The Sixgun Journal Repatriated Ruger GP

The Sixgun Journal

The Repatriated Ruger GP-100

photos and digital editing by Peggi Sargent.

Ruger GP-100 .357 Magnum, 3" barrel.

My introduction to Ruger's double-action revolvers came about 1974, in the form of a 4" stainless steel Security Six, in .357 Magnum. My uses for a handgun were purely recreational back then, and that little .357 accompanied me on many a long hike back to a secluded lake that had some of the finest bass fishing in the free world. It was a dandy sidearm, and it accounted for numerous small game animals and several of the poisonous snakes that seemed predisposed to interfere with my youthful adventures. It's accuracy with .38 wad-cutters was sufficient to convince me that carrying a .22 target pistol on woods forays was more an affectation, than a necessity. Having .357 power on demand was just icing on the cake.

Too bad "eighteen" doesn't last forever. It wasn't long before I was packing a pistol for more serious purposes, and trying to satisfy my handgun addictions on a patrolman's wages. Soon another Ruger .357 found it's way into my holster, and this time it was a blue 4" Speed-Six. Skeeter Skelton had once postulated that a pair of these revolvers with 4" heavy barrels would make a prudent man about as well armed as any pistolero could hope to be. Mr. Skelton was one of the most credible men who ever penned a line on the subjects of law enforcement or handguns, and it was a dark day for the students of both fields when we lost him in 1988. His gift of practical wisdom was not wasted on me.

While I couldn't very well get away with wearing twin sixguns on my uniform, I could sure pack one of them. I'd just have to shoot it about twice as well to make up for having only one, I reckoned. I had been lucky with my new Ruger, and its fixed sights were dead on the button as it left the factory. It would splatter a gallon jug out to about 75 paces with Federal 125 grain hollow-point magnums, but still printed 148-grain wad-cutters close enough to pot a squirrel at 20. I shot this gun a lot, and eventually traded it for something that I needed less- but thought I wanted more. Well, you would always be able to order a new, blue Ruger Speed Six, wouldn't you? Huh? They did WHAT?!?! I probably have at least one bad knee from kicking myself in the rear end over that trade for the past 20 years…

Ruger's decision to discontinue the Speed/Service/Security Six line in the mid-80's caught me "flat-footed"- a condition not entirely unknown to policemen in any event. I viewed the new replacement (blandly named "GP-100") with a jaundiced eye. It was heavier than my old Speed-Six for no good reason I could think of, and it's looks did not impress me in the least. The first one I handled shot OK, but felt like it had a garage-door spring powering the mechanism. It's grips were downright homely, and there wasn't even a grip frame under there to bolt a nice set of stags onto!

The one redeeming quality of the GP was its front locking lug, which stabilizes the front of the cylinder at the yoke instead of the ejector rod. I had gotten acquainted with the .44 Redhawk, and was thoroughly convinced that it was the strongest D/A sixgun on the market. I had also seen a good number of S&W's with bent ejector rods over the years, a condition which invites problems with free cylinder rotation and front lock-up. A relative soon acquired another GP-100, and his specimen proved very accurate; it's action was also notably better than the first one I had handled. While not a thing of beauty, that rubber grip was the most comfortable I had ever used with full-snort .357 Magnum loads. It still seemed unnecessarily heavy to me, but I had to admit that it looked capable of wearing out most shooters, well before the opposite event occurred. I began thinking that one of these with a slender barrel and fixed sights would be about the ideal hard-use .357 wheel-gun. Meanwhile, time was coldly marching on- and decent 4" Speed-Sixes were getting harder and harder to find.

Still, I held off buying a GP-100 for a long time. Law enforcement had switched to the auto-pistol in droves, not long after it was introduced. My own duty holsters were generally occupied by a good 1911, or a 4" S&W .44 when I could get away with it. The old salts who taught me the job had used the term "rubber gun squad" as an insult, and I wanted no part of the polymer-poppers. I was eventually assigned to a plain-clothes position, and again enjoyed considerable latitude in my choice of weapons. A compact .357 revolver went back on my list of "bargains to watch for", and a fixed-sight GP-100 with a 3" barrel was pretty high up on that list. The only negative considerations were that all of them that I had seen wore a heavy, full-lugged barrel, and their retail price was about twice what I had paid for by beloved Speed-Six so long ago.

