Galun

with sport pistol it can, each click in the powder drop bar is about 0.05. You may very well be right on the pcc barrel more friction. I was used to rifle longer barrel = higher velocity. But at pcc velocity maybe friction has more impact.

i think he is talking about the Jp scs replacement spring. The manual states that the stock scs has the 85% spring, and it’s indeed the clear / black spring. https://www.jprifles.com/buy.php?item=JPSCS-PACK15

Went to the range today and tried a few loads I had left from prior load development for my gmr-15 (glad I saved those rounds during all these years!). Hope this helps someone. 3.5gn sport pistol / 147gn Xtreme CPRN / 1.15 OAL => 910 fps ES 56 SD 16 PF 133 3.4gn sport pistol / 147gn Xtreme CPRN / 1.15 OAL => 870 fps ES 65 SD 20 PF 128 4.98gn sport pistol / 124gn PD JHP / 1.15 OAL => 1259 fps ES 44 SD 18 PF 156 4.79gn sport pistol / 124gn PD JHP / 1.15 OAL => 1244 fps ES 30 SD 13 PF 154 5.9gn long shot / 100gn Xtreme CPRN / 1.15 OAL => 1390 fps ES 38 SD 18 PF 139 3.76gn long shot / 147gn Xtreme CPRN / 1.15 OAL => 852 fps ES 65 SD 27 PF 125 4.08gn power pistol / 147gn Xtreme CPRN / 1.15 OAL => 896 fps ES 57 SD 23 PF 131 I didn’t like the recoil feel of power pistol. There was no perceptible difference between long shot and sport pistol. I am probably going to stick with 3.4gn sport pistol which is my carry optics load. It actually makes a higher power factor in my P320, 131PF. Maybe I split the difference and do 3.45gn and only have one load for carry ops and pcc. Normally the 16” barrel should lead to higher velocity, but I suspect the 147gn Xtreme being 0.356” diameter leads to more friction. It behaved the same way in my GMR-15, the same ammo makes a lower power factor in the pcc compared to the pistol. My precision delta 124gn (0.355” diameter) behave more normal, higher power factor in pcc than pistol.

I would probably leave the 70 in it and be done with it. But note that my experience is still limited. I shot my friend’s gun and I just got mine. looking at the brass ejection pattern of the 60 in shooting my 131pf ammo, i would not trust it to be reliable over an entire match. It worked for both of us in one stage but the brass ejection was very close, some seem to be almost like falling out. wasn’t really focused on recoil, it’s already very soft. Was more focused on dot movement and there was very little. the chrono was almost spot on compared to my gmr-15. I am going to load up some rounds with long shot and see how it feels compared to sport pistol. Recipe is 4.2 grains 147gn 1.15 oal for around 130pf out of a gmr-15.

We didn’t use the 80 during the match but it would have been even more reliable since the 70 worked with low power factor ammo the entire match. I personally didn’t try 60 vs 80 during this match, I only shot the stage for fun after the match with the 60 and 131pf ammo. Will have more feedback after the next match in 1.5 weeks. Overall between the match and the practice afterwards I’d say we did 3-400 rounds with over 100 rounds with the 60 degree locking piece with 131pf ammo, and not a single failure.

Shot a match recently with a friend. 3.5gn sport pistol, 147gn Xtreme CPRN, 1.15 OAL => 131 PF. 70 degree locking piece ran flawlessly entire match. After the match we ran one of the stages twice with the 60 degree locking piece and it was fine, but brass ejection was a little weak and sketchy. Has anyone tried a slower powder like long shot? (They called it far shot in the 2017 pcc load development article, so I assume that’s a potential powder choice). For people with better technical knowledge, what would a slower powder do to this mechanism? In the gmr-15 the slower powder would theoretically produce more has to work the comp I think.

I tested a bunch of loads today using recipes suggested by others here. 4.8gr sport pistol (proxy to n320) is indeed low 130s PF out of a 5 inch barrel (shrouded to 16 inches). with the ultralight barrel I seem to get better groups (measured by bill drill) with low PF. I got the best group with 147gr using 3.6gr sport pistol making low 130pf.

Hi, can you share the recipe for the 115 gr? What powder and charge got you to 133 - 135PF? I got tuned ammo 147gr 130PF for the 14.5” pin and weld and there was minimal dot bounce. Switched to the ultra lite and there was a lot of dot bounce. Would love to try some 115gr loads. Thank you.

Thanks for this - makes sense. I had a good load at 147gr 3.5gr sport pistol pushing 890fps with a jp 14.5 inch barrel with the new vertical comp, and dot bounce was minimal. Then I switched to the ultralight barrel and dot bounce was quite bad. If the prvi load works for you then I will try to load some 147gr for almost 1000 FPS and see how it goes. Thanks!

Would you mind sharing your recipe for 147gr? Are you using 5.5” and 16” barrels? I am trying to tune out my dot bounce for 147gr but I only got it to 900 FPS for low 130s PF. Maybe that’s the problem, too low of a PF. Thank you.

I think shroud barrel and side charger will be available later. Gotta see the market reception of a $3350 pcc. If it is a meaningful improvement and people are willing to pay for it, then they introduce the $400 barrel add on and $600 side charger upgrade. If the launch fall flat then they wouldn't have spent money developing those options. It’s prudent market testing.

Surprised to see nobody talking about this yet. Preorder is available and pricing is out. $3269 for the competition version with their tube handguard and pcc compensator. $3349 for the steel challenge version with their mlok handguard and titanium compensator. Looks like net weight savings of around 7oz (0.4lbs). I had been told that the roller delay mechanism makes this shoot like a 22 with very little recoil, and thus the compensator really isn’t necessary. Even if I shoot USPSA, I should go for the steel challenge version due to the weight savings. https://jprifles.com/1.2.18_JP-5.php?menu_select=rif_buy_menu

Mine is 45 degrees but it doesn’t go out sideways far enough then bend 45 degrees, so it’s a little to the left of the barrel after I have a cheek weld. you just reminded me that jp makes one. I will order from them. Thanks!

Hi, I recently tried an offset mount and I like it. However the mount I have does not have the correct height over bore. Can anyone recommend one that works well with the jp gmr-15? Thanks! Thanks!

I just developed a load that I really liked out of my gmr-15 with 14.5 inch barrel and pinned new style compensator (the one with port on top). 5.9 grains of long shot, Hornady 0.355 100gr FMJ, 1.08 OAL. Makes around 140-145 PF. Great snappy feel, dot bounced back quickly and felt like it barely moved, flat and accurate.