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CMMG Guard vs Blowback PCC with Specialty Buffers


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Now that that the CMMG Guard and various buffer systems have been out for a while, I'd like to get your thoughts about how they stack up. How does the recoil, dot bounce, shot cadence, and overall stage times compare with those who have tried the CMMG Guard versus a blowback 9mm PCC with a specialty buffer system. These include the Taccom 3 Stage buffer, hydraulic buffers, and short stroke systems. Can a blowback PCC with these buffers be made to shoot as soft as a Guard? Or, is the Guard system still the front runner? Thanks in advance for your insight and comments.  

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12 hours ago, MemphisMechanic said:

Softness:

 

MPX > Guard > Blowback 9’s.

 

My gun is guard based, and quite dramatically softer than everyblowback gun I’ve ever fired. That said, I don’t find softness nearly as important as flatness.

 

But it’s a nice fringe benefit. :D 

 

I agree with the parts in bold. I happen to have all 3. With several different buffer combos in the Guard/BB. I will say that the Sig is far and away softer and flatter than the other two. The Guard is softer, but not significantly and I find it no flatter than a BB with the taccom buffer. IMO the Guard was not worth the time time/money I sunk into the build. Perhaps if you were starting from scratch. Also if you're starting from scratch, I'd just buy a factory Guard... but at that point you're damn near/at used MPX money. 

 

Same reason I went taccom over hydo buffer in my BB. Hydro was softer, but slower. Now my Guard build runs the hydro setup... and my wife shoots it. It's key for me to keep the recoil soft for her level of enjoyment. She's not looking to make GM. And yes, Guard + 9mm hydro buffer is soft.

 

Honestly, it's a rifle. My times are only marginally better with one vs. the other and my mental mistakes are what cost me 1st place, not my gun (you know, except when it doesn't work). I like to build/tinker, so I can't help myself, but RELIABILITY is the key to PCC. 

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1 hour ago, Acer2428 said:

...Guard + 9mm hydro buffer...

 

So, what hydro buffer are you using with the Guard?  The Blitzkrieg is 4" and the Guard buffer is 3.25".  Or do you use a rifle length stock plus something else?  I have been using a 3.25 KynSHOT buffer.  And there are different choices there too.

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I used the 4"/9mm specific Kynshot because it's what I had on hand. 

 

I also brought a std. carbine buffer, h1, and h2, and taccom system as well a carbine, rifle, and 308 carbine springs. Softest shooting by far was the 9mm hydro + 556 rifle length spring. There's no LRBHO on the upper (using a 458 billet AR upper) or lower, so I didn't worry about stroke length other than trigger reset. Runs fine. 

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I run a 5.0oz kynshot buffer intended for a .308 carbine in my Guard. It works well in a carbine length tube. Paired with the red sprinco spring it’s damn flat.

 

Tuning the compensator to kill the remaining muzzle rise really got the gun sorted out nicely. I do agree with @Acer2428 on the rest however: the Guard isn’t any flatter or faster than a blowback gun. But then, neither is an MPX.

 

The primary benefit to the Guard so far seems to be something most aren’t bringing up; it’s insanely reliable. Firing pins and trigger groups are practically in the “consumable parts - stock spares!” category for blowback guns. The Guard’s 5.56 style firing pin so far hasn’t had a single breakage that I’m aware of.

 

The slower bolt speed is likely kinder to trigger groups as well. But I’ve thus far stuck to PCC-proof triggers anyway (a KE Arms SLT and a JP) so I can’t verify that.

 

Edited by MemphisMechanic
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  • 2 months later...

Any updates? I just joined this group and I'm looking around. I just put together a Foxtrot Mike's build kit around a CMMG Guard 8" barrel & bolt. From what I understand they're just using a standard carbine buffer and spring now so I just stole that, along with the trigger out of my S&W M&P-15 for the time being. I didn't want to buy parts that I wouldn't be happy with and end up in the parts bin. I've been considering that Armaspec captured system with the dual stage spring, but I'm not sure what weight to try. I put 100 rounds through it last weekend after I put it together without a hiccup even though I haven't yet clearanced the ejection port like CMMG does. I'm wondering if it's even necessary, or if they were just being over cautious?

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5 hours ago, NPDriver said:

Any updates? I just joined this group and I'm looking around. I just put together a Foxtrot Mike's build kit around a CMMG Guard 8" barrel & bolt. From what I understand they're just using a standard carbine buffer and spring now so I just stole that, along with the trigger out of my S&W M&P-15 for the time being.

