XM177 Near Clone Muzzle Break

nissan300ztt · Oct 25, 2022

So the shop I work for is a good place to work. As long as we pay for our own material we are allowed to use any machine to make what we want. I have loved the look of the Armalite XM177 muzzle device for years. I could have purchased one but decided to make my own "clone". This is as close as im willing to get without getting some sort of claim that I bought it. The material is 416 Stainless I dont know what hardness to treat it too. But the Slots were EDM'd as I needed to practice my EDM skills a little more. This is designed to be pinned and welded to an 11.5" barrel to make it legally 16" barrel Length.

Posting for thoughts and criticism.

nissan300ztt · Oct 25, 2022

jmm03 · Oct 26, 2022

interesting project, does it really have to be heat treated if it is not subjected to the bullet? Or does it need hardening because of the heat from the gases? Jim

nissan300ztt · Oct 26, 2022

jmm03 said:
interesting project, does it really have to be heat treated if it is not subjected to the bullet? Or does it need hardening because of the heat from the gases? Jim

thats the thing. I cant find any references for why the heat treatment is either necessary or not. My heat treat oven at work will only get 416 to 44 Rockwell. But there is an issue of scaling. But it doesnt refer to size changes or physical scaling.

FredC · Oct 27, 2022

I have found that 416 machines better heat treated 28 to 36RC. Mostly I purchased it already treated. You will not get it much harder than 44RC even with oil quenching. You will get some scale and distortion. I would not do it now.

I have some annealed 416 BQ (bearing quality) on hand and I pretreat it with oil quenching and I get 50RC plus but this grade is hard to find.

nissan300ztt · Oct 27, 2022

FredC said:
I have found that 416 machines better heat treated 28 to 36RC. Mostly I purchased it already treated. You will not get it much harder than 44RC even with oil quenching. You will get some scale and distortion. I would not do it now.

I have some annealed 416 BQ (bearing quality) on hand and I pretreat it with oil quenching and I get 50RC plus but this grade is hard to find.

Im reading online articles and it seems as though if its just a muzzle device and not exposed to the bullet touching it heat treating isnt really required. So I will test it this weekend without heat treat and see what the result is.

FredC · Oct 27, 2022

Looks nicely finished now, messing up that finish with post heat treating would be a shame.

I have some plain annealed 416 bars that I quench in oil the temper at 300F. Do not have a tester but I guess the short bars are 44 to 46RC. They machine with a bright finish but the tools do not last as long as they with bars furnished in the 26 to 32 range. The BQ full hard bars machine with a definite difficulty but still get a bright finish. Just some info for next time.

nissan300ztt · Oct 27, 2022

FredC said:
Looks nicely finished now, messing up that finish with post heat treating would be a shame.

I have some plain annealed 416 bars that I quench in oil the temper at 300F. Do not have a tester but I guess the short bars are 44 to 46RC. They machine with a bright finish but the tools do not last as long as they with bars furnished in the 26 to 32 range. The BQ full hard bars machine with a definite difficulty but still get a bright finish. Just some info for next time

Yeah I just put it in the glass media blaster. with a stripping grade grit. And I plan on mounting it on a barrel and put the entire barrel and break into the media blaster to get a uniform finish.

50BMG DUDE · Oct 28, 2022

Does not need heat treatment as a muzzle device. most of the aftermarket A2 style AR15 birdcage flash hiders are 12L14 (soft as you can get)

Does need to be blind pinned and welded over to qualify your barrel as 16" (also good rule of thumb is make the BBL 16-1/4" so there is no quibbling over a potential violation.

300sniper · Nov 1, 2022

I'd send it out for black nitride.

nissan300ztt · Nov 20, 2022

50BMG DUDE said:
Does not need heat treatment as a muzzle device. most of the aftermarket A2 style AR15 birdcage flash hiders are 12L14 (soft as you can get)

Does need to be blind pinned and welded over to qualify your barrel as 16" (also good rule of thumb is make the BBL 16-1/4" so there is no quibbling over a potential violation.

Ive decided im just gonna put it on a pistol lower. So the ATF can lick my taint.

TeachMePlease · Dec 1, 2022

nissan300ztt said:
Ive decided im just gonna put it on a pistol lower. So the ATF can lick my taint.

Sorry about your family, Frank.

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