PaleoMan

Ah, that link you gave was useful. I watched some of the videos and one showed that the disk is sometimes used as a shim. I checked, and my SCS was almost flush, and with the disk as a shim, it now sticks out the recommended quarter's width.

I’m still kinda confused. Is it something that is part of the assembly, or is it something that sits in the lower? The SCS has a screw on the end, which is tightly attached, and there’s no way this goes over shaft of the SCS. Any pointers here?

I have a new JP-5, with just a few thousand rounds through it, that I've cleaned a few times so far. Today, I took out the SCS (for the second time ever) to look at it and wipe it off and this metal disk (shown to the left of the SCS) fell onto the floor... Any idea what this is? My guess is that it might have been on the back end of the SCS. It is the same size as the center circle on the back. Was this something from manufacturing, left in, or is it some spacer that should be in there? I put it in the end of the buffer tube, behind the SCS. Was just curious. Reminded me of those stories where someone takes something apart and then puts it back together and has parts left over.

Interesting. Do you know what lock they used?

I usually stick to well known or popular cases (e.g. R-P, Federal, Blazer, Sig,...) and sort them into containers. I have one container for lesser known brands or ones that I just don't see a lot of (e.g. Aguila, Hornady,...). Then, I have one container for everything else (some no-names and some military head stamps). Those will end up going back to the range - they collect brass and use it to fund shooting programs for kids. I load up the case feeder with one container, and if it runs out, I transition to another container, and start marking the heads with a different permanent marker. I just had a brain fart and accidentally poured some of the junk ones into the hopper - wrong container. I spent quite a while separating the cases back out. Argh! I'm still curious as to why I get some larger spreads and std. dev. I'm not sure if it is my technique, primers, bullet selection, powder, OAL, crimp,... I think the OAL is fine (1.125" for the JP-5 use, of which I could go up to ~1.132" from checking the seating). The crimp is close to the SAAMI spec. A friend of mine has a 750 and we were thinking of having him load with my powder and bullets to see there is a difference in technique. He also has Berry bullets and we were going to try those vs my coated bullets. Fortunately, he's anal an engineer, like me, so we have fun researching into this.

Good catch! I sort my cases by headstamp and then make batches. Well, I ran out of R-P cases, and switched to Federal just before this chrono-ing and testing. Unfortunately, I have a container of miscellaneous cases (which are only used when setting up my press as depriming cases or as OAL/crimp measuring cases), that got accidentally loaded into the case hopper of my Dillon 650, along with the Federals. Argh! I was able to separate out enough of the Federal only cases for chrono-ing, but for doing the eject testing there were other cases mixed in. I guess that is likely the cause - though I'm surprised of the effect being that pronounced. I have been wondering about my amount of crimp. I've taken some factory ammo and measured the crimp the best I could, and then set my crimp to the same (it's hard to measure). The federal cases appear to be about 0.375" at the crimp location. My reloads are about 0.379". Anyone have thoughts on that? I've heard folks mention about crimp affecting consistency, though I think they were talking about too much of a crimp.

I made some low powder, ~120 PF, loads. They were soft shooting with the 80 degree lock, seemed to group well, but the ejection was somewhat erratic. Some cases going straight out and landing about 4-5', but some only dribbling out and landing only about 3'. There were no malfunctions or issues, but I think still with the higher 140-150 PF loads I made. I've got a ton of the coated 125gr bullets, so I'll use what I have. In the future, I'll probably try different weight bullets.

You'll love it! A fabulous rifle. I think JP suggests looking for an ejection of cases of about 2-3 yards. When yours comes in, you can try the lock you have (probably an 80) and see how it works with the loads. Mine came with the 80 degree lock and I bought the 70 degree lock. I'll likely buy (or better still try to borrow) a 60 degree lock to see how it works with my 140-150 PF loads.

With the (factory) Syntech ammo, I was seeing about 150 PF. With CFE Pistol powder, and after I adjusted my OAL to 1.125 so that I complied with what TF mag extensions recommended, I was seeing 140-153 PF, when running from min to max load. Those same loads on my Walther Q5 gave 129-138 FP. With HP-38, running from min to max load, I was seeing 140-152 PF (132-141 PF on Q5). So, I could get a good load for USPSA/IDPA on my Walther Q5, but the JP-5 was much higher (expected). I was finding that with the 70 degree lock, the cases were still going 6-10 feet. With the 80 degree lock, the cases were really going far. When, I tried load below the min, I was still getting PF in the range 119-135 PF with CFE and 117-127 PF with HP-38. With those, the 80 degree lock seemed to throw brass pretty well, about 6-9 feet, and the shooting was very soft, with the really low loads. In general, the HP-38, a faster powder than the CFE pistol powder, gave lower std. dev and spreads (4.4gr gave std dev 6.94, spread 18.24 fps). With the bunny fart loads, the spread and std. dev. was high 20-30 range, but they shot fairly tight groups), even though the POI was different (I need to check, because I think it was about 1" lower than POA at 20 yards). I'm forming the opinion that, if I want to shoot with a PF in the 140-150 range, I'll use the 70 degree lock (I don't have a 60 degree lock), and if I want to shoot with 120-130 PF range, I'll use the 80 degree lock. Since I'm initially using the JP-5 for Steel Challenge, I'm seriously considering to test in larger quantities, the lower PF load to see how reliable it works, as the recoil was very soft. I can make a higher load that, with the Q5, will be in the 130-135 PF range. If I have to use those loads with the JP-5, I'll use the 70 degree lock, as they will be pretty high PF. I have to admit, after only shooting a .22 rifle for SC, and this being the first PCC shot, at the load I was running, I do have to focus more on managing the recoil. It was by no means as bad as other PCCs from friends that I toyed with briefly. Oh, and lastly, a friend of mine has a (stock) competition MPX, which he brought to the range and I shot a few strings of 5-To-Go that I had set up, and then immediately did the same with my JP-5. Subjectively, both of us felt that the JP-5 was a little lighter, and I really felt that the balance of the JP-5 was MUCH better than the MPX. It made me feel good about my decision to get the JP-5.