Well, good things don't come cheap- unless you're lucky, and maybe willing to get your hands a little dirty to make the most of a bargain.

While 'treasure hunting' at a local gun shop, I noticed a stainless variation of the GP-100 I had never handled before. It was a .357 with fixed sights and a 3" barrel, but with the ejector shroud no longer than necessary to protect that vital appendage. After an appropriate diversionary examination of things I wasn't really interested in buying, I asked to see the little revolver. I noted that in addition to the lighter barrel profile, it also had the shortest grip I had ever seen on one of these guns. Hefting it next to the competition's service-grade .357 revealed that any practical weight difference was non-existent. The abbreviated grip frame of the GP-100 evidently reduces the overall weight of the gun significantly. The barrel-cylinder gap looked to be about .005", and remained constant throughout the full rotation. The cylinder itself showed no drag line, and it locked up tightly with no end play. Firing pin protrusion seemed sufficient for reliable ignition. The bore was perfect, and the double-action mechanism was actually smooth and light!

While the finish bore a few minor blemishes, the recoil shield indicated that revolver had actually been fired very little in its lifetime. The left side of the frame bore an importers marks from Century Arms International; this gun had evidently seen foreign service, and had found it's way back stateside. The electric-penciled "C.A.I." mark and a dinged front sight provided proper points for haggling the price, and after negotiations the GP-100 was mine for less than half of what a new one would have cost me.

I ran the little GP out that evening for a quick function-check, and found it to be a natural pointer, possessing of decent accuracy. It was a little hard to tell at first because while the sights were pretty close for windage, the front was obviously too short, causing the gun to shoot about 7" high at 25 yards. Moving in for some fast D/A work revealed that the sight regulation was "close enough for government work" out to 15 yards or so. But that fast D/A work also revealed another problem- occasional misfires. This would have to be corrected, because absolute reliability should be the first requirement for any carry gun.

Looking into the 'misfire' problem revealed a few things, and provided some time and incentive to correct the little revolver's shortcomings. The first thing I did was get on Ruger's website, and check the serial number against the dates of manufacture. This excellent resource may be found on the Internet at www.ruger-firearms.com/Firearms/SE-CalSerialHistory.html and it indicated that my GP-100 was made in 1989. This would make the mainspring at least 14 years old, assuming that it wasn't made when the model was first introduced in 1986. A new mainspring would doubtless improve reliability in fast D/A fire. The second thing I did was to call Ruger, and request their factory specs on front sight height and firing pin protrusion. They were quite helpful in establishing that the front sight for the 3" model should stand .343" above the rib; a full .1" higher than the battered old sight on my gun. A couple of spare sights and pins were ordered for less than $12.00 shipped. Ruger was a little less candid about the factory specs for firing pin protrusion, and after some research on that subject I am beginning to understand why. I discovered that insufficient firing pin protrusion is a common problem with their Redhawk series- although this is the first Ruger D/A I had ever owned, that suffered from it. I also learned that custom gunsmith Hamilton Bowen manufactures an "extra-length" Ruger D/A firing pin, and now installs it as a standard component of all the Redhawk conversions that leave his workbench. This is particularly noteworthy considering that Bowen specializes in building big-bore Rugers which are likely to be employed as defensive implements in 'bear country.' This would definitely not be the place to be having a misfire.

Brownells, on the other hand, didn't have any problem at all telling me that the industry standard for firing pin protrusion on revolvers was .050-055 inches. It was time to grab a set of micrometers and get to the heart of this matter. Luckily, this revolver's short barrel length allowed me to use my 6" micrometer to take a direct measurement from the muzzle, to both the protruding firing pin and the standing face of the breech.

The Sixgun Journal

Putting the micrometers to good use: checking firing pin protrusion.

The original firing pin protrusion checked at .036 inches. A careful refitting of the transfer bar and hammer nose got it up to .040", while actual pin reach (pin depressed directly against frame with a flat object) maxed out at .045". CCI primers in resized brass were then run through the gun D/A, as fast as the action could be cycled- 6 shots in a shade under 2 seconds. Ignition was now 100%, but with some primers still showing light indentations.

