Nobody has them in stock. You can call Capitol Armory and get on the list. I did it last month.

I'm guessing you mean AEMBs.
Cursory scrolling shows stock at Brownells. I tried once but they sent me a 1/2x28; you might have better luck.

Yes, that’s what I mean. One site I was looking at had it listed as AEM5 and that stuck in my head. Man Brownells wants a lot for it. If ADCO had it in stock it would almost be half off.

PRI has 6.8 MBs threaded 5/8x24, OOS but you can back order them. I'm using one for my Grendel build.

https://www.precisionreflex.com/Detail.aspx?PROD=186717&CAT=4212

They do ship with a short collar so be prepared to order a long collar if it is an issue. I got one from ADCO.

That's too sweet!  How on earth are you guys getting complete issued Mk12s?!

I appreciate the picture.  *Hurries to go see if my new old stock PEQ2-3 has the wings on the logo...*

Quoting my own post here in order to provide an update in hopes that the following info will be helpful to those who are as confused as I was with the whole barrel/gas block/collar fitment issues.  I talked with Ron Allen @ Allen Engineering, Tony Holdren @ PRI, and Kevin @ HCS yesterday trying to get to the bottom of it.  Got some GREAT info that really helped me understand what was going on.

First and foremost, it turns out the reason the long collar hits the Mod 0 front sight/gas block is that the original barrel specification called for a slightly longer distance from the muzzle to the shoulder where the collar butts up against.  It was "supposed to be" 2 3/8" or ~2.4" to allow the suppressor to get 5-8 complete turns on the brake before stopping against the collar.  However, due to some strange political reasons and circumstances involving another company who was upset about OpsInc getting the contract, they decided to go against Ron Allen's recommendation and instead made this critical distance ~2.2".  This is why all the military-issued guns had the suppressors get only 2-3 turns on to the brake.  Both Ron and Kevin @ HCS said that despite the efforts to screw OpsInc and "make it fail," they couldn't.  The military saw no real issues with the suppressors getting only 2-3 turns.  That being said, 5-8 turns is still preferred for obvious reasons.

As for how military armorers went about solving the issue of the long collar hitting the PRI front sight on the issued Mod 0 rifles, it is suspected that they went about it a few different ways.  Most likely shortened the long collar by simply turning it down on a lathe, while others may have said screw it and butted it up against the front sight even though the collar wasn't fully seated against the shoulder/step on the barrel.  At the end of the day, they just "made it work" and there was no real standardized "short" collar from the factory.  This info may or may not matter to you if you happen to have an issued take-off barrel like I do and were trying to avoid the short collar for fear of your clone looking "incorrect."

Turns out the barrel offered by HCS (and likely the other companies offering aftermarket barrels) adds a little length to the OAL of the barrel compared to an issued Mk12 barrel.  This allows their barrels to work with both the Mod 1 low profile gas block as well as the Mod 0 front sight/gas block without having the long collar run into it.

The position of the milled flats and/or dimples and gas port have never changed.  The gas system is a Colt rifle length gas system.  Period.  All dimensional discrepancies/inconsistencies lie forward of the gas port i.e. the location of that shoulder/step for the collar and the OAL length of the barrel forward of the collar.

The spacer/shim you see in the pictures I posted above is NOT required to align the gas block with the milled flats, dimple, and gas port.  The set screws on a Mod 0 gas block will take care of alignment as they are tightened into the flats and the bottom set screw is tightened up into the dimple.  However, the spacer is optional to "make things easier" and probably makes more sense to use with the clamp style Mod 0 gas block where you would simply slide it on and butt it up against the spacer before tightening the clamp screws.  Something that didn't make much sense to me, however, was when Tony @ PRI tried explaining how the spacer was the same width as the handguard cap on a standard M16/M4 barrel assembly and this spacer was intended to replace the gap created by removal of the handguard cap.  I'm confused by this because I'm not aware of M16 barrels being turned into Mk12 barrels.  But maybe they were at some point early on before the Douglas barrels with PRI front sights became the norm?  Anyone ever seen a Mk12 with a standard A2 FSP?  I'm thinking there must be something to this because otherwise it would make no sense to not have the Mod 0 gas block butt up directly against the 2nd shoulder/step on the barrel.  This little gap between the 2nd shoulder and the rear of the Mod 0 gas block doesn't really need to be there, but it is...

