MemphisMechanic

I’m running a 95lb/in wave spring ordered off of Amazon in the back of the buffer tube with two turns cut off. Then a kynshot .308 hydraulic buffer (5oz, standard cabine length) and Sprinco red Enhanced power buffer spring. This is one flat shooting rifle, although it’s a CMMG Guard so it’s different from a purely blowback gun. The wave spring is cut down to let me manually lock the bolt back, although barely. The Guard has a longer 5.56 length bolt carrier, so I run the shorter carbine-length hyrdo buffer instead of the 9mm Blitzkrieg version

You’re shooting in Open 10 minor.

Not having mags or ammo on your person also makes the RO’s job easier. If you are at the safe area with empty mag carriers on your belt, then the RO can relax a little more. If you just showed clear to him then walked over to the safe area to look into a malfunctioning gun (with half-full mags on your hip) he has to pay a little more attention.

Thanks! Indoors I wish I’d used more black for more contrast. At an outdoor match it’ll probably look perfect.

Thanks Rowdy! Very happy with it. And with the 6lb 1.2oz weight that is all in back. Shoots MPX-like with a well tuned buffer system. Cerakote, yes. Sandblasted and sprayed with an HVLP gun in my garage because I like cerakoting things. Baked in my kitchen oven... because I’m not married. Cost? We won’t be discussing that. Everything is the most expensive option, and a couple pieces had some custom machining done. I could build this again much cheaper, but this gun in particular? I could have bought a JP and had money left over. Thanks! @bmiller made it. Best option on the market! Ships fast, fits perfect. Loads smoothly! I had never tried to reload a rifle before: I have a DeltaPoint Pro 2.5 in my safe. Have shot guns with quite a few other quality options, handguns and rifles. The 510C is the best dot I’ve tried on a rifle for competition. It’s window is huge, its crystal clear, and the battery lasts forever. You also don’t need to mess around with risers.

That’s only a fair comparison when both rifles have had proper testing done to match spring/buffer/ammo to the gun. Mine can rise 4” above the target when I fire if I use the wrong spring and buffer, or leave a snakebite in the A-zone when you rip the trigger twice... if I swap in a hydro buffer, wave spring, spacer, and heavy buffer spring. I’d love to shoot a gun with the ULW setup which had an equal amount of testing done to match my own ultralight 16” barreled gun.

Screw on rubber feet from home depot on each leg of the bench. And trust us: screw your bench into the studs in the wall. The improvement is huge. You’re taking a prybar (the handle on the press) and torquing the bench up and down, in and out, thousands of times. Anchor it to the wall. Even if your bench is huge, like mine was.

@RaylanGivens what do you prefer about full length barrels over the taccom stubby? I made the same decision you did, but havent had time behind a taccom ULW barreled gun yet.

I have the usually reliability testing and buffer/spring/ammo tuning left todo, but otherwise she’s done. Highlights: CMMG Guard upper with forward assist shaved because I’m a lefty and it destroys knuckles. Doing it again, I’d buy a slickside and use the CMMG bolt & barrel. QC10 colt mag lower clearanced for the Guard upper. All magazines have their mag-release notch moved higher in the tube to lower the feed lips to clear the Guard bolt. Barrel turned down to .625” and shortened to 16.25” with surefire brake pinned & welded. This took exactly 1/2 pound off the weight of the bare barrel. Brigand Arms handguard. 4.6oz with barrel nut. Enlarged the ejection port massively, before cerakoting the gun last night. Finished weight: 6 pounds 1.2 ounces. Center of gravity is the mag release button and I love the way it swings in transitions now. Finished it with a very subtle custom “ghost” camo cerakote scheme. The gun looks solid tungsten unless the light hits it just right.

This is kynshot’s 5.0 oz buffer which is the exact same length as a factory carbine buffer when compressed. The CMMG Guard uses a full-length bolt just like a 5.56, so if you put the long 9mm buffer in... it has a very, very short stroke.