Things were obviously better, but I wasn't about to settle for anything less than 100% reliability- with some room to spare. I looked closely at the channel in the frame where the hammer rests. Casting marks were still clearly visible, and by depressing the pin to it's full depth (below 'flush') it was apparent that there was another .005-.006 that could be gained by relieving the frame in that location. The part of the pin engaged by the transfer bar was blackened with a fine-point marker, so as to immediately show when the frame had been relieved to the limit of the pin's rearward extension. The pin was then fully depressed and retained in the forward position by clamping a reloading die lock ring onto its nose. Judicious work with a safe-edge file brought about the desired results, and after a second re-fitting of the hammer nose and transfer bar, firing pin protrusion now stood at a dead .050". In addition to finally being on US soil again, the little gun was also finally up to industry specifications.

The new front sight had been received and installed while all of this was underway, and I was anxious to see what improvements, if any, my efforts had produced. I took the GP out for a short function-check, using the old, light mainspring that had been in the gun when it had the initial problems.

To make a long story short, bringing the firing pin protrusion up to .050" made all the difference in the world. I couldn't shoot the thing fast enough to make it miss a primer, and the indentations are now nearly as deep in fast D/A as they had been in single-action mode before. I am still going to replace the 14-year old mainspring with a new, stock Ruger part. Needless to say I didn't buy this little revolver to shoot silhouette matches with. But with the reliability issues finally resolved, it was time to find out if this little .357 would shoot.

This might be a good time to address the issue of what constitutes acceptable accuracy in a general-use sidearm. I have noticed a trend by certain gun-writers in recent years, to applaud what I would consider pretty sorry accuracy from handguns that cost most of us a couple of weeks wages. I read about this purported "4.5 at 25" yards accuracy standard for service pistols, and it annoys the hell out of me. For those of you who are too young to recall, this nonsense got started when law enforcement switched to high-capacity autoloaders. Some of these guns, particularly some of the early "double-action only" autos, were more difficult to hit with than any D/A revolver. Scores went down, and law enforcement firearms proficiency standards got lowered because it was easier and cheaper than training- and more politically expedient than holding people to meaningful requirements. This was the dawning of the "spray & pray" era, which sadly continues to this day.

The "4.5 at 25" yards standard is ludicrous. I have a box-stock Sig P-220 that has produced numerous groups under four inches at twice that distance. I had a stock Colt 1991-A1 Commander that would routinely shoot into 3.5" at 50 yards, with Federal 230 grain Hydra-Shoks.

So let me get this off my chest- any decent medium or full-size (4" barrel or longer) service handgun, auto or revolver, should shoot into 2.5" at 25 yards with good ammunition from the bench. A really good one will get down around an 1.5". This means all five shots from a auto, or all six shots from a revolver. No, we're not counting the best three of five. We are counting ALL of them, for the overall group. If you screwed up the first group, then shoot another one. It happens to all of us. If the gun screwed it up, then we have a problem. If you are regularly getting 5 in a nice cluster with one flyer- we're getting there. When that happens, the gun is probably out-shooting the shooter. I'll make a little allowance for the shorter guns, but they better keep their shots in 3" at 25 yards if they want a place in my stable. Sorry, but "them's the rules".

So we will establish from the outset that my expectations are maybe a little higher than some other folks. I learned a long time ago that when somebody else gets to start your fights, they'll hardly ever ask if you're ready, sighted in, or how much of their anatomy you'd like to be able to shoot at. Lord Alfred Douglas will not be officiating at these events, and you had better be able to shoot up to the hand you are being dealt. A powerful, accurate, and well-regulated handgun is a comforting thing to have- and one less variable to have worry about when the "balloon goes up".

The GP snub didn't embarrass itself. This belligerent-looking little sixgun showed promise right from the outset, grouping almost anything under 3" at 25 yards. The new front sight corrected the elevation perfectly, but the gun was now shooting about 4" to the left at the aforementioned distance. This wasn't real bad- but it was not something to be ignored, either. More on that later...

