Problem with build + How to tune (QC10/Taccom PCC Buffer)

[CaliPCC]

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.

[HoMiE]

All of the factory ammo I have shot out of 16” barrel was 150+ pf. I haven’t tried any of the new federal syntech 130gr ammo but that is supposed to be tailored for pcc. Another option is to try subsonic ammo since 16” barrel will give you more velocity than listed.

 

if you replace buffer and spring, blitzkrieg and 308 rifle length spring. The linear comp isn’t helping, I prefer the 2,3 port type that help pull gun forward.

 

Ive had the castle nut come loose with factory ammo until I started to reload for pcc. You could try some blue loctite. 

[CaliPCC]

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.

[CalTeacher]

If you want to tame the recoil then you will need to change the buffer.  A blitzkrieg with a 308 rifle spring and their spacer is really ideal.  Keeping the weight inbuuur bolt will help too.

[Aircooled6racer]

Hello: Try running it with the full stroke to see if it gives you less muzzle rise. Changing the comp won't do anything for your muzzle rise just makes the timer pick up the shots easier. I would also check your ammo in the barrel to see if you have enough throat. Thanks, Eric

[RAINY0DAYS]

A comp won't help much, and the Taccom buffer is pretty good as far as PCC buffers go. A Blitzkrieg isn't going to magically solve your problems. Biggest thing you can do is change your load to something softer and go from there.

As far as the castle nut is concerned, stake it or get a PWS ratcheting castle nut.





Sent from my moto x4 using Tapatalk

[mmlook]

5 hours ago, RAINY0DAYS said:

A comp won't help much, and the Taccom buffer is pretty good as far as PCC buffers go. A Blitzkrieg isn't going to magically solve your problems. Biggest thing you can do is change your load to something softer and go from there.

As far as the castle nut is concerned, stake it or get a PWS ratcheting castle nut.





Sent from my moto x4 using Tapatalk
 

agree, I ran factory ammo for my first 1k rounds of competition 

night and day difference when I started reloading 

PCC's are just like open guns, the load makes just as much of a difference as all your other hardware combined(bolt, buffer, barrel, etc..)

[Startingover]

I run all factory ammo.

(Blazer brass 115gr)

The Blitzkrieg and a 308 rifle spring work very well.

 

[Blockader]

How does the impulse feel compared to other AR PCCs you have shot? 

 

Locktite might help the castle nut but you can try some plumbing thread tape if not. There's even black dope tape now. 

 

 

[CaliPCC]

2 hours ago, Blockader said:

How does the impulse feel compared to other AR PCCs you have shot? 

 

Locktite might help the castle nut but you can try some plumbing thread tape if not. There's even black dope tape 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.

[CookieTheSwede]

I have the same recoil system. Swapping to a 308 spring and adding $2.50 in quarters to short stroke it worked like a charm.  I have the taccom bolt with the weight out. 

 

I had to use blue loc tight on my QC10 receiver/tube combo. Mine kept loosing up as well. 

Edited February 9, 2019 by CookieTheSwede

[CaliPCC]

9 minutes ago, CookieTheSwede said:

I have the same recoil system. Swapping to a 308 spring and adding $2.50 in quarters to short stroke it worked like a charm.  I have the taccom bolt with the weight out. 

 

I had to use blue loc tight on my QC10 receiver/tube combo. Mine kept loosing up as well. 

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

[bwikel]

I suggest you approach it as follows (listed in order of priority);

 

• Don't make any buffer system changes until you find ammo in the 130-145 pf range
• Remove the weight from the bolt to bring down the reciprocating mass of the buffer system
• Find the right spring to match the new load and buffer system weight
• Decide which comp you want or keep what you already have

[CaliPCC]

8 minutes ago, bwikel said:

I suggest you approach it as follows (listed in order of priority);

 

• Don't make any buffer system changes until you find ammo in the 130-145 pf range
• Remove the weight from the bolt to bring down the reciprocating mass of the buffer system
• Find the right spring to match the new load and buffer system weight
• Decide which comp you want or keep what you already have

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.