That’s pretty much the definition of an unsafe gun, sir.

I like the way my 125s feel around 140ish pf so far, too.

My solution for a lefty mag release was to buile a frankenGuard with a colt-mag lower. Share pictures of your invention, I’m curious. I’ve got the mag release off the MPX installed because it was the cheapest ambi one I could find in stock. Works perfectly.

Good to know. Were you using the 9mm blitz buffer? I’m running the .308 one from Kynshot directly, which is the standard buffer length.

I just added a wave spring to my FrankenQC10Guard rifle. Looking forward to shooting it soon to see how it changes. I’m using a carbine tube too, and the gun has a VERY short stroke - nowhere near locking back. I haven’t shot it de-stroked yet, but in general on other guns? It seems the heavier and shorter you go, the flatter it shoots. In very... VERY... general.

All stock IIIs are “Aussie” models, @Trinimon. They all have 5” barrels. It’s the otherwise 4.5” Stock II where you need a special AUS model to get a 5” gun.

You have to give yourself a little more slack with these issues at majors, as they’re direct results of only having shot the sport for 1-2 years. Experience is the greatest teacher, and most of our skill at breaking down future stages comes from failing to find all the targets, or see the most efficient path, or choose the optimum engagement order... etc... If you seriously think about it, you’re making similar mental mistakes as most of the guys who are 1-2 years in. You’re just beating yourself up because those C class guys are supposed to make these mistakes, whereas an M/near-GM is supposed to be beyond them. I’m not saying to accept them; work hard to slaughter them. All I’m saying is... don’t be so discouraged at their existence in the first place, because it’s an inexperience thing. And you will defintely gain that experience.

The light polymer to heavy DA/SA transition is not an easy one. It’s shockingly hard. Dryfire, and more dryfire. Every day for just 10 minutes (if you can manage it) is far more helpful than 45 mins twice a week. Aaaaand then right when I was shooting the metal gun better than I ever shot plastic... I went back to plastic. You should probably skip that part.

What @Steve RA said. Part of the reason I prefer 125s over 147s is because I can load them to 1.095” to chamber in EVERYTHING and not worry about pressing them back into the case far enough to cause bulging and deformation.

I’d start with the tried and true .308 rifle spring and blitzkrieg buffer. The A5 tube is obviously longer, you can simply stack quarters to de-stroke the bolt until you’re happy, or make/buy a spacer to do the same... ...or get sophisticated and run a wave spring behind a quarter or two for the buffer to impact. That’s the setup that I just installed but have not tested yet. (My gun doesn’t have an A5 tube, however.)

That is a great idea! I keep a container of PB Blaster (a close cousin of kroil that works nearly as well) on my bench to soak my PCCs comp in overnight, muzzle placed in a jar. I use PB because it works like kroil, and is avaiable by the gallon from home depot. You just saved me the “and then scrub out it the next day” part. I’ll give this a try.

Soend money and time on amm and live fire and maybe a class from a good GM. You’ll quickly begin stomping the guys who spend it comstantly switching guns.

Also another thing to check, since I’ve had mine apart getting ready to cerakote it. The chamber is extremly short. See if your current load plunks and spins. The 125gr BBI that I usually shoot it very short-chamber friendly. It’ll run at around 1.125” in a CZ, for example. I had to shorten it up to 1.095” for this barrel. We’ll see if the helps... but I also enlarged the ejection port massively, so I’ll never be certain which ones was the fix. Assuming it doesnt still malfunction.

I have never talked to a guy who is competitive at the highest level (or even local GMs) who didn’t put in a dozen times more practice than your average shooter does.

@cking what are you running as far as buffer and spring? I dont have any issues with the factory setup; when I slowed the bolt down to flatten the gun out with a heavier spring and buffer? That’s when my problem appeared. I think. Same issue you’re having: an empty case didn’t clear the port and is smashed and stuck in front of the bolt while it strips (and otherwise successfully feeds) the next round.