Yeah, I reported in a different thread on reloading... I think one issue I had was that the OAL was quite short (1.157" IIRC), and folks were thinking that the bullet was jumping to the lands and being inconsistent. I did drop checks on the JP-5 and realized that the OAL could be up to ~1.132", so I made some rounds at that OAL. The std deviation was MUCH better. Of course, I then realized the comment someone had made about the TF mag extensions won't work well with OAL > 1.125", so I changed the OAL again. I also found some HP-38 powder (just a pound), in addition to the ton of CFE Pistol Powder I have. With my 125gr coated bullets, I found these results... With CFE Pistol Powder, I got the best std. dev. and spread with 4.8gr of powder. Getting about 143 PF. Seemed to work well with 70 degree lock and recoil seems OK (better than if I use Syntech 124 gr cartridges). I got reasonable stats for a 4.0gr load (119 PF) and it shot very soft (4.2gr worked well too), using a 80 degree lock. With HP-38, 4.4gr @ 152 PF worked well, and a 3.6gr load shot very soft (127 PF). In general, I seemed to get better numbers with the HP-38 (a faster powder). In all cases, using 70 degree locks for the higher PF and 80 degree lock with lower PF, there never were any issues with feeding/ejecting of rounds. Ran flawless with easily 1000 rounds of testing and I even tried it at a Steel Challenge match. On my Walther Q5, which also worked well with these rounds, I found that the stats were better with a hotter load, but manageable. I'll likely use the loads best for JP-5, as they were pretty good on the Q5 too. I don't want to build multiple loads, for each gun, if I can help it. I'll likely settle on the 4.8gr CFE pistol powder. I do want to find some faster powders to try (Tightgroup, AA2,...) just to see how things work out, as a future powder to try. I also may try the low PF in a match to see how it works out. In the future, I may want to try different bullet weights, but I've got quite a few of the 125gr Precision Bullets left. It's been fun playing.

@Darqusoull13 Thanks. I did spend several hours last Saturday, shooting a Steel Challenge Pendulum setup with friends. It was lots of fun (and great to meet up with folks I hadn't seen for a while and play with everyone's toys). I'm really enjoying the JP-5. When I first started, the loads that I had, were showing a large std dev on both Q5 and JP-5, and that is when I decided to tinker, lengthening the OAL and getting better std dev (and accuracy). I had revisited several threads in the forum about JP-5, and realized I didn't think about checking the mags, and about the mention of a shorter OAL. So, today, I just adjusted my OAL so that it is 1.125-1.127, and created a new ladder with powder to see how the std. dev and PF look with the new length. Goal Friday (weather permitting), is to see if the 1.125 and/or 1.133 rounds feed reliably from FULL mags with TF extension, which I have not checked. In addition, I'll check the PF and std dev of the 1.125 rounds, using the ladder I created to see what works best. With that ironed out, I want to then focus on how the recoil is with both reloads and Syntech. I had a mistake on the chrono data for the Syntech ammo above (it was for the Q5). For the JP-5 with Syntech, I get: Average v0 fps 1217 1202 High fps 1242 1231 Low fps 1196 1168 Spread fps 46.03 63.45 Std dev 14.92 26.37 PF 151 149 So reloads have been 130-145 with one powder, and 137-149 with another, and about 150 for Syntech.