 

Wave spring.

A single quarter used as a spacer.

Sprinco red spring.

Kynshot 5oz hydraulic .308 buffer.

 

5 hours ago, NPDriver said:

 

 

 

 

I've been considering that Armaspec captured system with the dual stage spring

 

Don’t bother. You can buy my used one if you want to waste your money too.

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11 hours ago, MemphisMechanic said:

 

Wave spring.

A single quarter used as a spacer.

Sprinco red spring.

Kynshot 5oz hydraulic .308 buffer.

 

 

Don’t bother. You can buy my used one if you want to waste your money too.

I've read about the wave springs, sounds great but is that going to allow enough travel for my LRBHO to function? I may have 1/4" travel past the bolt catch tops & to be honest, I wasn't really too disappointed in the performance of the carbine setup. For the time being I'm just plinking through iron sights in the backyard but I will be assembling a rifle length upper and trying to enter some matches come spring with my local range. I have been reading up on the hydraulic buffers also. They seem to be well reviewed by most people who have tried them as far as I can tell. Is a .308 buffer the same overall length as a carbine buffer? I know I was looking at them when I was just looking at building a regular direct blowback system. Sorry for the stupid questions but I'm just getting started here.. I'm just looking for something that will cycle as smoothly and reliably as possible with any off the shelf round. I don't reload yet, I plan to in the future. For the time being I typically just stock up on whatever is on sale. Thanks for the help! Oh! And if you're serious about that Armaspec buffer, I might be interested in it for my rifle. 

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The wave spring will short stroke the gun so that:

 

1) it will lock open reliably for the last shot.

2) you can lock it open. Manually. With a hard wrench of the handle. My 118lb girlfriend can’t manage it. It’s really tight.

 

This setup won’t soften the recoilWhat it *WILL* do is make the gun shoot hilariously flatly. Pull the trigger and the dot barely bucks at all.

 

The 308 buffer is stock length. It weighs 5.0oz versus the carbine 3.8oz. A heavier one might soften and flatten things out more. I haven’t tried one.

 

The gun will run on factory ammo reliably. Reloads will just be softer, shoot flatter, and more accurate once you tune them to your particular gun.

 

 

Edited by MemphisMechanic
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2 hours ago, HoMiE said:

Lrbho is pointless for pcc, it’s not in the correct position and if you are trying to short stroke, you’re defeating the purpose. If you run the gun dry, you have bigger issues. 

I'll keep this in mind when I decide to build an upper for PCC. Until then I'd like to retain the feature in my 9mm pistol. 

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1 hour ago, MemphisMechanic said:

The wave spring will short stroke the gun so that:

 

1) it will lock open reliably for the last shot.

2) you can lock it open. Manually. With a hard wrench of the handle. My 118lb girlfriend can’t manage it. It’s really tight.

 

This setup won’t soften the recoilWhat it *WILL* do is make the gun shoot hilariously flatly. Pull the trigger and the dot barely bucks at all.

 

The 308 buffer is stock length. It weighs 5.0oz versus the carbine 3.8oz. A heavier one might soften and flatten things out more. I haven’t tried one.

 

The gun will run on factory ammo reliably. Reloads will just be softer, shoot flatter, and more accurate once you tune them to your particular gun.

 

 

Thank you for the info! This is exactly what I was looking for. Are muzzle brakes even effective on these things? My barrel ends about 1 3/8 before the end of my handguard, so I'm sort of stuck with some kind of blast can on this one anyway, but when I build a 16" upper does it really matter?

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From one of Memphis’s post in another thread I bought and tested the blitzkrieg buffer 5015hd with the jp 308  rifle spring, jp 308 carbine spring, and red sprinco. I tested all the above with and without a 95 inch/lbs wave  spring and 1/2 delrin spacer. Also tested against my mbx buffer with all the supplied springsI shoot a direct blowback ar9, 124 gr at 1130fps 140.12pf.

 

In a carbine  buffer tube red sprinco, wave springspacer and blitzkreig I had the fastest splits and kept the dot on target the easiest. Lrbho is disabled with this setup. 

 

In a carbine buffer tube, the mbx with the green internal  spring and yellow sprinco was close second. Lrbho works with the setup 

 

I have the 2 oz weight from blitzkrieg arriving Monday to try. 

