tab on the slide stop was cut back to be only very slightly raised above the blade of the stop and given very fine checkering, about 28 lpi as I recall.  The forward end of the blade was beveled to remove one more sharp edge.  The forward upper corner of the left grip panel was extended to semi-shroud the bottom of the checkered end of the slide stop to keep clothing away from it without interfering with dropping the slide.

(h) I shortened the protrusion of the magazine catch button and domed and polished it so that the tangent point of the dome was even with the flat of the frame and the peak was about 0.080 proud.  Anyone who carries without a holster will understand why.   This also saves wear and tear on clothing.  I even fitted a stiffer magazine catch spring to make it nearly impossible to inadvertently release the magazine with one's hip bone.  It's still easy enough to drop the magazine with this button when you need to, but it's never happened accidentally.

(i)  I bent the magazine tab that projects forward from the bottom of the magazine down about 20 degrees from the straight, stock confiquration.   With my hands, that was enough to get three fingers semi-comfortably on the grip.

With these mods the little .45 was about as thin and compact as I thought I could make it and still keep it reliable and bearable to shoot.   With the very thin, slick grips and hot loads, it is quite noticeably harsher in recoil than a production Detonics (when much later I had one to compare), or a stock 1911 or Commander, but it was also a good bit easier to conceal.  Every aspect of this gun was biased toward practical carry, not comfort in shooting, fast magazine changes, or the current fad of cocked and locked carry.   Toward this last, I concede that if the only measure is time to prepare the weapon for the first shot, cocked and locked will have a modest edge.   My opinion though has always been that during the presentation of the gun from wherever it's carried to alignment with the target there was enough time to cock the hammer several times over before the gun is approaching firing alignment.   I also have a lot more faith in the inertial firing pin with the hammer down than I do in thumb safeties of any design when the gun is being carried.  

To that end I always used heavier firing pin springs to raise the threshold for firing on dropping the weapon.  In some limited tests I performed with a junk .45 about this same time frame, I found that an unloaded but primed round would not fire until the weapon was dropped muzzle-down on a concrete surface from more than eight feet.   No other impact orientation produced any primer firings at all, and only the muzzle down impacts produced any visible primer dents.  With the Titanium firing pins now on the market, this should be increased, but I have not performed the test with the lighter pin.   I also felt that a  person clumsy enough to replicate this in real life deserves to be surprised, and shouldn't be carrying a gun in the first place.   Youth is a wonderful, but sometimes scary experience isn't it? 

I shot and tweaked this gun intermittently for several years and was quite confident of it's function with certain loads.   The two that it was truly reliable with were a hot handload using the Hensley and Gibbs #68 200 grain semi-wadcutter cast of linotype (about 185 grains in that alloy), and the Winchester-Western 185 grain Silvertip.   Accuracy was surprisingly good in spite of the short sight radius. 

The Transition to a Detonics:  Along about late 1973 or very early 1974, EXCOA was ‘downsizing’ as we say now, and several of the former managers, Mike Maes and Sid Woodcock among them, had left and formed a new company called Detonics.   Contrary to what many may think, the founding intent of the company and much of their business had nothing whatever to do with guns; their specialty was, as EXCOA's had been, specialty explosives and explosive systems, the development of which was just not profitable enough for the big companies.  Sid had watched the evolution of this little gun, shot it a fair amount, and thought it could be marketed.  

I, displaying my dazzling business acumen and all-around good sense, of course told him he was crazy.  Only a tiny number of folks could be so mal-adjusted as to want so much power in such a small package; plus, since Ken and I both now had one, even that number had to be cut by at least half.   With 25 years of hindsight, and the now obvious and continuing trend toward powerful but compact handguns, it's pretty clear just how accurate that prediction was.  I sometimes wonder if Armand Swenson had any idea at the time what he was starting.

