GregJ

Copy that, thanks. I mean to type copper streaks, instead of carbon streaks. But I assume the same holds true.

I do a deep clean (scrubbing, brush, etc) on the barrel generally about every 500 or so rounds. Between I may just run a bore snake though a few times. How do y'all address the carbon streaks left in the chamber? Leave them? Scrub them out? Just dont want them to build up causing issues. TIA

In my somewhat limited testing so far, to me, tuning the JP-5 is very similar to tuning an AR with an adj gas block. Proper brass ejection is critical to optimum performance. You might be able to get it to shoot really soft, but will it be at the cost of optimum reliability? JP has recommended in their vids that brass should land about 3 yds away for optimal performance. For my loads that are running 135-140PF (mostly 147 Blue Bullets), the stock 80* works best. I have tried the 70*, but brass would dribble out and land about 1-2 ft away, and an occasional FTEject. With lower PF loads (120-125PF 115 for SC), the 80* would work, but had an occasional FTEject. Softer loads seemed to eject brass better with the 90*. Recoil will never be as soft as my MPX, but that is ok, the JP-5 excels in so many other areas. It is not that much more to be so noticeable anyway. As an FYI, JP also recommended adjusting first with different Timing Pieces, then weights (swapping steel for tungsten on the SCS). They suggested not changing the spring, as their testing has proven the stock black spring has performed the best. I know others have done a lot of testing/changing with springs. To me it made little difference in how soft it shoots, but big difference in brass ejection and reliability. YMMV

Anyone have the optimum OAL for the JP5? I know my MPX's are pretty picky, 1.120 - 1.140 I thought I read 1.100 to 1.130 somewhere, but cannot find it.

When you tested these loads, was it with stock block/spring/weights? Or did you change anything? My current load is 147 Blue with 3.6gr Clean Shot, 138PF. The stock block/spring/weight combo (80*, black, 2 steel) seems to work great with this load. But I have a lot of 115 and 124gr pistol loads already loaded (for CZ S2) that I want to test with next. They are around 1.100 (CZ has short throat), so I hope they will load fine in the JP5. I have watched every JP video on the 5, and it seems that JP recommends: - Tune with the block first, then the SCS weights. - Brass should land about 3 yds away. - Shouldn't need to change the SCS spring, as it has been "optimized" for this system. But can change to fine tune if desired. Playing around with different blocks (70, 80,90 with 147 load, 138 PF), I can tell if one is slightly harsher than the other, but barely. To me, the biggest indicator of the "correct" block is much like adjusting an AR gas block, how far away the brass lands. If it it lands 1-2 ft away, it may shoot "soft", but probably wont be reliable. Playing around with SC load (115gr Xtreme, 123PF) With the 80 block, brass was landing 2-3' away and did have 1 FTEject. 70 block brass was 1-2' away, basically dribbling out, 90 block brass was 3-5' away. Need to test other blocks. The second biggest indicator for me is shooting fast doubles at 4-5 yd, and not watching dot specifically (match speed). If both rounds are landing in same hole, then the block is probably right. Using different blocks I have seen a distinct difference in round placement (first round all in one hole, 2nd round all in 2nd hole 1" low, or shotgun like pattern).

I tried a Blade, didnt care for it. DM me if you would like it. I’ve tried Holosuns, Eotech, Aimpoint t1 and t2, Trij MRO HD, and a Blade prism. Put a DPP on the new JP5. So far with my old eyes eith astig, it seems to flare the least. Plus it is low so mechanical offset is about as low as you can get. Plus there is minimal material around the optic making it easier to pick up targets. YMMV.

RHT. They are also great supporters of the sport. Use my code greg10 to save 10%.

