CaliPCC

I just ordered a vltor charging handle, thinking just maybe that might be the culprit. It's a hail Mary at this point. Yes, on the last round the bolt catches on the follower, when I depress the follower the bolt closes. I really have no idea what is wrong.

Received the SI bolt, haven't shot it yet but hand cycling seems to be working. I am having two issues. I don't use LRBHO on my competition gun and it seems like the SI ramped barrel and bolt are only supposed to be used on guns that do. Issue #1: full magazine cannot be loaded on closed bolt. Issue #2: on Magpul magazines, the bolt catches on the follower after the last round is fired. Is this supposed to happen?

No visible damage, ramp is smooth to the touch

I fired two rounds, gun jammed when loading so it wasn't the root cause, I'll inspect the ramp to double check though

Changed only the barrel and handguard, I'm guessing the face of the barrel needs polish, or the magazine is not seated high enough.. I purchased an SI bolt to rule out if the issue is with the bolt. I'll see what SI responds with.

Received bolt after modifications and feeding issues are worse, will report back with what shooting innovations recommends

According to shooting innovations the QC10 bolt requires modification to work properly with their ramped barrel. They offered to modify my bolt. The lower part of the bolt has to be reduced by 50 thousandths. I've sent the bolt in for modification.

Having feeding issues with new SI ramped PCC barrel, wanted to see if anyone has any cures. Components: QC10 upper and lower receiver, Glock QC10 bolt ETS and Magpul Glock magazines Factory ammo (federal syntech) Issues - magazine won't feed in when full - ammo gets caught at an angle between the barrel and bolt Didn't have this issue with kvp barrel

No video as of yet @bwillis but a fine idea, I'll make sure to post after next range session- I should mention I'm having a two port Taccom comp installed, probably post something next week.

I have a QC10 receiver set, bolt and kaw valley 16" barrel with their linear comp build shooting factory 9mm. I've had issues with this build making it shoot flat, I've replaced the stock, buffer tube, went from Taccom 3 stage short stroke buffer to the Blitzkrieg HD with their SS spacer weight, tried 9 different buffer springs, tried a variety of ammo grains and manufacturers. Still, there is too much pressure on the internal parts causing the safety to come loose after 10 rounds and other parts in the lower. Dot still bounces up and I'm beginning to think that the barrel may be the issue. Another shooter on my squad has a NF lower and complete kaw valley upper using the kaw valley 7.5 oz buffer shooting Winchester white box 115gr and the experience is much smoother. Was thinking to go with either a 10.5 or 7.5 barrel length and weld the Taccom barrel extension with muzzle brake, hoping that it would be the cure all. Any feedback is greatly appreciated and please discuss optimal barrel length for 9mm.

I'm using different types of factory ammo, not chrono'd from 16" barrel- aguila 124, blazer 124, Speer 147, federal 124 & 147, Winche ster 115 & 124. Planning on trying some subsonic ammo. Used the Taccom spring the buffer came with, then tried the Taccom 308 carbine spring (not a good idea, magazine kept falling out), tried the JP 308 rifle spring (had to put the weight back in, shoots better, has slight muzzle rise but settles quickly, but now every screw on the rifle is shaking loose, hah) I think the 308 springs are probably too heavy so I ordered a normal JP rifle spring, sprinco blue and red to test.

Thanks for the feedback. I'm using the QC10 bolt with the weight out and with the Taccom buffer short stroked I still am getting a bit too much muzzle rise and dot movement than I would like using factory ammo. Experimenting with different buffer springs and ammo, I'll see if I can get the whole system to shoot flatter..

What buffer spring and bolt are you using? Thanks in advance, I'm trying to tune my system to the Taccom buffer.

I just built a PCC with QC10 receiver, Hiperfire Reflex trigger and Taccom short stroked 3 stage buffer with JP 308 rifle spring and experienced doubling and tripling at the range today. Recently added KNS pins to the hiperfire. Testing with Taccom supplied rifle spring proved reliable, however muzzle rise was not acceptable to me as this will be a competition gun I need it to shoot flatter. Testing with Taccom 308 carbine spring the gun shot flatter but shook enough to drop the magazine after every shot or two. I'm using different types of factory ammo, not chrono'd from 16" barrel- aguila 124, blazer 124, Speer 147, federal 124 & 147, Winchester 115 & 124. Planning on trying some subsonic ammo. Wondering if anyone has some feedback on what I can do to make it shoot flat and reliable. I'll order another spring Eric suggested, perhaps it will solve all my issues. Many thanks.

That's really sound advice. I'm a software engineer by trade, so I try to make one change at a time when troubleshooting. I will definitely follow your path. Thank you.

Thats good to hear, always good feedback from people with the same setup, I feel more confident going that route now.

Hard to say since it's so subjective and my experience is limited. The other carbines were at least a pound heavier, mine is at 6 pounds. Just want the groups to be tighter for fast double taps.. none of the others had as much muzzle rise as mine. I just got a 308 carbine spring from taccom, if that doesn't work I might try the 308 rifle spring, thinking that the buffer is slamming into the back of the tube causing my issues.. Thanks for the feedback.

Thanks HoMiE, I'll definitely try the subsonic ammo. Not ready to part with the buffer system yet and not sure how much changing the comp will help. Also thinking about staking the castle nut, there also might be an issue with the threading on the buffer tube. I like the idea of the loctite, I'll try that out. Really appreciate your feedback.

Current build parts: - QC10 receiver set and bolt (weight not removed) - Taccom 3-stage PCC Buffer assembly with rifle spring (spring it came with) + Short stroke kit - Standard mil-spec buffer tube carbine length - KVP 16" barrel and KVP linear comp - Taccom CF handguard - Strike Industries Viper CQB stock - Hiperfire Reflex trigger - Using factory ammo (currently winchester 9mm 115 and 124gr, will experiment with different types soon) - Using 10rd (California) Glock OEM and ETS magazines Issues: - Castle nut gets loose after about 50 rounds even after proper torque - Quite a bit of recoil and muzzle rise, would like to shoot flatter. Double taps are far apart. - Out of the ~400 rounds fired have experienced a handful of failures to feed, I'll blame the new stiff magazine springs.. Considering: - Changing the buffer spring to a Taccom 308 Carbine spring - Replacing the buffer tube (need suggestions) - Replacing the compensator with Taccom 2 port short compensator to direct gasses upward - Wondering if the lightweight CF handguard is contributing to the muzzle rise - Wondering if the stock is not gripping well, experiencing muzzle rise no matter how good of a cheek weld, grip and stance I have. Various shooters also experience issue. Wondering where I go from here, overall its a very fun gun, just trying to optimize it for competition and maximum enjoyment and hoping for some good feedback from the community. Many thanks in advance.

Thanks HoMiE, that was very helpful.

Wanted to keep a set of spare parts for the QC10 bolt but can't find any QC10 replacement parts so wondering what the community uses. Saw that Taccom has a replacement firing pin and extractor set and was wondering if it was compatible. Thank you!

Ive ordered a hiperfire reflex and was wondering if anyone had opinions about using red springs vs green? Will it effect reliability or operation? Thank you.

What is the best way to sight in for PCC? I'm using a Holosun 510C. Suggestions for sight in paper targets, distance, etc.

Thanks for the info @tnredneck +1

Good info @tnredneck thank you, any PF, FPS stats i should be looking at?