Well, pretty soon the downsizing at EXCOA had gotten to me too, and I took a wonderful job designing missile safe and arm and warhead initiation systems with the Naval Weapons Center at China Lake, California.  (We called it the People's Republic of California even back then in '74.  How little did we know.)   During the time I was wrapping up my projects at EXCOA and getting ready to move to NWC, Sid finally convinced me the little .45 was worth patenting and producing, so I sold the rights to Detonics, helped them fight through the patent flail, prepared for them a set of engineering drawings of the complete gun and offered whatever assistance I could manage in getting it into production.  I lent them the prototype for a year or so, with my permission to see if they could break it or wear it out.  Sid told me years later when they returned it they'd put over 20,000 rounds through the beast.   It's still functional, though my slide weld, never re-heat treated, is beginning to show signs of stretching a bit.  That's not from pressure, the force from chamber pressure doesn't show up there, but the pounding of the short-stroke slide running into the frame.

I should add here that when they received the prototype, the reversed recoil spring plug/integral buffer spring had just broken the second or third version I'd made.   I just couldn't control the heat treat well enough to make a good machined spring in my garage.  The prototype they got had a solid plug, very much like their production guns kept throughout.  If it had had a working example of the spring buffer, I doubt the slide would have been at all distressed by 20,000 rounds.  I always regretted they didn't get that buffer into production too; it was not a bad design, improved the cycling and feeding a bit and the perceived recoil a lot.

I took some modest up-front cash payment from the company, but in place of per unit payments for the royalties, I took guns at their best distributor pricing.  This was probably the only smart thing I did in the entire business portion of the arrangement, and even then I refused their first offer of royalty per gun produced and came back with a counter-offer less than what they were offering.  I was still convinced they were going to fold promptly and I didn't want to be part of their burden.

Detonics put a couple of pretty damn good engineers on the job of tooling up and 'production engineering' the gun.  Remember, I designed it with the intent of building one only, mine, and I'd concentrated on modifying Brownings original and widely available parts to suit my needs.   I didn't really have too much to do with this process, and at this point can't even remember most of their names.  At some point in the production development though I remember they brought Roland Franzen, also a friend and EXCOA refugee and very good designer in on it.  The team certainly did a fine job of it.  The very first guns were made pretty much just as I'd made the prototype, from various 1911 clones cut apart and welded back together.   I think this represented more of a pre-production prototype phase in today's parlance as there seem to be very few of those in circulation.  Quite soon though they had investment cast frames and slides made to the Detonics dimensions and materials, plus the small bits that weren't direct drop-ins from the 1911, coming from various shops.  I have several of the welded-up early guns taken as offsets against royalties for my collection and have to say the new made from scratch frames and slides were a vast improvement.  The first of the investment cast frames had a molding error that resulted in the magazine well being over a degree mis-positioned.  These had amazing feeding problems for such a modest error; indication of the criticality of feeding dynamics with such a short, fast cycle.   I don't know if any of these frames made it out of the factory or not.

There were a fair number of small things they did not incorporate from the prototype, for a mix of cosmetic, production and liability-avoidance reasons.   This list included:

(a)    The more upright hammer spur.  (Yes, the production Detonics Combat Master hammer still bites me, though not often, and not with immediate bloodshed.)

(b)   The spring buffer integral to the recoil spring plug.

(c)    The deletion of the thumb safety.  (Very good move on their part.)

(d)   The very thin grips, thinned grip screws and grip screw bushings.  (Too bad on this one, it makes a considerable difference.)

(e)    The re-contouring of the grip area of the frame.  (Small change, but significant to folks with small hands.)

(f)     Triplex recoil springs.  (Duplex springing and just a smidgen longer slide was made to work just fine, though some guns are seen with triplex springs.)

(g)    The shortened, rounded magazine catch button.

Additionally, they added some features not in the original design.

(a)    The cross-hole in the guide rod as a take-down aid, followed a bit later by the captive recoil spring assembly caged by the Allen head cap screw.  Nice touch.

(b)   The semi-adjustable sights.

(c)    The 'full-magazine indicator'.  (Embarrassed I didn't think of that one as it allowed an unmodified standard follower to fit.)

It wasn’t long before they'd started work on expanding the family to include the stainless steel guns.  I can claim very little credit for their choices of materials here, though I’d like to.  The alloys and heat treats they chose were superbly selected to avoid the stainless-to-stainless galling that had plagued the early stainless guns (and some to this day).  Most of the guns I ordered from the factory in lieu of royalties were stainless Combat Masters, but with a few of the early welded up guns, several late blued examples, and one satin nickel finished 'I' series gun as development examples.   I also took one Scoremaster in payment though I had nothing to do with its design.   It remains one of my favorite .45s even today and is still extremely accurate and reliable. 

