GP100 In Local IDPA Match

[JonInWA]

For the second time this month, I campaigned my 4" blued GP100 in an IDPA match. As I've discussed previously her on p-f, mine has been extensively worked on by Chris Peters some 20 years ago, and his work (and the GP100 itself) has withstood the tests of time an use well. Despite the work, the parameters were such that the GP still qualifies for Stock Service Revolver.

I had previously been running the gun with a Wolff 11# hammerspring (which extensive empirical testing and use provided 100% ignition with all factory ammunition used {Federal, Seller & Bellot, Winchester, Fiochicci, CCI, Herter, and PMC). In reading some reviews of ISMI chrome silicon springs, I decided to try their GP100 set. In discussions with Marc Cosat, the owner of ISMI, the ISMI trigger return/trigger guard latch spring is some 10% heavier than the OEM Ruger, for a crisper trigger return, while the hammer spring is at approximately 12#, which is the generally recommended weight for "all use" primers and cartridges.

Prior to the first match, immediately after installing the ISMI springs, I failed to test the gun prior to the match-hind-sight being 20-20, not a bright idea... When shooting the match, I immediately had ignition issues with DA firing, and in fact was only able to achieve ignition using SA-and not 100% even in SA. The cartridges used were PMC Bronze, Federal Champion, and Herter, all factory new 158 gr .357 magnum. Immediately after the match I left a VM for Marc Cosasat, and we had a good discussion; the upshot is that he's never encountered light strike issues with his hammer springs before (and I believe him), and the offending spring was dispatched to him for material and tension analysis. I'd like to give his springs a fair shake, and I accept that issues can occur despite the best of materials, processes and intentions, but it was still a massive fail regarding the hammer spring (the ISMI trigger return/triggerguard latch spring performed well, and is remaining in place). I'm awaiting his test results and a replacement, which I'm quite willing to test, as I've had excellent results with chrome silicon and shot peened springs in other platforms that have proven to be superb, and reliable performers.

Needless to say, I replaced the ISMI hammer spring with my Wolff 11# hammerspring. While the ISMI had provided a superior triggerpull, with less of a "hitch" or creep prevalent with Ruger and Wolff music wire mainsprings, it with my sample of 1 failed performance-wise; I'm hoping the replacement provides the best of both worlds (triggerpull smoothness and 100% reliability). I apply Lucas Red "N" Tacky #2 grease to the hammer strut and the coil spring interior of the Wolff, and that really seemed to interestingly smooth things out triggerpull-wise, and throughout the match I had 100% primer ignition reliability, using Herter, Federal and PMC 158 gr .357 magnum.

While with my Security Six I've come to prefer HKS speedloaders, with the GP I much prefer Safariland Comp II and Comp III speedloaders. They work well with the GP's cylinder and compact grip configuration for eventless reloads. The Comp III speedloaders are carried in a re-purposed Tactical Tailor AR15 double and single magazine pouches; the Comp II and HKS speedloaders are carried in a Bianchi ballistic cloth double pouch, with velcro flap closures and HKS's polymer double speedloader pouch, with gripper flaps; all of these pouches work well.

There is a significant difference in using full-house .357 158 gr cartridges compared to 125 gr or 158 gr .38 Special +P cartridges. .357 magnum really mandates both dry-and live-fire to successfully developing the necessary techniques with the magnum cartridges. Normally, I shoot and carry my Security Six with 125 gr .38 Special +P cartridges, and the GP100 with 145 or 158 gr .357 magnum cartridges, they respectively marry well with the platform characteristics of both of my individual revolvers, at least for me.

The match went well-I had a great time working on technique, accuracy and speed. One potential caveat regarding the Ruger/Altamont Compact Grip that I'd previously read about, but hadn't experienced; with use and accumulated GSR residue, the rubber grips can induce a blister on my strong-hand (right, in my case) inner thumb towards the base of the thumb, where it came under constant recoil force and torquing force; after some 100+ rounds, I had a raw and bleeding blister requiring bandaging (but I was not operationally hindered by it). I really like the Compact grip's comfort, recoil absorbtion and ease of carry, but I may experiment with one of VZ's new GP100 G10 grips in the future, and see how they perform ergonomically and comfortably (and avoid hot-spot blistering, etc).

Other observations: As roundcount accumulated, concurrantly so did chamber GSR accumulate , occasionally necessitating thumbing down roloaded cartridges for full seating in the cylinder; the Safariland Comp III reloaders are a big help, but I still needed to thumb-seat cartridges in the cylinder occasionally after reloading.

Apres-match, while cleaning and lubricating the GP100, I noticed some slight binding in the cylinder (while fully operational, it didn't seem to spin quite as freely as before), so I field-stripped the GP, and partially disassembled the cylinder (and appreciated the ingeniousness inherent to the GP100's design and manufacture in the process). While partial cylinder disassembly isn't inherently difficult, having some good disassembly/reassembly direction and diagrams and YouTube episodes is a huge plus, and really facilitated the process of both disassembly and reassembly. Having appropriately-sized punches on hand is also key. Partial cylinder disassembly, which removes the cylinder from the crane and ejector rod enables you to get in and remove the accumulated grunge, GSR and dried or paste sludge from the crane tube and inner cylinder, and the ball bearing race inside the cylinder tunnel. While many never feel the need to perform such, I find that periodically it's a good thing to perform, and decreased the cylinder friction on the crane, as well as making the cylinder closing and lock-up a bit crisper. Other than the punches for disassembly, Q-Tips, cotton patches and a quality light gun oil (I used Lucas Extreme gun lubricant) is all that you really need to perform this maintenance.

As my GP100 has a custom blue finish, to protect the finish I use a light coating of Rennaissance Wax for the exterior metal, and a light film of the Lucas oil elsewhere.

