supertux1

$23.74 actually. https://www.opticsplanet.com/precision-armament-accu-washer-muzzle-device-alignment-system.html When I bought my brake, there was nothing in the product page or online literature that I could find to indicate that it came with anything to mount it with. I don't have any 5/8" shims, crush washers, peel washers etc... in my parts box as this is my first large AR. Are you with me so far? I don't claim to know everything about everything, there are large frame things that I've learned as I go, and will still learn, but I do know how to build AR's and I know how to shoot. (I did not get the brake, pull the peel washer out look at it, laugh at it, throw it in the garbage and rush out to buy the shim kit because I got brainwashed by marketing and don't know better, but that's a really funny narrative. ) I bought the brake and five minutes later I bought a bunch of other stuff on Brownells and figured I'd need shim kit. A few days later, I get both in the mail. Now, I have a shim kit in one hand and the brake in the other, and much to my surprise a little peel washer falls out of the package. Now I have a shim kit in one hand and the peel washer in the other. This was unexpected. I figured that I would use the peel washer, because that's what the instructions said. I'd save the shims for the 308 upper that's coming next. So I sliced the peel washer a bunch of times to figure out the best width and that got kind of annoying because I couldn't really get it the width I needed it to be to clock right. So I put the mangled thing aside and broke into the shim kit. One and done. Can you guys ever forgive me for my mistake? There's a fucked up peel washer as the only casualty of this build. I will give it a good burial for you guys. Also, I don't really care if the military does it this way or that way. I am not in the military and I get to choose whatever I want in my rifles because it's my dime and not the taxpayers. Your Mk12 Mod 0/1 is a designated marksman rifle built to a specification for a specific purpose with cost and reliability being important factors as well as long range accuracy. I don't have those constraints.

Of course, it's not free, but don't you think if I'm paying $125 for a muzzle brake, another $1000+$200+waiting for the suppressor that threads on to it, they could, at the very least, include something that would guarantee precise clocking and reduce the possibility of a baffle strike? (Like those $20 PA shims 98Z5V linked.) I hate it when companies do things like this. Here's a really expensive part that doesn't include the relatively cheaper thing to make it work the best. Like when you open up an expensive premium electronic product that takes batteries and there are no batteries, or they're the crappy kind. Some bean counter at work there...

Again, I didn't suggest anyone do this. Only that it's fairly easy to find a source for shims (small discs of metal with varying degrees of thickness in whatever alloy you want) if muzzle brake manufacturers really cared to and it wouldn't cost that much in volume. McMaster doesn't make them, they're an engineering supply reseller, they get them from somewhere, probably China.

I didn't say they were cheap, only that they exist, and that places that aren't competing firearms manufacturers are making them. Want me to put a quote request out on Alibaba.com? We could probably find someone overseas willing to take orders for a million of them.

Here you go: https://www.mcmaster.com/#shim-kits/=1de371r

It's not the combo, I haven't put the paperwork in for the can yet. The one I want that works with this brake is out of stock. You know that my argument isn't 'Why didn't TB put in their competitor's parts!' right? I was honestly going to buy the ones the member linked above, but then I found GEMTECH's cheaper on Brownell's and I was buying stuff from there anyway. I'm shaking my head and giggling that you're all giving me crap about $4 shims...

Ok, let's start. Exhibit A) I bought the brake from silencershop.com. Here is the product page. Show me where it says it comes with anything to mount it. https://www.silencershop.com/thunder-beast-cb-muzzle-brake.html Exhibit B) Scroll up, a member suggested I use a shim kit for brakes that will be used in conjunction with a can. Maybe they're full of poop right? Hmm, the product pages for all the various shim kits suggest this particular use. But their business is selling shims so you know, huge conflict of interest here. Exhibit C) I have found a solution! I used that $4 item as a Brownell's filler item to get a discount and free shipping. $200 = $25 off and free shipping. Do I need to show you guys the receipts?

This is the kit I used: https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrel-hardware/washers/shim-kit-for-mounting-flash-suppressors-prod103512.aspx It cost $4. Here is what it says: "The GEMTECH 5/8-24 shim kit is ideal for mounting flash hiders, muzzle breaks or suppressor mounts. Crush washers and split-ring washers can cause canting of any brand of suppressor. By replacing those crush washers with a precision-made set of GEMTECH shim washers you can achieve perfect alignment and timing. " Did I get fucked out of $4 on something that might not be 'better' but certainly isn't worse? Who do I call?

That's great, now put a 5.56mm in it and pull the trigger. You know, the round you made these claims with. ?

I was under the impression that one shim of the exact thickness needed is the best way to mount a muzzle device that will have a can screwed on to it, and that for such an expensive part the manufacturers could include a $5 kit. Flash hider, who cares, $1000+ part, why a cheap peel washer that looks like crap and deforms?