The first set of reloads tried used Winchester 231 powder. This is perhaps the finest powder extant for the .45 auto, and it gave a fair account of itself in the .357. Best accuracy came with Winchester's 158 grain SJHP- but the Sierra 125 JHP was not far behind. Lead bullets with W-231 was another story. Even a light, 4.5 grain charge of W-231 with a hardcast 158 grain SWC leaded badly, and refused to group better than 4.5" at 25yards.

I tried to remind myself that I was shooting a 3" fixed-sight carry gun here, and not a 6" target revolver- but it just didn't work. The memory of that sweet-shootin' old Speed-Six still haunted me. I also wanted more power than the W231 loads offered, without a sacrifice in accuracy. The GP-100 was designed for a diet of full loads. It needed to shoot to the sights with both a full-power jacketed bullet load or two, and an accurate small-game load as well. The vertical dispersion between the 125 and 158 grain loads was just under 3" at 25 yards. This was close enough for me.

I decided to try to find a single powder that would handle the full range of applications I had in mind for this sixgun. I knew from experience that W-296 and Hodgdon's H-110 are near-perfect for heavy loads in longer barrels, and Universal Clays does yeoman service for light to moderate loads using cast bullets. While I was tempted to stick with my old stand-bys, a lot of experimentation had gone into this project already Perusal of the various powder companies' offerings provided a lot of entertainment, but in the end I settled on Hodgdon's HS-6. It looked like this powder would handle everything from light loads, right on up to heavy loads generating within 150 fps or so of what is possible with the true magnum handgun powders. I load the .44 magnum as well as the .357, and entirely serviceable hunting loads were listed for it using this powder as well.

The results of my initial efforts at reloading for the GP-100 are listed below. Be advised that they are all maximum loads, and that you should start lower and work your way up, watching for pressure signs as you go. They may react differently in your gun than they did in mine.

Bullet	Charge	Published Velocity (10" barrel)	Group for six shots at 25 yards
Win. 158/SJHP	6.9 g. W-231	1260 fps	1 ½"
Sierra 125 JHC	8.1 g. W-231	1460 fps	2 "
Win. 158/SJHP	9.5 g. HS-6	1375 fps	2 5/8"
Sierra 125 JHC	10.9 g HS-6	1629 fps	2 5/8"

Trying a different powder turned out to be a good idea. The HS-6 load using the Sierra 125 JHC is presumably still going well over 1300 fps, even from the abbreviated tube of the GP-100. They certainly shot well enough, with 5 of the 6 shots going into 1 3/8". The Winchester 158 SJHP load using HS-6 is probably still doing around 1200 fps; The GP-100 also planted 5 of the 6 shots in that group into 1 3/8". This little revolver was shooting better than I could hold it- and pretty close to the sights, at that.

Decent 25 yard "snub-nose" accuracy-125 grain

Sierra load highlighted in yellow;

158 grain load highlighted in blue.

Close is just fine for a "belly gun", but the little GP was intended to be a woods companion as well. A "woods gun" should be capable of taking small game to 25 yards, and in order to accomplish this the sights need to dead-on. There is a common misconception with fixed-sight handguns, that you are stuck with the factory sight regulation- and that you simply must have adjustable sights if you expect to be able to make precise shots on anything smaller than a refrigerator at 50 feet. Another misconception is that the consumer is limited to either sending the gun back to the factory, or enlisting the services of a gunsmith to correct this malady. I have nothing against gunsmiths, and I'll be the first to proclaim that I am not worthy of that lofty title. I am simply a shooter who has determined to solve most of his own gun-related problems.

Correcting this condition requires that you know which way the barrel screws into the frame, and which way you need to move the front sight in order to correct the windage error. Correction is accomplished by moving the front sight towards the windage error, as seen from the shooter's perspective. On this particular gun, the barrel screws into the frame with conventional right-hand threads. This would simply mean turning the barrel just a little more tightly into the frame.

Barrel screws in to the right, moving the front sight to the left

(as seen from the rear) in the process.

The sixty-four dollar question was just how much to move it, and how to measure the movement as it was accomplished, to avoid going too far.