Nope. Might have been some small scratch somewhere I couldnt see. Or something else. I borescoped the barrel and there is a small nick at the crown. Maybe thats it? Doesnt seem to effect accuracy though

@GrumpyNO yeah, ordered those before reading this post completely. Will order a 70 tonight. Tks @OldRunner Condor. Had it for several years. little faded, but has held up well https://condoroutdoor.com/collections/gun-bags-weapon-cases/products/condor-36-single-rifle-case

Joined the bandwagon. Picked it up sat, put 30 rounds in it to zero, then shot a SC match the next day to begin getting the feel of it. Gun ran great, no issues. 2gun match with it next sat, then MD State match the following sat. I had my last straw with my MPX (turns out after only 12K rounds the bolt was cracked all the way around), so I pulled the trigger on the JP5. Went through the builder, put my order in, etc. Called Ben when my build was processed. He said they had a 14-16 wk build time, and he looked around and found one for me at Arnzen Arms. JP had shipped out 15 blems to various dealers. So I was able to get one in a week and not 16, and saved around $500 plus no tax or shipping!! JP and Arnzen were great to work with. With just over 200 rounds through it so far, I think it shoots almost as soft as an MPX (Gen 2 or PCC), but does seem to have a little more push to the shoulder. Need more range time to get a better handle on dot bounce, or lack of. The trigger is amazing for a stocker. 3# 11oz, and zero take up, it just breaks. Very nice. Used to Hyperfire Gold on my MPX PCC. I think the stock trigger will be just fine for me. Shooting the same loads as I had my MPX with no issues, 147gr Blue Bullets with 3.6gr Clean Shot. In the MPX this load is about 142pf, but the JP5 is 135-140pf. Interesting. I have a butt load of Blues, so will be shooting them for some time. Not worried about comp build up, will clean it as it needs. I have a 90* and 100* block on order, to see if and how they affect recoil. Right now, with this load, and the stock *80 block, brass is landing a little more than 6' away.

Not shot the JP5, but have 2 MPXs, about 60K rounds between the two, Gen2 and PCC model. My biggest issue with the MPX is Sig and their parts availability. Your other alternative is ILWT, but now you only have one source for all your critical parts. My next PCC will be a JP5.

Will do that at next replacement. No real extraction issues as of late. When I did have an occasional one, I thought it was due to a weak powder change not generating enough gas, short stroking the bolt . When I started out with the MPX (both Gen2 and PCC), several issues, narrowed down cause to powder/gas related. All seemed to go away after opening the gas port. Now running Clean Shot in both with no issues.

MPX PCC model (Gen3), with about 11K rounds, shooting normal USPSA handloads (135-140PF), gas port opened .0625. Broke 2 OEM extractors in last 3 months. I had been running the BCM extra power AR extractor springs, and I believe the extra spring height, plus the donut, and insert, combine for a compressed mass that is more than the MIM extractor can handle, and eventually fatigues at the pivot point. I have over 30K on my Gen2 MPX, and never broke an extractor, but I dont think I ever ran the BCM springs in it. The BCM spring is on. the left, center is the red extra power (stock with Gen3?) , and on the right is the OEM spring. The BCM and red spring both are 4 coils, the OEM is 3.5 coils. I think I went with the BCM spring to address some issues, but will be going back to the red extra power spring with donut and insert. Which spring are you running? And with or without the donut?

I know this topic is fairly old, but thought it might help someone. I have 4 sets of gas plugs/tappets that I rotate each time I clean my MPX, which is about 3-500 rounds, I try not to go longer than 500. If I have to really wrench on the plug to move it, then it's gone too many rounds. The dirty plug and tappet go into a small container of CLR, where it will stay for at least a week. I dont care about the finish on these parts. By then any carbon can be wiped off with a rag or an old tooth brush. I will spray Gun Blaster or equivalent on the rings and blow clean with air hose. Yearly I will replace all rings on plug and tappet, scrape the grooves clean (usually minimal gunk is in the groove), the expansion hole, inspect, etc. At each cleaning I have a .45 bore brush with copper strands from a chore scrubber wrapped around it, in a pistol rod and chucked in a drill, use a cleaner like Hoppes or maybe Iosso on the brush to clean out the gas chamber. Clean chamber, lugs, run bore snake through several times. Yearly I will do a deep clean on the barrel and get it back to bare steel. Clean/inspect bolt and extractor, replace spring about 2K, depending on how it and donut look. Spray Gun blaster in trigger, blow out with air hose, lube with Mobil 1 oil. I have a mix of grease and Mobil 1 that has consistency of syrup, that I use liberally on BCG. I've tried the sonic cleaner, too messy for me. YMMV.

Just put a Hiperfire PDI Black in my MPX PCC. Stock Timney was 5.5#, PDI about 2.5#. Sweet trigger. Also have an early Competition (formerly 24C) in a GenII. Great triggers.