 

I have a mbx 14.5  barrel with the mbx 3 port comp pinned and welded. A comp definitely helps in the pics I posted you can see one with gases being directed out and there being 0 muzzle rise. ( this was with Memphis recommended setup I changed the quarter for a 1/2 spacer) 

 

63FF2075-EE7B-4CBB-BD8F-53AAF4C147BE.jpeg

AFD126AD-7084-4477-8C2E-163CBD7E972B.jpeg

Edited by Bwillis
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I really appreciate the help fellas, and thank you Memphis for the suggestions! I do try to do my own research before chiming in on anything. I don't want to be known as "that guy" who beats a commonly discussed topic to death, who never reads anything related to the topic they're talking about or searches out answers on their own. I've been watching this forum for awhile and found many of the answers to my question I had for my build on here. My choice of parts was heavily influenced by what I read here. I didn't know the first thing about PCC's a few months ago, now I have a new favorite firearm & I built it myself! So thanks to everybody who writes down & shares their thoughts and experiences here. 

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  • 1 month later...
On 10/10/2018 at 10:03 AM, MemphisMechanic said:

...

 

The primary benefit to the Guard so far seems to be something most aren’t bringing up; it’s insanely reliable. ...


Did you have to change out the buffer and spring to get the Guard reliable? I am having trouble with mine and can use all the help I can get. It was killing the glock mags before going back to CMMG and now they are sending me a new mag catch due to feeding issues I am having. 

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On 12/16/2018 at 1:05 AM, MemphisMechanic said:

 

Wave spring.

A single quarter used as a spacer.

Sprinco red spring.

Kynshot 5oz hydraulic .308 buffer.

 

I have essentially this exact same setup in mine now.  And as has been alluded, the key for me isn't so much recoil reduction as it is muzzle rise.  With this combination shooting factory 115-gr (Blazer Brass in my case),  I get a nice cushion of the rearward 'jolt' but it has a quick cycle so the dot is right back where you want it.  A slower and heavier bullet, though, has a softer recoil/jolt, but the muzzle rises more as the buffer seems to go through a slower cycle.

 

I like this setup now a lot since I get this ammo in bulk locally as I don't reload, and it just stays on target.  I also have the MBX barrel/comp as pictured earlier.

Edited by MoRivera
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4 hours ago, ziebart said:


Did you have to change out the buffer and spring to get the Guard reliable? I am having trouble with mine and can use all the help I can get. It was killing the glock mags before going back to CMMG and now they are sending me a new mag catch due to feeding issues I am having. 

 

I never got the gun reliable on colt mags.

 

I’m 99.9% now on Glock mags but I’m not running the Guard lower, so feeding could be a totally different animal due to mag height and angle... and my ejection port is gigantic.

 

Edited by MemphisMechanic
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6 hours ago, MemphisMechanic said:

 

I never got the gun reliable on colt mags.

 

I’m 99.9% now on Glock mags but I’m not running the Guard lower, so feeding could be a totally different animal due to mag height and angle... and my ejection port is gigantic.

 

I've been meaning to ask you if you use any of the CMMG weights for the bolt itself. I ordered a LaRue MBT trigger yesterday. Now all I need is a Kynshot buffer, .308 spring, and I've been thinking about a POF or 2A Armament AR-10 length buffer tube. I could probably stuff a wave spring covered by a quarter in the extra .75" of the tube, (if it even gets that far) and the little extra length of pull wouldn't be a bad thing.

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4 hours ago, NPDriver said:

I've been meaning to ask you if you use any of the CMMG weights for the bolt itself.

 

Didn’t know they existed, but I also think the lighter bolt is an advantage in felt recoil, and the gun is flat enough I don’t know if it would help enough there to be worth the harsher recoil.

 

Quote

I've been thinking about a POF or 2A Armament AR-10 length buffer tube. I could probably stuff a wave spring covered by a quarter in the extra .75" of the tube

 

I bought an A5 tube. Never even installed it and should probably sell it. I wouldn’t bother.

 

 

Quote

the little extra length of pull wouldn't be a bad thing.

 

Everyone who crushes PCC that I know (including a guy who’s 6’3” with long arms) run the stock pretty short. I run my gun fully collapsed.

 

Running and gunning means it’s advantageous to run your stock short with a more vertical pistol grip, and scoot the stock toward centerline, onto your pectoral directly below the dominant eye. My shoulders stay almost square to the target which is ideal for fast shooting and moving with the gun shouldered. Telecoping the stock out will blade your torso with respect to the target, and push the stock out toward the pocket of your shoulder.

 

Just like getting your offhand way forward of the magwell, shooting with the stock over on your squared chest is really weird at first. Then you won’t want to run the gun any other way.

 

Edited by MemphisMechanic
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