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Compensator?


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Mike is right on -- I tried a pistol comp on my PCC, and it was very difficult to get a 9mm minor round to generate enough gas to do anything. I was getting close to major power factor, and the comp wasn't doing anything. But the bolt was getting more violent with the higher power facter.

So put whatever you like on the end, its just a decoration :-)  ( My PCC is happy .5gr less N320 powder than my normal carry optics / production load. )

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Thanks for the input. I assumed that a 9mm minor load wouldn't generate nearly enough gas to work a comp. I have found a few cheap comps marketed for 9mm, but I might just do a thread protector. Sounds like you get better recoil management/dot flip by messing with buffer springs. Have you found this to be the case?  

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Hello: I am using a birdcage comp/thread protector. I figure it will protect the crown of the barrel and move me that much further away from the barrier for classifiers :lol: When I tested some comps a couple of years ago on a PCC they did not do much at all. Loads, overall weight, bolt carrier weight and buffer setup will do more. But they do make some cool looking ones now with teeth. Thanks, Eric

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43 minutes ago, Les Snyder said:

anyone have a source for 1/2-36 thread protectors?

Xtreme precision sells some on Amazon for $8 shipped. I have used 3 of them and found them to br satisfactory for my needs.

I did loctite mine on so I don't have to worry about it backing off. 

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1 hour ago, PHX said:

Thanks for the input. I assumed that a 9mm minor load wouldn't generate nearly enough gas to work a comp. I have found a few cheap comps marketed for 9mm, but I might just do a thread protector. Sounds like you get better recoil management/dot flip by messing with buffer springs. Have you found this to be the case?  

In my experience with blowback ARs so far the number one improvement I have seen is a true minor load. In a 16" gun this typically takes a significant powder reduction relative to a minor pistol load. Dropping down to the 130 to 135 PF range dramatically improves the guns behavior.

I have done some experimenting with springs, but the next most significant factor in my experience is the reciprocating mass. If using factory loads, or minor pistol loads I wouldn't go much lighter than a "factory" AR 9mm which is somewhere around 21 to 24 oz combined buffer and bolt weight. I am still experimenting, but I think I will settle somewhere around 17 to 18 oz combined weight with my reduced loads.

In terms of spring weight a GI style trigger/hammer and relatively stiff hammer spring (I use the JP Enhanced Reliability spring kit but mil spec works great as well) will help keep the bolt closed initially and allow you to use a lighter recoil spring than you would otherwise be able to use. I am currently at a Wolff XP AR15 spring, but I think I will go back to a factory carbine spring.

Finally, tuning the stroke can also impact dot movement. I have used quarters for this- when I settle on stroke I will do something more permanent.

 

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Mike, Eric... thank you ... I think I've settled on a load that works for my pistol and PCC... not ideal for the PCC, but I can live with it... I currently have a Miculek style 3 port on the PCC... will give a closer look, but most likely will keep it on...I don't shoot super tight clearance matches, so the couple of inches is not usually a problem, and it is already purchased... again thanks for the quick reply

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Thanks for all the great responses. I did settle on a basic thread protector. I can always switch to a flash hider/comp later if I want for looks. I only shoot 40 major in limited for uspsa, so for this 9mm pcc I will develop a specific load for the rifle. The goal will be a 128-132 PF. I'm leaning towards a 124gr Berrys bullet. 

 

Mike. When talking about stroke. Are you talking about the length the bolt travels in the receiver?  Are you stacking quarters in the back of the buffer tube to reduce travel length?  I'm confused how this will help with recoil management/dot flip. Thanks!

 

Now I just need to settle on an optic. I'm in between the vortex sparc ar and the trijicon mro. 

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Hello: He is shortening the stroke and also putting preload on the spring giving more pressure on the carrier. The quarters stop the bolt from coming too far back that it breaks the bolt release. Once you know the distance you can make one from Delrin, aluminum, rubber or steel. Tuning your load does a lot for the recoil and dot tracking for sure. Your range may be a little to close. You may want to try the 131-134 PF range just to be sure. You may want to look at a C-More railway for your PCC. Thanks, Eric

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PHX... I'm not Mike, but a lot of people find that the shorter length of travel produces a quicker cycle time, and lessens the bounce...

re: optic... I'm currently using an out of work TA44 1.5x16, but before that a SPARC II and Spitfire were on my PCC... I have a pretty bad astigmatism, and the ability to focus the Spitfire was an asset, even though I don't particularly like the reticle ... the SPARC worked well and gave me a round dot looking through my distant lens of my bi focals (much better than other dot scopes have done in the past), but lost roundness looking through the near prescription

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Like many here I am in the exploration phase of "what works best for me" and have tried a few loads, a couple of comps, and a little buffer/spring swapping.  I don't have any real conclusions yet, but so far the one thing I tried that I felt made an improvement in the dot bounce/feel of the gun was installing the 7 buck New Frontier Armory Buffer Spacer.  It doesn't preload the spring like the spacers/quarters, but does limit travel so the bolt doesn't travel more than about 1/4" or so behind the bolt catch.  BTW - for my baseline I'm using a PSA lower and with the stock spring and buffer. 

I've tried two comps, one was a 20 buck ebay 9mm muzzle brake that had a pretty nice design and seemed to have a noticeable effect over just a bare muzzle on the dot movement but it is a heavier comp and may just be the weight.   The other is the Kaw Valley linear comp which my upper came with.  i didn't think the Kaw Valley would do much but it seems to tame the dot bounce more that I was expecting and it is fairly light at less than 3 oz.  I'm using fast powders (GM3 and American Select) and lighter (124-135) bullets right now. 

Lots more learning to do and I'm taking the tack to 1) develop a good solid reliable load that give good accuracy out to the 50 yard range, and then2)  tailor the buffer/spring/muzzle brake to that load. 

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On 12/2/2016 at 5:13 AM, PHX said:

Mike. When talking about stroke. Are you talking about the length the bolt travels in the receiver?  Are you stacking quarters in the back of the buffer tube to reduce travel length?  I'm confused how this will help with recoil management/dot flip. Thanks!

I am. Altering the stroke length affects how hard the buffer "bottoms out" in the buffer tube and how long it takes for the bolt mass to change direction.

With the shorter stroke the gun feels (to me) a bit more harsh but there is less overall movement in the dot.

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I've settled on a 148 power factor with the PCC, which makes 128 with the G34... tried with and without the comp today, after settling on the load.. a 3 side port, 3 porpoise hole unit..., there is still a noticeable reduction of scope movement with the comp so looks like it stays

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I put the NERD 9mm comp on mine. A while I noticed very little effect, a little is better than none. I think its good to have one on, if for nothing more than to have the timer pick up your shots.

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PHX... originally it was a GuntechUSA multi port 9mm 1/2 -36 comp... around $40... I did not like the way the slanted ports leaded up, so milled the sides to very similar to a Miculek AR comp... it has 3 top holes...I'm not sure if the Palmetto State comp has top holes, but I think I would look at that one if I had a "do over" for an inexpensive comp... when I purchased the Guntech comp there was not a whole lot of choices in 1/2- 36... I wish the barrel manufacturer's would standardize to 5/8 -24 for 9mm...

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I installed a Custom Muzzle Brakes Tri Delta pistol muzzle brake on my 11" barreled upper and shot it back to back with a 16" barreled upper on the same lower, with the same bolt and buffer, and same ammo. The recoil was noticably softer with the comped, shorter barrel. This was no sort of scientific study, but I could appreciate the difference.  

 

Perhaps in the spring I can try some timed splits and groupings with without the comp.

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