Close examination the stripped frame revealed that a baseline measurement could be taken from the left side of the frame, to the left underside of the ejector shroud. This provided two relatively square surfaces from which to obtain the measurements, and a means to determine how far the barrel had been turned once that operation was underway. Several readings determined that .090" was the original offset between these surfaces, and after careful consideration of the sight radius and the amount of correction required, an end measurement of .095" was set as a goal. This would result in moving the front sight slightly more than that distance to the left, as its rotational axis is slightly further out from the centerline of the bore.

Getting a baseline reading on barrel position, using the frame

and ejector shroud as reference points.

It requires neither a degree in physics nor rocket science to grasp the notion that a magnum revolver's barrel must be screwed in tight when it leaves the factory. Loads generating nearly 40,000 CUP might otherwise loosen it from the frame, perhaps causing embarrassment for the shooter at an inopportune moment. It would obviously require some carefully-applied torque to get the job done.

If you are having visions of large, padded bench vises and hickory hammer handles about now, you're not far from correct. This very method has worked well for me in the past, and I'll probably employ it again someday when there is no better means available. This time it wasn't necessary. Anyone who has ever had a flat tire fixed, understands that impact is one of the most effective means of moving tight, threaded fixtures on a rotational axis. Since Ruger thoughtfully provided me with an ejector shroud built like a battleship fitting, there was a suitable point on that axis for applying some impact. I could spend another hundred words explaining the process, but the photo aptly illustrates what was done. A short section of 2x4 was used to support the frame, and an oak bench block was used to transfer the hammer blow to the ejector shroud.

Setting up for the barrel adjustment.

The entire process required about eight good licks with a small ball-peen hammer, stopping to take measurements about four times along the way.

Impact-turning of the barrel in the frame.

When the barrel had been turned in .005" the gun was re-assembled and another trip to the range was made.

The results were gratifying. I had about 25 rounds of assorted 158 grain SWC's in the range bag, and it wasn't much work to find a few clay birds and old beverage cans scattered around the local public range. The majority of these rounds were put to use on these targets double-action at 25 yards, using a 6 o'clock hole to account for the 3" high point of impact at that distance. Not a single target survived the onslaught, and the cans were thoroughly riddled at the end of 12 rounds.

The first load tried on paper was the HS-6/Sierra 125 JHC load listed in the chart. I concentrated intensely upon keeping exactly an equal amount of light on either side of the front sight when I was shooting these, and frankly wasn't paying much attention to elevation in the process. This resulted in some vertical stringing, and it came as no surprise. The next six shots were the HS-6/Winchester 158 SJHP load, and I watched the top of the front sight a little more carefully this time. I was rewarded with 5 of the six inside the 3" Birchwood-Casey "Target Spot", with a single yanked flyer spoiling that group to 3.75".

On a lark, I had assembled a few reloads using 7.0 grains of HS-6, and Hornady's 158 grain swaged, wadcutter hollow-point. I had picked the load at random, and later saw it listed in Mic McPherson's excellent 3rd edition of Metallic Cartridge Reloading. It was said to produce 1100 fps from the 7" test barrel, so I had no worries that would be sufficient in power for the "woods" load. I did harbor some concerns that it might lead badly at that velocity, and wondered if it would shoot up to standards- or close to the sights.

I worried for nothing, because five of them grouped inside 2 1/4"- and right on top of the front sight! I again managed to throw a flyer, rendering the total measurement 3 3/4." I will accept the blame for that one as well.

Results worth the effort; 10 of 12 shots at 25 yards, using both loads, print within 1" of the target's centerline.

I'm not crying too hard. My 3" GP-100 has proven it's ability to group under 2 1/2" at 25 yards with loads it likes, and it routinely plants 5 of the 6 under an inch and a half when I am holding up my end of the deal. It now prints its shots dead on top of the front sight at that distance. I have plinked with it enough out to 50 yards that I'm convinced that any coyote, two or four legged, had better have his accounts settled if he affords me a shot at that distance. It carries unobtrusively, it hits hard, and after a little tune-up I have the utmost confidence in it. The price was right, and the actual investment in parts was under $10.00. You can't ask for much more than that.

Once in a while, I still see a blue, 4" Ruger Speed-Six on the internet auctions, and I fondly remember the old gun I carried back in the early 80's. But I don't miss it quite as bad as I used to.

Skeeter Skelton was, above all else, a practical man- and I think Skeeter would understand.