Jump to content
Brian Enos's Forums... Maku mozo!

Colt-Pattern PCC Builds, what is working best?


Recommended Posts

I wanted to share some information/testing on Colt-pattern mag solutions, I didn't want to step over the excellent build thread that @Aircooled6racer has going so here's what I've got:

 

I'm currently working with three builds and components I will be switching back and forth. They are as follows:

 

Platforms:

  • Carbine #1: 16" Kaw Valley Precision barrel on a CMMG/colt dedicated lower with a Spinta Precision slickside 9mm upper.
  • Carbine #2: 16" KVP barrel on a QC-10/colt dedicated lower with a Gibbz Arms side-charging 9mm upper.
  • Pistol: 4.5" KVP Barrel on mil-spec lower using a Rock River magwell block with a Spinta Precision slickside 9mm upper.

 

Buffers:

 

Triggers -- I'm running 2 different drop-in trigger systems. Both seem to work fine with the bolts listed. No reset issues. 

  • POF -- flat 2.5# flat.
  • Velocity -- 2.5# curved. 

 

Bolts:

  • JP Enterprises
  • KVP
  • Faxon ?? This may be a future purchase. I have a 3rd bolt/buffer system I want to buy, but I want to see how these components work before jumping into something new.

 

Magazines:

  • Palmetto State/Metalform/Colt mags -- I have a good supply of these and the LRBHO seems to work well so far. 
  • Modified Uzi Mags -- Once I have some established reliability metrics, I'll throw these into the mix. I have a ton of them, but they do NOT have an LRBHO.

 

Ammo:

  • This will mostly be using LAX Ammo 115Gr, because it's cheap and I shoot a lot of it.
  • If this is problematic, I can look at changing, but I would prefer to be able to run ONE ammo in everything.

 

Edited by bluesman2a
Link to comment

Initial range report:

 

The Pistol was running the KVP buffer and bolt. It ran like a top without a single failure through 5 full magazines.

I *WILL* be SBR'ing this, it's just too fun not to.

LOTS of felt recoil. Too much for what this is. I want to try th heavier buffer in this and see if it makes a difference. Will also throw the 308 spring in as well.

I was surprised the magwell block solution ran as well as it did.

Reliable LRBHO performance.

I also want to try a comp on this, currently it is running the KVP XL Linear comp, I bought it more as a thread protector than anything. I am unimpressed with it's performance.

I will try an MBX, and am open to suggestions on others I should try.

 

Carbine#2 Ran OK. I had several jams with this, currently unsure why or what is causing it. Probably 4-5 out of 5 full mags. Mostly it was with a single mag and once it happened I would get several more strung right together. Empty casings were still in the chamber area along with a new/live round, and to clear them I would have to drop the mag, pull the bolt all the way back and let everything drop out the bottom. Bullets that went through this would have a slight BEND in them where they were partially in the chamber when the bolt closed on them. This is somewhat annoying and I'm hoping I can solve it with a good bolt/buffer/spring combination.

 

The carbine shot MUCH smoother than the pistol. I like the SCS, but I want to make sure it is not the root of my issue before committing to another one. I will also compare this to performance with the HeavyBuffers going forward. 

 

Again, I am open to suggestions on other bolt/buffer/spring/comps and tuning tricks that have worked for others. 

 

Muzzle device comparison. Despite the size, the larger one is actually lighter.

34E5674C-6B77-4E13-845E-AF6E4226A1D0_zpsE6DE2B76-981B-4D96-97A3-8BEF965AC561_zps

 

 

Edited by bluesman2a
Link to comment

On any of these builds, are you able to use a standard mag catch? On my Colt style, I'm using a RRA mag block also. A standard mag catch didn't protrude enough into the magwell to lock in a mag. I had to switch to the RRA 9mm catch. I'd really like to use a Troy ambi mag catch. Not possible on a Glock style, so a dedicated Colt style appears the only way to do it. 