Done. Notes: bolt/barrel checks out with go no go gauges. loads snap caps from magazines just fine, ejects good too. Feed ramps line up. No rattle anywhere, upper/lower is solid thanks to the special set screw in the M5 lower. 20 round mag doesn’t touch the table with that bipod and grip. I went with the Atlas after all. The muzzle brake came with peel washers which was odd considering it’s for a can. I used shims and clocked it to less than half a degree. Thanks for that suggestion! Rocksett on brake and gas block screws. Blue loctite everywhere else. Gas block is a JP two piece adjustable with six screws. Easy to get at through hand guards. The bottom part had a hole that lined up with the dimple in the barrel but it wasn’t threaded and came with no screw. I threaded it with a 8-32 tap and put a stainless steel set screw in there after filing the tip down to engage the dimple. Used the cheaper reaction rod to torque barrel nut, and brake, vertically. lapped the upper receiver face by hand, just enough to take the anno off and square. It was not square from the factory and there was wobble. Gone now. Receiver extension isn’t as tight in there as I hoped it would be, eg requiring heat and press fit but I think it will be ok. I need to get an optic on there. Probably the Burris or the Bushnell with the Horus reticle. Still shopping... Barrel break in will be done with a cheap ‘scope shaped object’ or iron sights. Thinking about putting on the magpul 45 degree low profile ones. Rifle weighs 12 pounds as you see it, unloaded no scope.

Aero Precision is sending me replacement parts (M5 Upper, LPK) for free after FedEx denied the theft claim. They're out of PMAGS so they are refunding my credit card for those. They didn't have to do this. Stand up company. I will be buying a completed 308 upper from them when the 6.5 CM is done.

I've messed with ones that were hand loaded specifically for the chamber they were to be fired in, right up to, and into the lands.

So you are claiming you've got sub-MOA @ 850 yards (8.5" groups or under) from a 5.56 when a little ballistics math shows that even a mild wind is going to throw that exact bullet and load off 24" left or right at the target? (That was why I posted the other bullets, for comparison, because I find it hard to believe you can group as you say you can.) I have no doubt you can hit a target of that size more than once, eventually, -it is still supersonic and stable-, but unless it's a perfectly nice day at the range I don't see very many tight sub-MOA groups happening. It doesn't matter if you shoot the thing out of a golden barrel blessed by Jesus himself with the finest powder packed up to the neck, it's still a tiny inefficient bullet going through all that air. If that's what you like to do, more power to you, I would just like to try something else now.

Good to know! I'll pick a set of those up. ( I was looking at those when I was considering the M4-72 )

How big is the target and what are your groups like? Does it have feeding issues with those big bullets? I've seen some long 77 grains that are amazing out of a 1:7 twist, but need hand chambering. That bullet is gonna drop 240 inches @ 850 yards and with a 5mph crosswind, 23" left/right drift. 270ft-lbs. .308 Hornady 178gr HBPT @ 2600 fps drop 252 inches @ 850 yards. 5mph crosswind, 17.5" left/right, 770 ft-lbs. 6.5 Hornady 147gr ELD @ 2690 fps drop 204 inches @ 850 yards. 5mph crosswind, 11.5" left/right, 946 ft-lbs. Edit: To be fair, the .308 barrel is going to last longer.

You bought the extended warranty too didn't you? Salesman told you it'd explode and you'd be homeless if you didn't right? ? So I ended up ordering the rest of the parts to complete the upper: Proof Research PR10 Carbon Fiber CamGas 22in 6.5CM Rifle + 2" + gas tube. JP Enterprises RC Handguard for DPMS LR-308, XXL Length, Black JPHG3-7D-RC JP Enterprises Tactical Rail Kit - 2-inch Front Sight Tactical Rail JPTR-FS JP Low profile .875 2-piece Gas Block JPGS-10D Thunder Beast CB Muzzle Brake (going with the Thunder Beast can) Going to pick up some headspace gauges, crush washers, bore guide etc... other bits and tools as I need them. I found a shitty red dot and a mildot scope in my parts box from an older rifle that will be ok for 100 yards barrel break-in. Picked up some 6.5/.260 jags and cleaning rod from Cabela's last night.

