Pinned and Welded Muzzle Device

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MaduroBU
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Pinned and Welded Muzzle Device

Postby MaduroBU » Fri Oct 13, 2017 9:49 am

I intend to buy a K&M M17s .300 Blk when it becomes available (we're now going on 9 months of "Soon"). My goal is a 26" replacement for the Marlin 1895 and Winchester 1894 .30-30s with which I hunted deer in my youth. These guns come with 17.5" barrels because the OVERALL LENGTH would fall below the minimum with a shorter barrel. The .300 Blackout is standardized around 16", and the additional 1.5" is well beyond the point of diminishing returns for velocity.

I will hand load 150 gr Hornady SSTs for hunting with Lil' Gun (Hodgdon RDC says 2050 FPS from a 16" fixed barrel, so subtract 20-30FPS for the gas system) and 150 gr FMJ-BT bulk bullets ( over either Lil' Gun or, if the reports about it "running hot" prove true, CFE Black) for practice and fun.

I will use a can, and intend to have the same Gemtech bilock muzzle brake on my .300 WSM on this gun so that I only need one rifle suppressor (at least until the addiction modifies my definition of "need" yet again). The 17.5" barrel that comes stock can be cut down to 15" before running into issues with the forend (a single aluminum extrusion is the handguard and upper receiver). I spoke with Ken (the owner of the shop that builds them) via email, and he said that there may be some adjustment required to get it to cycle reliably wih a shorter barrel, though the gas block is fully adjustable.

I don't want an SBR, as I want to be able to remove my can and allow others to use the rifle. If my dad or anyone else at the deer lease is in a particularly cramped box stand while I am in a field, I want to be able to trade guns without running afoul of the NFA. That said, the folks at the LGS mentioned that welding and pinning the muzzle brake/bilock mount onto a cut down barrel will still be a normal rifle so long as the length remains over 26". That would make it more compact with the can attached, while leaving it very short if I loan it to someone.

I see several potential downsides, and wanted to solicit advice:

1.) I heard wrong at the LGS and would be violating the NFA if I tried this method of shortening the rifle. Extremely bad.

2.) Welding and pinning the muzzle brake ruins the barrel and turns it into a 50 yard gun. Very bad.

3.) The muzzle brake, being very close to the user's front hand, shoots hot gas onto your hand if you shoot it, at best requiring the use of a glove or at worst the use of a can (effectively undermining my ability to loan it to other hunters/shooters). Situationally bad.

4.) The muzzle brake wears rapidly and becomes useless, forcing me to get another barrel. Though I wish K&M all the best, small firearms companies go under all the time, and there may be no one to buy a new barrel from when I need it, leaving me with an unsuppressable gun which I must dress up as Michael Jackson (one glove) to shoot. Given the caliber and barrel length, likely an imagined problem.


jason812
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Re: Pinned and Welded Muzzle Device

Postby jason812 » Fri Oct 13, 2017 10:10 am

MaduroBU wrote:I see several potential downsides, and wanted to solicit advice:

1.) I heard wrong at the LGS and would be violating the NFA if I tried this method of shortening the rifle. Extremely bad.

2.) Welding and pinning the muzzle brake ruins the barrel and turns it into a 50 yard gun. Very bad.

3.) The muzzle brake, being very close to the user's front hand, shoots hot gas onto your hand if you shoot it, at best requiring the use of a glove or at worst the use of a can (effectively undermining my ability to loan it to other hunters/shooters). Situationally bad.

4.) The muzzle brake wears rapidly and becomes useless, forcing me to get another barrel. Though I wish K&M all the best, small firearms companies go under all the time, and there may be no one to buy a new barrel from when I need it, leaving me with an unsuppressable gun which I must dress up as Michael Jackson (one glove) to shoot. Given the caliber and barrel length, likely an imagined problem.


1. I could be wrong but if the barrel is off the rifle and cut down and the brake pinned in place before it is reattached, no problem.

2. If cut down properly, it shouldn't affect your accuracy and with a .300 blackout, you will not lose much velocity. The pin should be TIG welded and it's is just a small bead. A heat stop paste or similar product could be used if it's a perceived issue of too much heat going into the barrel but it should really be very localized to the top of the pin.

3. Are the ports angled back to the shooter or at 90 deg? Even at an angle, I would think you would have to have your hand close to the brake for this to be a problem.

4. If you are using the same brake as on your .300 WSM, it will hold up to a Blackout. The .300 Blackout will have it's powder burnt in 8-9" and if you shoot the same amount of rounds through each rifle, I bet the WSM with a longer barrel would damage the brake before the Blackout.

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spectre
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Re: Pinned and Welded Muzzle Device

Postby spectre » Sat Oct 14, 2017 4:56 pm

If you pin and weld the muzzle device, it counts toward the barrel length because it's a permanent part of the barrel. A muzzle device that can be screwed off/on doesn't count toward barrel length. This is a common enough way to attach a standard A2 flash hider to go an inch or so shorter without NFA trouble, and I never heard of a professional (or competent amateur) pin-and-weld that damaged the barrel.
When plunder becomes a way of life for a group of men in a society,
over the course of time they create for themselves a legal system that authorizes it
and a moral code that glorifies it. - Frédéric Bastiat


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MaduroBU
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Re: Pinned and Welded Muzzle Device

Postby MaduroBU » Tue Oct 24, 2017 1:07 pm

Thanks for replies. I contacted Gemtech and they echoed the answers here with the caveat that they will void the warranty on any of their cans used with a pinned/welded mount that they didn't affix themselves. They said that runs about $250-$300 plus the cost of the mount ($100).

I'll post pics and loads when this is all done if anyone is interested as it seems like it will be a perfect little gun for hunting deer or hogs from a box stand or in brush.

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The Annoyed Man
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Re: Pinned and Welded Muzzle Device

Postby The Annoyed Man » Tue Oct 24, 2017 1:42 pm

I don’t know if this will help or not, but I bought my first can - a AAC 762-SDN-6 - because it was originally designed for a .300 Blk with a 9’ or 10” barrel. I built my SBR with a 10.5” barrel from Ranier Arms. Instead of their muzzle-brake, I used AAC’s 51T 3-prong flashhider, which seems to mount the can quite securely. The can has a ratchet that catches the teeth on the flashhider., So whether you’re going to go with an SBR or a carbine or longer length of barrel, that system works pretty well - especially with subsonics. I’ve used that can on .308 and 5.56 weapons, but it really shines on subsonic .300 Blk.

Just something to think about.
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