Link to comment
59 minutes ago, OPENB said:

On any of these builds, are you able to use a standard mag catch? On my Colt style, I'm using a RRA mag block also. A standard mag catch didn't protrude enough into the magwell to lock in a mag. I had to switch to the RRA 9mm catch. I'd really like to use a Troy ambi mag catch. Not possible on a Glock style, so a dedicated Colt style appears the only way to do it. 

 

I had to modify a Troy release to allow the mag catch to seat deep enough to catch the mag in a colt dedicated lower. 

Link to comment

Hello: I am using a standard 223 mag catch with a Hahn bottom insert. I think it is an old DPMS one I had in a parts box. Good write up on your Colt based PCC. The bolts I have used so far that have worked 100% are the Kaw, JP, and the Matrix ones. The one that did not work was the Palmetto one that came with an upper that a friend has. Load development and buffer setup will do a lot for dot tracking. Try some 124 and 147 grain bullets also to see what you like best. Thanks, Eric

Link to comment

So I had a chance to take out Carbine#1 today. It worked flawlessly. Zero jams over 200+ rounds.

 

The setup for today was:

Carbine #1: 16" Kaw Valley Precision barrel on a CMMG/colt dedicated lower with a Spinta Precision slickside 9mm upper. Ran the KVP bolt and the Heavy Buffers 9Q buffer.

I also tried the KVP 7.5oz buffer and the Spikes ST-9X buffer which is 8.0oz. There was more recoil as the lighter buffers were used.

I did NOT get to try my extra power spring, as I unintentionally left on my bench in the shop.

 

Recoil wasn't bad but still lots of dot-bounce. I want to try the JP SCS on this setup, but I didn't have the JP bolt with me either. My next step is to try the HB9Q buffer with a 308 spring, and also run a Spinta upper on the QC-10 lower for troubleshooting.

 

In the way of new purchases, I've ordered a Holosun HS510C

https://www.amazon.com/gp/product/B01IIQ5YAI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 

 

I'm also looking at what muzzle device. I was thinking the JP or the MBX. Any thoughts here?

 

From the left to the right:

  1. Spikes ST-9X 8oz.
  2. KVP 7.5 oz
  3. Heavy Buffers 9Q 9oz (notice the taller collar on the bottom. 
  4. JP Silent capture spring in the back.

Springs -- Compare normal Carbine Buffer Spring to Extra power spring, the longer is the extra power obviously.

23D63C54-0E7C-43F4-B04F-1C37B39E621F_zps

Link to comment

Hello: When I tried the heavy buffers I did not like the recoil at all. I went with a lighter buffer and a heavy 308 carbine spring with a plug in the back to limit the amount the bolt came back. For me and my reloads the 4.3-5.6oz range works the best with reloads in the 131-137PF range. Too much weight gave lots of dot lift and dot dip with factory loads. For shooting steel that may not be a bad thing, but for shooting targets with two on paper it was not good. Once you get the setup correct it makes shooting these AR 9mm's quite a bit easier. Thanks, Eric

Link to comment

I did what you're doing and tried a combination of spring/buffer weight/loads.  Kind of what's working for me right now is the Spikes ST-9X, Tubbs Flat wire buffer spring, CMMG bolt (with the weight in it), and a powder puff load that is 132 PF out of a 16" bbl.  I did try a JP SCS, and that was nice.  Unfortunately did not have opportunity to shoot it side by side, but I don't think the two are very far apart.  I played around with the various combo's doing bill drills @ 15 yds and also going by feel to find the combination I liked.  

 

As far as comp, currently using Miculek comp bored out to 7/16".  The comp does make a difference IMO, but I was looking for something that the shot timer could pick up more reliably so the RO doesn't have to be super close all the time.  

 

Last couple of matches I've been playing around with an offset dot in addition to a CMore on top.  I've been finding it easier to get into position for the hard leftside leans (I'm right handed) and also for shooting on the move.  Not sure why, but I feel more stable on the move with the offset than using the upright red dot.  

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...