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Posted: 1/17/2025 4:59:16 PM EDT
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I asked this in the gunsmithing forum but I figured MG would get more eyes on it. Does anyone have blueprints or some good measurements on a Mac 11/9 barrel? I’m considering making one from a blank for a custom project - I know the barrel thread in the trunion is 5/8-18, and can probably extrapolate a lot from there as far as diameters, and I’m sure a lot of other dimensions (in front of the trunion) aren’t super critical to anything and I’ll probably mill in some wrench flats or hex. Mainly I’m just looking for the exact length of the barrel from the back of the chamber to the shoulder. I know the feed ramp is basically a 360 degree chamfer. Not my picture: obviously if I owned a Mac 11/9 barrel and a ruler I would know the length 
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This barrel is in an upper, so I can't give exact measures like you want.... overall length looks a lot like 5 3/8" with a tape measure, but a caliper probe jammed down its boom hole says 5.5" muzzle to bolt. 1've got 1.73" from muzzle to face on retaining clip, and somewhere around 0.18" from face of retaining clip to front of receiver. Front face of receiver to inside end of barrel looks a lot like 3.5", but that's just eyballing a caliper that's floating over the part. the front of the receiver is 0.63" thick, and the barrel from chamber to inside of ... and my hands and sweatpants are now caked in carbon... no more numbers tonight.  ... edit - words are hard when you're asleep |
Disclaimer - OP is bad at knowing things, and might catch on fire.
Vet - Op MMAMA
Every other species kills off their stupid......we cater to them. -- spin-drift
Nobody ever called 911&said I just did something smart. -- TheFlynDutchman
Vet - Op MMAMA
Every other species kills off their stupid......we cater to them. -- spin-drift
Nobody ever called 911&said I just did something smart. -- TheFlynDutchman
Thanks! To clarify, I don’t have any Mac parts to measure off of currently, but I’m going to build a carbon fiber tube upper with a commercial trunnion. I have a 22 barrel blank on the way and I’m going to chamber it in 22TCM9R and profile it to a MAC barrel. That’s all going on a DB alloy 3D printed lower that uses Sten mags, hopefully with a wire style extending brace. 
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That sounds like an interesting project. I look forward to seeing the build. |
Disclaimer - OP is bad at knowing things, and might catch on fire.
Vet - Op MMAMA
Every other species kills off their stupid......we cater to them. -- spin-drift
Nobody ever called 911&said I just did something smart. -- TheFlynDutchman
Vet - Op MMAMA
Every other species kills off their stupid......we cater to them. -- spin-drift
Nobody ever called 911&said I just did something smart. -- TheFlynDutchman
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Originally Posted By KELBEAST: I know the barrel thread in the trunion is 5/8-18… https://i.ibb.co/6w3czv2/IMG-7046.jpg The receiver threads are larger than 5/8”. The Sionic muzzle threads are 3/4”. |
Joined:
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EE: 100% (16)
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Originally Posted By KELBEAST: Even if they’re not on a legacy receiver, I’ll be threading the barrel for a commercially available trunnion. https://i.ibb.co/q5j3Tws/IMG-7244.png https://i.ibb.co/yn2Z9KQ/IMG-7245.png Originally Posted By KELBEAST: Even if they’re not on a legacy receiver, I’ll be threading the barrel for a commercially available trunnion. https://i.ibb.co/q5j3Tws/IMG-7244.png https://i.ibb.co/yn2Z9KQ/IMG-7245.png I didn’t know such a thing existed. I can take some measurements from my uppers and post it. It’ll be close, but not exact. Originally Posted By whiskerz: Go ask over on Snugbus. You’ll end up down a rabbit hole of stories about back in the day without an answer. Good place for nostalgia, not so much for current information. Originally Posted By SecondAmend: People in the MACTalk section of UziTalk.com might be of assistance, also. Best of luck with your project. MHO, YMMV, etc. Maybe you can get it there. Chances are that you will be told to scrap your plans and just get a Lage upper, LOL! |
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