Now that I have the JP-5 and have been playing with it using Syntech 124gr and my reloads, I have a few questions... With my reloads I have Precision Bullets coated round nose 125 gr bullets, CFE pistol powder, Wolf primers. Initially, I had a 1.115" OAL I had a Hellcat where it was not chambering with a longer OAL, so I lowered it. However, with this OAL, I was seeing a high spread and std dev on both the JP-5 and my Walther Q5 match SF. Here is tests, comparing with Syntech 124gr rounds. JP-5 PB 125gr 4.6 gr CFE Syntech 124gr Ave Vel. 931 1034 Max Vel. 949 1044 Min Vel. 870 1022 Spread. 78.75 24.54 Std Dev. 23.45 7.96 PF. 116 128 Walther Q5 PB 125gr 4.6gr CFE Syntech 124gr Ave Vel. 1012 1111 Max Vel. 1057 1139 Min Vel. 943 1089 Spread. 114.18 40.66 Std Dev. 34.71 12.39 PF. 126 138 As you can seem, much higher variance with the reloads (granted, different bullet shaped, primer, powder...). The accuracy was not as well as I expected. I posted in the reloading section, and there were two suggestions, one that the CFE pistol powder was a slower burning powder, and the other that the bullet may be jumping to the land and causing the deviation. I did some plunk tests and checking and realized that both the Q5 and JP-5 would accept up to about 1.132-1.133" before touching the lands. I created a ladder of loads with this OAL and got better results: JP-5 4.6gr 4.8gr 5.0gr Ave V0 1045 1107 1167 Max V0 1087 1128 1212 Min V0 1005 1078 1116 Spread 81.72 49.47 96.31 Std Dev 27.96 17.58 30.07 PF 130 138 145 I made more cartridges with the 4.8gr, as it had the better std dev. for the JP-5. Q5 4.6gr 4.8gr 5.0gr Ave V0 1007 1054 1098 Max V0 1051 1089 1118 Min V0 955 1028 1080 Spread 95.47 60.55 37.74 Std Dev 27.19 18.84 13.91 PF 126 131 137 I also had some HP-38 powder and did a ladder with that, giving these (even better) results: JP-5 JP-5 4.0gr 4.2gr 4.4gr Ave V0 1103 1154 1198 Max V0 1114 1180 1240 Min V0 1087 1124 1182 Spread 26.87 56.10 57.63 Std Dev 9.81 18.73 17.63 PF 137 144 149 Walther Q5 Re-reading this thread, I noticed the comment about the Goliath mags (I have two, but haven't used them yet) and using 1.125" OAL. Q1: Anyone have suggestions about how I balance, what seems to be better performance with the longer OAL and the need to lower the OAL for the mags? Granted, I didn't try higher loads, when I did the shorter 1.115" OAL, as I was looking for about 130 PF. Q2: With the Syntech (giving about 150 PF) and the CFE loads with 4.8gr and ~1.132" OAL, I see the cases going 8-10' with the 80 degree lock, and about 6-8' with the 70 degree lock. I recall hearing about the desire for 2-3 yards for case ejection. Should I explore a 60 degree lock? At what point should I be concerned about for ejection? 3 ' or less? So far, everything has been reliable, both reloads and Syntechs. I have about 400 rounds through the JP-5 (I finally cleaned it). I've been using several mags, only filled with 10-20 rounds though. I guess I need to try filling mags and seeing how things go. I need to shoot more with the different lock pieces to get a feel for the recoil. It's my first PCC, so I have no reference yet. I also haven't put any though yet into trying bunny fart loads for Steel Challenge use (something I've never done before- I usually keep it around 130 PF, as I was using the Walther Q5 for IDPA/USPSA). Any other suggestions by folks?

I usually chrono ten shots for each load in each firearm.

I realized I had. a pound of HP-38 laying around, that I bought a few years ago, but never tried. I chrono'ed them, using the same OAL, Precision Bullets, and R-P cases. Here are the CFE numbers for reference: With HP-38 I did 4.0, 4.2, 4.4 (the range for LRN was 3.8-4.4 in the Hodgdon databook), I got these numbers: Q5 4.0gr 4.2gr 4.4gr Ave Vo 1044 1080 1121 Max Vo 1070 1096 1130 Min V0 1029 1059 1130 Spread 41.42 37.66 18.61 Std Dev 12.88 10.35 6.07 PF 130 135 140 JP-5 4.0gr 4.2gr 4.4gr Ave V0 1103 1154 1198 Max V0 1114 1180 1240 Min V0 1087 1124 1182 Spread 26.87 56.10 57.63 Std Dev 9.81 18.73 17.63 PF 137 144 149 Note: The temps were about 48 degrees for this test, versus near 25 degrees for the CFE pistol powder tests. The standard deviation was better with the HP-38, than the CFE Pistol Powder (I should have re-chrono'ed some at the same time, with the higher temps). With the Walther Q5, it seems like the higher loads, as with each powders there was a lower standard deviation. With the JP-5 the CFE Pistol Powder had a better std dev in the middle load. With the HP-38, it was best on the low end, and increased quite a bit with the other two (are they the same, just within a margin of error?). Any comments on the data gathered? It "seems" like the PCC does best with about a 137-138 PF, given the 125 gr bullet and OAL I'm using now, and the Q5 when closer to 140 PF. I only need 125+ PF for the Q5, and usually want it to be around 130 PF to be safe for matches. I haven't explored trying an even lower load for JP-5 to see what the PF is and the std dev. Would it be expected to be a higher std dev?

Interesting info. Thanks! I'm hearing lots of good things about AA2, along with the "yeah, it's really hard to find". Locally, I could only find Ramshot Competition, Alliant American Select, and Hodgdon H-38.