Most of these I sold.   Some were sold as-issued, around a half-dozen were modified to the configuration described above of the prototype (but with a partially hidden thumb safety!), and sold at much higher prices.  One of these latter was engraved and presented to King Hussein of Jordan by the Los Angeles Jordanian consulate staff on the occasion of a visit there in the mid '70's.  A few of the custom versions were kitted out with custom leather by Alessi with a matching Tanto  and sheath (I used to make knives also) on the off-side.   The two of these I sold went for truly amazing prices.  I priced these sets to avoid selling them, but displayed them on my table at the L.A. Great Western Gun and Knife Show, and had to part with them when someone paid it..  (The Great Western is now another deeply missed artifact of our past here in California.)  A few of the custom versions were given away to friends and family, and one I retain.

I spoke earlier about the reasons for deleting the thumb safety from my personal gun, the Detonics prototype and the slicked down Commander.   There were several reasons, wear and tear on clothing and hide were one, a lack of trust in them staying in the desired position another (less of a concern for folks who carry in holsters), but a lesson from Sid Woodcock was the deciding factor.  With most folk’s grip on any of the 1911 clones, the thumb safety is the focal point of one disarming technique that Sid proved could be executed from startling distances by a well-upholstered, not-quite geriatric gentleman of experience.  I think I still owe him several beers on that bet.

I also promised to say more about the feeding issues of the Detonics.  By trial and error, and a bit of intuition, I'd made my prototype feed reliably with the two loads I was most interested in.   This limitation of two loads was less than desirable for a production gun though.   I photographed my prototype, one of the early production guns and an unmodified 1911 during the recoil/feed cycle at 3,000 frames per second with the assistance of a retired photo technician from the Naval Warfare Center and a many-times-rebuilt surplus Fastex camera.  What I learned was not too surprising.  

Given the very much shorter slide stroke of these guns and the lighter slide, the slide has a good bit higher velocity remaining when it slams into the frame compared to a full- sized 1911 or clone.  With the stiffer recoil springing, it also has considerably higher velocity throughout its trip back to battery.  This leads to two main consequences.  First, when the magazine is full, the top round has trouble making it all the way up to full contact with the feed lips before the breech face of the slide impacts the case head.   Fairly often, especially with ammunition using heavier bullets, the top round will be noticeably nose-down at this point.  The impact of the breech face at the upper edge of the base of the round tends to drive the nose even further down as the point of impact is above the center of mass of the round, frequently causing it to jam into the magazine well just below the feed ramp.  Lighter bullets seemed to avoid this and the case was usually in contact with the lips of the magazine when the round started forward.  Bullet shapes with a smaller diameter meplat at the nose, like the H&G #68, were also more resistant to feeding problems here.

The other observation was that the round very often bounced from the slide face into the chamber well ahead of the breech face.  This didn't seem to be related to the feed failures during the limited testing that I could afford, but it did indicate the dynamics were a bit more frenzied than one would expect, and in fact with the few films made of the 1911, it was not observed at all there.  At this point I no longer remember the actual slide velocity profiles of the three guns with the several loads tried, but do recall the prototype and an early production Detonics peak slide velocities were roughly half again those of the 1911 with the same loads.  This cannot be accounted for by just the lighter slide mass if the impulse delivered to it is the same.  The Detonics and the prototype's slide just aren't that much lighter. The smaller gun's slide unlocked earlier, not much, but enough to increase slide velocity quite a bit.   The 1911 slide was not only moving much slower when it impacted the frame, it rebounded forward to strip the fresh round much more slowly.  This appeared to be important for two reasons.  It allowed the magazine spring to always get the top round up against the feed lips, and it eliminated the frequent nose-down attitude of the top round with the heavier bullets.   I built a Tungsten barrel sleeve to increase the recoiling mass prior to unlocking a bit, but by the time I'd gotten it done, it was pretty clear this was not an acceptable production solution, so I never tried it. 