Finished the lower tonight. LPK didn't come with safety selector detente (no, I didn't launch/lose it) so I borrowed one from an AR-15 kit. I launched the front takedown detente, but it bounced right off the window and into my lap. :) (Interesting way that one goes in through the front as opposed to the AR.) Basic function tests work ok, nothing out of the ordinary. Silent captured spring is smooth, heavy bolt carrier group slams forward with authority. Coming in at 6 lbs 2 oz. unloaded no optic, no barrel or handguard yet. Add 3lbs for PR 22" 6.5CM barrel, 1 lb for the XL JP handguard rounds it out to a little over 10lbs Add 5pounds for bipod and optic, this is gonna be one heavy sucker. :)

Good to know. Based on this, I am strongly considering one of the JP blocks which is restrictive only and will probably fit better under the handguard I want from them.

I think it's for specific suppressed applications where your support hand location / thermal optics aren't going to be an issue. Probably okay for bench rest shooting in the day time with your support hand under the stock or on a vertical foregrip, but would probably suck for applications where your offhand is on the guard over the thing, or if you mind cleaning fouling from yet another part of your rifle. (The last part doesn't really bother me so much, tools not jewels.) That being said, this is a part primarily designed for AR-15's and not our large caliber applications so there's always that. This guy did a lot of testing with it, fully semi-automatic and suppressed, albeit on the small frame: JP's blocks, similarly priced and engineered for 308 do not feature this bleed off capability,

I asked them a lot of details about suppressed applications with their camgas length, what is known to work with their barrel. Proof said that a lot of their guys used that specific one on their personal setups. Got back to me quickly and answered a lot of my questions. Good to know that it might not work for all 308 applications, but hopefully I can address any cycling issues with the wide variety of springs and weights.

Yeah you guys are hilarious! Arrived today: JP HP Enhanced Bolt JP Heavy VMOS JP Heavy Silent Capture Spring Extra steel weights and springs to tune. After talking with the fine folks at Proof they recommend the Superlative Arms adjustable gas block and the head spacing with that bolt won’t be an issue. PMag, Upper and LPK will be here tomorrow. I’m starting to think this is going to turn out like a JP-LRP07, but with a better trigger and barrel.

Yeah - I hear you, the order there is listed as more of like a priority list, not a list of must-haves -- such a rifle doesn't exist, so there is always a compromise somewhere. That being said, if there's a part that works with all three uses, or does one well and another case acceptable, then it gets consideration over a part that works with only one or two, even if it is a bit expensive. Buy once, cry once. The Proof CF barrel has my attention because it purports to have all the same internal ballistics (or better) than a traditional heavy steel barrel while only having %60 of the weight or something like that. That fits the bill for 'precision' on the range, but also maybe not a pain in the ass to lug around for 'animate' targets... What didn't you like about it, besides the price? I am definitely going to take your advice and build a shorter barreled .308 upper after this build is done. (It may work out that I have an extra upper anyway, due to my first one being stolen from the mail. Grr...)

Yes, iron sights. I don't really count 5.56 a real long-range precision projectile but some guys have a lot of fun accuratizing their AR-15's and what not. It is certainly a good caliber for the ranges around here. I'd rather spend the money building a large frame rifle that can shoot more ballistically efficient rounds and is more appropriate for hunting which I'm just getting into. There is a 600yd range in Columbus, but that's a club and I've only ever shot there as a guest. They're really strict about the use of their long range (nothing less than .308 and training is required) and it isn't always open. They want RSO supervised long-range shooting, which is understandable. The one in Lodi is Winnequah Gun Club and they are the private fancy one with the 1200 yard range. I'm hoping to get in there with a referral from a service member. I was doing ballistic calculations with 6.5 CM ELD bullets and 1400 yards came up as the max supersonic range so that would be perfect. (Members also get a discount on Vortex optics which I'm told is more than the price of the membership. So we'll see. There's a waiting list.) A little further away is McMillan Sports Center which offers a 300 yard public range, but they want $30 a day or $400 a year membership to shoot there. A little steep and far away but currently the best medium-ish range option for most folks unaffiliated with a club. I've shot my AR there and I'm getting bored. Not too far away, the DNR is building a brand new fancy 100, 50 and 25 yard public range which is supposed to open this summer after they fix the damage recent rains did to the berms. That'll be great for scope sight-in and zeroing and coppering up a brand new barrel, tuning the gas system, 100 yard trick shots, one ragged hole etc... There is also the Dane County Law Enforcement Training range which is 100 yards and open to the public on weekends for $10. The 800 yard shooting I've done is on an acquaintance's farm up north, private land, no benches, just dirt. Usually, we lay on the ground or in the bed of a truck and shoot at random junk, steel etc... I do that a few times a year and get use a borrowed Remmington 700. I've been hunting with that too, so now I'm basically hooked on the bigger calibers. ?

300 yards with 5.56 800 yards with .308 We don't have very many public 'long ranges' here beyond 300 yards (like 2 maybe) but I may be getting a private membership to one that is 1200 yards. (On the waiting list.)