So what am I going to do after learning all of these details?  Well, right now my plan is still to send in my take-off Mk12 barrel to Compass Lake Engineering so they can replicate the chamber specs as closely as possible to the real thing when they turn my new barrel.  Getting the chamber correct is the most important detail in my eyes.  As much as I want to replicate the rest of the barrel 100%, I think it makes most sense to have them lengthen the OAL a tiny bit (like HCS does with their barrels) so I can run the long collar without having to trim it.  I don't want to run the short collar because it doesn't "look right" to me.

I'm still debating whether or not I want to leave that gap where the spacer is seen in my pictures (between the 2nd shoulder and the rear of the Mod 0 gas block).  Now, I don't have a Mod 1 gas block on hand, but I'm thinking that gap just might be there to accommodate a Mod 1 gas block in the event it seats further to the rear than the Mod 0 gas block.  Can anyone confirm whether or not the Mod 1 gas block butts up against this 2nd shoulder or can you still use the spacer?  Can someone also confirm that the 2nd milled dimple on the underside of the barrel (the one forward of the dimple that is there for the Mod 0 gas block) is indeed there for the Mod 1 gas block?

Thanks in advance if you can answer my last 2 questions, and I hope all of this info was helpful for anyone new to the Mk12 game who was as confused as I was!

Cheers!

No, but their relationship with the FSGB has on PRi's side.  The flat location on the issued barrel corresponds with early PRi sights that are made to sit deeper than current. Deeper meaning right up against the block versus space for a handguard cap.  I haven't narrowed down the year that PRi changed.  You may want to consider shifting the flats location slightly on your repro barrel as the vast majority of sights out there will be like the one you have in your hand versus the type that was used on the actual rifles.

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Issued Gen I for this example, but the Gen 3 sights were the same. Looks a bit more pronounced thanks to the rounded legs. I just don't have a loose one on hand to use for the picture.

I see what you're saying, but I noticed in your previous post/reply, you mentioned the set screw on the current production PRi FSGB are centered in the leg instead of forward-biased like the one you pictured.  However, my current production FSGB actually has the set screw towards the front of the leg just like yours, which is inconsistent with what you are claiming.  My set screws all line up consistently with the flats, dimple, and gas port as well.  I can't change the location of the flats on the repro barrel because then the set screws won't be lined up with them when the gas port is lined up.

The only thing that doesn't jive is the position of the ends of the legs relative to the shoulders/steps for the collar and the one behind the FSGB.  This is what is causing the collar to make contact with the FSGB and also why there is that gap/space behind the FSGB.  Perhaps that is what PRi changed and what you're trying to describe?

Many thanks for the reply and visual!  Cheers!

I'm probably being a bit on the misleading side. No one will ever accuse me of being an eloquent typer.

The difference between the era of sights center of gas port holes is just that spacer's width, so I should have added the word more when I describe the newer ones as centered. OAL on the sights seem to be the same. Just the gas port and roll pin holes are shifted slightly forward, with the issued sights installed bottomed out on the shoulder. If you had the two side by side, preferably before they started using the bottom hole as an additional setscrew, it shows it better than I can describe it.

Glad to hear the flats on the issued barrels work with the current sights. I've had issues in the past between different PRi sights on barrels with less generous flat widths, so you could say I'm jaded.

Now I got you 100%.  Makes sense.  Ugh.  Why the heck did PRi have to change things up on us?!  Now, getting that new barrel made isn't going to be as straightforward as I thought it was.  Sounds like I'll need to send my FSGB in to Compass Lake Engineering so they can use it as a template for getting everything to fit and align perfectly.

Thanks again!

Anyone have a spare Leup Mark 4 M2 dial they're willing to part with?  I guess I can call Leupold and try ordering from them but checking here first.

TIA!

And for a pic, I have to give props to HaveBlue83.  He did a set of Arms 22M's for me and was so good I had to do a double take to see where he had milled those awful lever stops away.  Thank you kind sir!

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Anyone looking to get rid their Leupy mk4 3.5-10 m3 illum mildot reticle ? Looking for one to complete my mod H build.

JonnyMoses has one listed in the EE.

Yea I saw one thanks,  thats a bit too much for me $$

***Found one***

Anyone have an black Docter MRDS that they want to get rid of? I am looking for one for my Mk12 clone.

Working on stripping all the Rust-oleum in preparation of the new lower coming in.  Man that is a bitch.  

Its getting there...