I spent a considerable amount of time working with various spring and buffer combinations trying to slow the slide's return to battery enough to get reliable feeding with all likely ammo.  Straight spring buffering, as I'd been using in the prototype didn't help at all with this aspect, though it did ease the slide's impact against the frame.  Elastomeric buffering at the aft end of the recoil spring as Bill Wilson used later seemed to help, but with the very thin section possible in the Detonics geometry (much less than with the 1911 and clones) and the lack of any easy way to retain it, I couldn't make it survive more than a few dozen shots.   I tried a thinner flange on the recoil spring plug and a square-section ring of rubberized fabric between the flange and the aft end of the spring housing portion of the slide, but couldn't keep it from bulging out and scrubbing on the frame dust cover and hanging up the slide on the return to battery.

The approach that came closest to solving the spring and buffering issues as well as being the most interesting was the use of a volute spring.   Visualize a thin ribbon of stainless spring steel of around 0.010 thickness, cut in the shape of a parallelogram maybe 0.30 wide in the uniform width middle section, something like 18 inches long, and tapering to around 0.20 wide at each end. 
Then spiral wrap it around a mandrel (a really fun task if your collection of whips and chains is already complete and you're bored) and roll it into staying in the spiral configuration.  What you'd have at this point is a spring with a highly non-linear rate.   These things are terribly complex to design and even worse to fabricate, but can allow not only the needed very high total energy absorption and volumetric energy density with the very stiff final rate just before the slide hits the frame, but if done just right, incorporate a considerable amount of friction in that last bit of compression travel.  The problems were:  I couldn't find any spring shop willing to make it, and the friction changed greatly with lubrication and fouling.   In thirty years of design engineering since then, I've not found it too hard to resist designing, much less making, another one.

The Connection with Pyrodex:  This is certainly a peripheral connection, but I think it's interesting, so here it is.  One of the other designers at EXCOA in this period was Dan Pawlak, my best friend.  Dan was a remarkable young man in many regards, plus having a startling resemblance to the actor Tom Selleck who later became so successful.  Everyone I knew who had known Dan was somewhat disconcerted nearly a decade later with Tom Selleck's first appearance as the lead character in the Hawaiian detective TV series, 'Magnum, PI', the resemblance was that strong.  While no slouch at mechanical design, Dan was more interested in the chemistry of pyrotechnics and explosives.  The stubby barrel of this little .45 produced serious muzzle flash with heavy loads at night; more than enough to be disruptive of the shooter's dark-adapted vision. 

With his interest and knowledge of pyrotechnics, Dan promptly suggested adding a tiny amount of a common chemical (0.2 grains as I recall, and no, I'm not going to say what it was) to the load to control the muzzle flash.   The effect was pronounced.   Loads that otherwise produced a white-orange fireball over a foot long and about the same diameter yielded a golf-ball sized blue-white spark of much shorter duration with the addition.   Dan tested the load extensively for internal ballistic performance with a pressure barrel/receiver he'd made up and which we were using to push for the magnum performance in the .45 Commander that I mentioned earlier.   Using piezo-resistive transducers tapped into the chamber and strain gages on the barrel in several places, we convinced ourselves that the load was safe and practical for some time after assembly, but never attempted any long-term stability evaluations with it, thus the absence of any more detail on it.

But what's the connection with Pyrodex?   Dan was the inventor of that first commercially successful black powder substitute.   A few years after leaving EXCOA, Dan developed the black powder substitute, built a small scale production facility in an unused explosives plant he leased from EXCOA, performed all the extensive safety testing and got Department of Transportation approval to ship the material by common carrier.   Not long after getting it into production in three grades, pistol, rifle and cannon (Dan was a serious black powder cannon and display fireworks buff), he sold the rights to Bruce Hodgdon and continued to work on further refinement of the product as well as producing it for continued testing and initial distribution while Hodgdon got their much larger facility up and running in Kansas.   Dan and several of his workers were killed in an explosion and fire at the leased facility a few miles east of Issaquah in late 1975 or early 1976 if I remember the date.  The subsequent investigation proved it was an equipment failure, not a problem with the product.

Well, that's my part of the development of the Detonics.  If you own one of these little guns, I hope it adds to your enjoyment of it to know a bit about how it came to be."

Pat

Last Modified on April 8, 2002
aalbert@biggerhammer.net