Old3GNR

I'd also recommend loading the .223. A powder I've found to measure pretty well is Benchmark. I lube the cases with One Shot the same as I lube pistol cases. Hornady 55 FMJ, 25.5 Benchmark, WSR primer, 2.20" OAL. Rifle cases will grow in length after a few uses and will need to be checked and trimmed. I you start loading a lot, I highly recommend the Giraud trimmer.

My PCC load is almost the same as the OP but I went to a lighter buffer spring and changed one of the tungsten weights to steel in my JP. My velocities have dropped a little and I'm guessing its because the bolt is opening a little earlier. I can't outrun the gun and am getting minimal dot bounce.

I've hit and KD'd steel @ 350 with 52 gr. Sierras but I had a 1.75-6.0 scope. A 69 SMK will work but hitting with the red-dot will be a problem.

Here's an LSI 3-D printed part on a JP GMR-13.

To remove the mag release use a roll pin punch, I think it is 3/32, and tap pin out the bottom. There's another thread on this in this forum.

JP GMR-13. 5000 rounds, several USPSA matches, some Steel Challenge and a few outlaw K-D Steel matches. 0 malfunctions using a variety of handloads.

I'm running 3 Glock 17 rd mags with Dawson base pads and two Glock 33 rd mags with the TF extension. All have been 100% reliable in my GMR-13. Gun now has 5000 rounds through these mags.

I also like the 25 yard zero. The bullet is still rising at point of impact at 25, continues to rise then starts falling and is near zero again @ 50 yards. Per earlier post, hold at top of head for close head shot.

Nemesis, I've had no issue since installing the Odin part. I'm using Glock mags.

OP, The GMR-13 mag release is relatively easy to fix using an Odin Works mag release extension.

+1, I ran the +5/6 Dawsons on my 31 round mags with no issue. Bought TF 41 round extensions which worked well, had to smooth one at the junction. Moved the Dawsons to my 17 round mags, with 20 rounds I can easily reload on a closed bolt.

My last match this year was a USPSA "Monster Match". All classes shot the same stages. I used my TF 41 round mag and reloaded on several stages. The last stage was 60 rounds. With the MBX 57 round mag, this would have been the only stage requiring a reload. I was thinking about the MBX mag extension but now I'm not sure. Reloading while moving between shooting positions does not cost time. Screwing up the reload does. The advantage to a big mag is one less possibility of a screw-up.

Right on 125 with both guns. I haven't had an issue with steel falling but in my experience, there is a lot of variation in how steel is set. A few years ago I hammered a popper 2 or 3 times with a 145 PF 165 gr .40 and it didn't fall. My squad mates urged me to get a calibration done. The match director shot it with his 9mm and it fell.

There's a lot of factors and you'll really need to try various loads and chrony them. When I initially tried my pistol load in my JP PCC, It ran 108 pfs faster from the JP. I have since lightened the spring and buffer in the JP and my last loads run about the same in either gun. I've tried 115, 124, and 147 JHP (running JHP to minimize lead in the comp). I've settled on 3.5 Tite Group with the 124 bullet.

With my GMR-13, 17 rd mags loaded with 15 rds load fine on a closed bolt. The same mags with Dawson +5 base pads work even better with 20 rds. Usually start with TF 41 rd mags fully loaded with an open bolt, with 40, they load with a closed bolt.

JP trigger which is now about 2#.

Just a data point. My JP GMR-13 now has about 5000 rounds through it and after reading about these failures, I pulled out the FP and it looks new.

My JP GMR-13 has run 5000 rounds of my assorted reloads with no malfunctions. It did need an extended mag release and aftermarket mag well. Handguard is a little heavy but I don't thinks it slows me up and would be easy to change.

L9x25 and others, Interesting observations. I'm trying a new 124 JHP load for my JP. , 3.5 gr Titegroup ran 993 fps or 123 pf. I ran the same load from the same batch at the same time through my HK VP9 and got 1008 fps and 125 pf. Here's the interesting part. I previously ran a 124 FMJRN with the same charge through the JP and it ran 1086 fps with 135 pf. Since I chronoed that load I had replaced one of the tungsten buffer weights with steel and dropped to the light recoil spring. For reference, the 124 JHP ran 940 with 3.2 gr Titegroup and 964 with 3.4 gr.

In my Remington 700 LTR, 175 SMK over 44.5 Varget w. CCI BR-2 primers has been a great load.

A 57 round MBX would have gotten you through 7 of 8 stages at the Ontelaunee Monster match. My issues were lack of memory!

My last "Major" match pistol win was High Super Senior at the Mid-Atlantic Sectional in 2004. I dropped out of USPSA in 2010 but continued shooting Tac Optics 3-Gun. Lately I've really struggled with iron sights on my pistol and did not shoot any 3-Gun this year. Bought a PCC, added a dot and am back having fun in USPSA. Add CO to 3-Gun and I would be back.

I had an older 41 and used it for shooting .22 9 Pin and other speed games. 100% reliable with CCI Mini-mags. Wish I never sold it.

My JP GMR has been 100% reliable for its first 4400 rounds. Its heavier than some and has little recoil. I shoot reloads but some are the same as factory.

I just entered a "Monster" match, 350-400 rounds over 8 stages. I have two 41 round mags but they will not reload on a closed bolt. My JP GMR-13 doesn't lock back when empty. I'm thinking of starting with the 41 round mag and reloading at a point before it runs dry with a 17 round mag to finish. Any good ideas?.