The holster I used in the match is Galco's new Switchback, which allows for OWB straight drop, slight backwards cant, or cross-draw carry. The cross-draw carry is a nice option for vehicle, horseback or seated carry. There is an optional retention strap provided, which is nice for carry when vigorous movements are anticipated. The Switchback is a great value for about $50, and provides both good protection and access; Galco makes several options to fit various revolver platforms; the one I have fits both the GP100 and Security Six, and I have another for my Blackhawk. While they don't have the exquisite feel and appearance of well executed custom leather, they do work quite well for use as a general-purpose holster.

Best, Jon

[Bruce Cartwright]

Jon:

Great write up with plenty of details. Thanks for doing this. Your report about cleaning your GP100 mirrors my own experience. I routinely keep a GI bristle brush in my range bag and brush/scrub the front of he cylinder, the forcing cone, the rear of the cylinder, the standing breech and underside of the ejector star. I do this at least once per range session. I find that keeps things running much more smoothly.

While I love my S&Ws, my go to pick for revolver work are Ruger Match Champions and Security Six series guns.

Bruce

[JonInWA]

VZ Grips and I had a great discussion this morning, and a set of their VZ320 and Twister G10 grips for the GP100 will be enroute to me to test. I'm looking forward to comparing them to the Ruger/Altamont Compacts in terms of index, fit, ergonomics and comfort.

Best, Jon

[JonInWA]

A quick follow-up: First, the two VZ grips arrived, and I'll be discussing them in detail after my upcoming match this weekend (I'll be running the VZ Twister grip, and may concurrently test the VZ 320 grip if time and circumstances permit); if not, I'll test the VZ 320 seperately, likely at a subsequent match.

Second, Marc Cosat of ISMI has received and thoroughly tested the ISMI chrome silicon hammer spring that I found to be so problematic; and his testing found the spring to be thoroughly within acceptable parameters. His thought is there might be something on the hammer strut inducing drag inhibiting the spring performance, but that doesn't seem to explain why I'm successfully able to run an 11# Wolff hammer spring with 100% reliability, so our game plan is after this weekend's match to send him the Wolff for comparative testing, as well as some images and measurments of my hammer strut. The goal will be to attempt to determine if the issues I encountered were spring-induced or if there's an issue within my GP100 elsewhere as a causal factor. The attraction of the ISMI chrome silicon spring is that there's inherently less stacking, and the energy release is different, which should lead to a smoother. lighter triggerpull. It'll be interesting to see where this goes; I'd certainly like to be able to take advantage of the ISMI's charactistics.

Ruger has graciously sent me a current OEM hammer and trigger return spring set, so I'll install at least the Ruger hammerspring while Marc is comparatively testing my 11# Wolff; the original Ruger hammerspring weight was 14#, but rumor has it that Ruger quietly lowered it to 12#; I'm awaiting confirmation from a source in Ruger checking into that for me, and it'll be interesting to run the GP100 with a current OEM spring as well.

Best, Jon

[jh9]

the upshot is that he's never encountered light strike issues with his hammer springs before

Nobody does until they do.

edit: Not saying that's specific to ISMI; it's a spring issue in general. I've found I can pretty consistently induce spring related primer failures by simply standing the same zip code as someone who's said "yeah, these light springs are 100% reliable" regardless of who made the spring.

[JonInWA]

What's a bit surprising is that Marc tested my spring with 5 other brand-new Ruger GP100 ISMI springs, and all were within acceptable performance parameters. Now, out of the 6, mine is probably the only one that's actually been used, so the comparison between my ISMI, the other ISMIs, and the 11# Wolff that I'm using (successfully) will be exceedingly interestingly.

The conversations with Marc have been very straightfoward and professional. We're both interested in finding out what's going on.

Previously, through empirical experience, I'd worked my Wolff hammer spring from a 10# to the 11#, using primarily Remington/Remington UMC and Sellier & Bellot cartridges. While I had several failures to fire per 100 rounds with the 10#, the 11# has been exemplery over the past several years.

Best, Jon

[Jim Watson]

Other observations: As roundcount accumulated, concurrantly so did chamber GSR accumulate , occasionally necessitating thumbing down roloaded cartridges for full seating in the cylinder; the Safariland Comp III reloaders are a big help, but I still needed to thumb-seat cartridges in the cylinder occasionally after reloading.

Which is why I carry a chamber brush in my revolver bag and dry brush at least every other stage, preferably every stage if there is a safety zone handy. And a toothbrush to clean out from under the extractor.

The only ISMI springs I have used were flatwire recoil springs in other than Glock ratings, which are fine; and 2011 magazine springs which were a dead loss.

[03RN]

Which is why I carry a chamber brush in my revolver bag and dry brush at least every other stage, preferably every stage if there is a safety zone handy. And a toothbrush to clean out from under the extractor.

The only ISMI springs I have used were flatwire recoil springs in other than Glock ratings, which are fine; and 2011 magazine springs which were a dead loss.

I found that between the snug chambers in my M19 and my grimy reloads that I constantly had to press my reloads home. Not all of them but 1-2 each reload.

Even with freshly brushed chambers Thats annoying.

It definitely had me contemplating moon clips or different speed loaders.

[Dave T]

03,

Just for practice and maybe competition plated bullets might be an answer. They shoot a lot cleaner than cast, at least in my revolvers.

YMMV,
Dave

[03RN]

03,

Just for practice and maybe competition plated bullets might be an answer. They shoot a lot cleaner than cast, at least in my revolvers.

YMMV,
Dave

That last match was with plated bullets. I had a bunch of 125gr @ 1350 loaded up but it was more the grimy cases (I need to start cleaning my brass).