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I just fully disassemble and spray with citristrip. Bucket of soapy water and toothbrush to remove.

This is the way.

Citristrip will even remove the black wrinkle finish crap that SAI used on real USGI M14 stocks. I've done quite a few.

Thanks for the tip.  Never used Citristrip.  Gonna see if I can pick some up tomorrow.

Is it safe to use on the A1 grip and stock too?

It's plastic safe for the most part.

I've used it on fiberglass stocks and left it on overnight with no damage.

YMMV.

Biggest selling point, besides ease of use, is that you can rinse it off in the sink and not have to worry about the enviro-nazis showing up (it's biodegradable).

Anyone have a set screw version PRI front sight base/gb you don't need?  Checking here before putting in an order with PRI.  Also looking for a Leupold Mark 4 M2 elevation dial.

If anyone needs a cross bolt PRI front sight base I've got an extra one, feel free to PM me.  

Thanks!

Anyone have a set of medium A.R.M.S. Medium #22 rings? I know this is a shameless plug, but damn I’ve had a ad in WTB, and then I see Johnny Moses had four sets I missed on.

I have a set of new #22 Highs.

0 just got fresh paint

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Nice!  Is that Earth Yellow?

I gotta say, I'm typically not a huge fan of the mod 1 profile, but for some reason yours looks awesome to me.

What's the model on that doctor?

Yeah.  Not nearly as orange as pictures make it look.

No idea

Actually just had a can of that, MC Green, and OD deliver today from Brownells.  Gonna give it a go on the mod H, though just hitting the receivers with it.  Looks good, kinda butterscotch lol.

Took it out for a few rounds the other day, only a few cuz bullets are gold..
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And if anybody wanted to know..the MantisX Blackbeard is pretty neato

Please tell me you didn’t forget a bcg and leave the trainer in the gun.
I’m super jealous all I need in a phone call from HCS to get my barrel on the way. Then the long job of load development starts to match some Mk262 after I get a hand full to check MV’s against.

Hey guys,

I’ve been lurking here since this thread was started.  Finally have a rifle to post, but now I’m having second thoughts about its clone worthiness.

I suppose my question is, how important is the roll mark on the receiver for a clone build?  I was completely content with my rifle, until I got to thinking about it.....  My MK12 is a Bravo Company produced rifle; with BCM roll marks on the upper and lower receiver, and barrel.

I have assured that all other components are clone correct.  

Additionally, I discovered that the collar step on the BCM barrel was off by .100”, and Mr. Allen is making me a custom collar to properly align my AEM5.

The question to everyone here is, would it be acceptable to call a BCM MK12 Mod1 a clone?  

Thanks so much for your time!

Thanks!

no prob, good looking rig

Interesting photo posted today. It looks like a PRI hand guard, possibly a mod h? Probably an older Ops Inc can. Cool to see these are still in use/circulation.

Just a quick update for all of my fellow bore guide nerds. I just got a call and they should be ready to pick up from the machine shop tomorrow afternoon, with all that's left being the engraving and anodizing. Unfortunately the delay with them came from bigger jobs at the shop overriding this project, but we're just about there. My initial estimate of shipping early next week is probably going to be bumped back a little bit, but I should have these things out soon! I'll provide some more updates as it gets closer to the end.

No prob, cant wait for it to get here!

Another image from the same gallery (in stupid high resolution); PRS stock and ambi selector, PRI tube looks ceracoated while the receiver was given the Krylon touch.

https://i.imgur.com/uLJDTK9.jpg

For the thread, a bonus from the same gallery, a Mod.1!

https://i.imgur.com/fn9v0xl.jpg

EDIT: Yes, I intentionally didn't upload the images here for the sake of users data.

Can't wait, this will be the start of my deployment case. Now need just about everything else

Sooooooo, this begs the question could a MOD H be correct using a SOPMOD??  Inquiring minds want to know.

Always has been.

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A couple more. Same rifle I think..
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That sad, unused, ACE.

I let it go.  Someone's using it.

@TXhounddog shoot me an email I may be replacing mine and ARMS #36S-EX with a TS30 to shave some  weight off

What sort of ambi-safeties are generally used on Mod 0?  I've gotten so used to having one on all my other builds that I REALLY want to put on one on my Mod 0.

Although I've not seen an ambi on a Gen 3 Mod 0, DPMS with full size lever is the ambi you commonly see on Mk12s.  Current Luth-AR is identical.