1/2" supressor threads on a .308 AR?

J

jk2paintworx

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I am getting ready to build a Lightweight AR10 and gonna be putting a 16" GVT profile Ballistic Advantage barrel on it. I have a Sico Harvester with a 1/2-28 adapter that I use on all of my .223, 22-250 rifles and want to be able to use it on the .308. I know that I can get a supressor adapter with 5/8" but then I would have to switch the adapter when I go back and forth (often). I would rather get a 18" barrel and have it cut down and threaded 1/2-28 but not sure that's enough material on a larger caliber. I don't wanna have to buy a new supressor to do this.
 
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Originally Posted By: Catdog1Personally i wouldnt do 1/2" on a .308

Me either. The math is super simple. Don't even need a calculator. Pitch diameter is .477 on 1/2-28. Less .308 groove diameter only leaves .084. That's ignoring any undercut. But at that spot it would be .457 and leave only .074 walls.

I wouldn't go there. Just me though.

- DAA
 
just get the other tailcap and do it the right way. my can is like that and only takes a few moments to switch the tailcaps from 1/2x28-5/8x24. if you want easier swapping, go to a QD setup.


even if it were safe and left enough meat on the barrel, i dont think most smith would cut it anyway. too much risk of someone unknowingly (or unintentionally) screwing the wrong muzzle device on and big problems ensure.

dont matter if its a can, or a flash hider, or what. 1/2x28 stuff is usually bored out for small diamater bullets... not 30 caliber.
 
Originally Posted By: jk2paintworx... I would rather get a 18" barrel and have it cut down and threaded 1/2-28 but not sure that's enough material (for 308)..
It is, I have a 308 A-bolt cut down by a gunsmith to 18" with 1/2-28, plenty material.
You take on the liability for someone putting the wrong thing on the end, however. That's why its not recommended.
 
Threading 30 cal barrels with 1/2 threads is done often on AK rifles and pistol. It can be done. I would stay away from adapters. To much risk of a baffle strike do to things not being concentric. I tried what you are thinking of doing on an AK. Things were not concentric enough,even with using an over bore.338 can that I would of had a baffle strike. If you are going to try it, make sure you get a suppressor alignment rod to make sure the bullet path is centered before ever firing a round.
 

Standard thread for 308 is 5/8x24. There are plenty of suppressor brands out there that use Quick Detach flash hider/muzzle break adaptors that allow you to use one suppressor on different calibers as long as the bullet dimension is EQUAL TO OR SMALLER THAN THE SUPPRESSOR CALIBER. The only caveat is that you should not run any suppressor on a rimfire rifle unless you can disassemble the unit and clean the baffles.

I use a YHM Phantom 7.62 QD Titanium and I have run this suppressor on 7.62, .223, 6.8 SPC, 6.5 Grendel, 6.5 Creedmoor and 300 BLK.

You will get some blast leakage and therefore less effective sound suppression when running smaller calibers but for hunting it's negligible. The main goal IMO is just to make it hearing safe and more enjoyable when out in the field. In reality a few decibels of sound difference is not going to matter to you or whatever you are hunting. I certainly don't feel the need to spend $1k per rifle for a caliber specific suppressor.

I can see a guy spending the money for a thread on unit for a specific rifle when trying to set up a long range rig for accuracy but that does not apply to my hunting style.

You stated that you use an adaptor and you did not specify the caliber of your unit. You might just be able just order an adaptor for the 308 build with 5/8x24 threads if your suppressor is a 30 caliber unit.

 
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Supressor is a harvester .30.
I use it on 2 .223 ARs a 22-250 tikka and soon to be a 6.5Gredndel or .308 AR. My adapter in my Harvester is 1/2-28 so I can just spin it off of one rifle onto another. I like this convienience and I have the adapter in the supressor torqued down tight enough so that it doesn't end up staying on the barrel when I spin it off. So if I have to get another adapter in5/8-24 for the supressor I will be switching that when I switch rifles. Not the end of the world but I do it a lot when I go to the range.
 
So in the end, it would be nice to have my Grenel or .308 threaded the same as my other rifles. Nothing will ever be threaded on it besides a .30 harvester and a thread protector.
 
It is less than 1 minute to switch the end cap on that Harvester. I do it all the time. It is not worth the risk to save that small amount of time.
 
As a machinist who threads barrels quite regularly, I wouldn't undertake this project for one reason; THERMAL EXPANSION.

Not only will you run the risk of concentric irregularities under high heat usage, but your chances of permanently locking two dissimilar metals together will increase exponentially.

Not worth my reputation If I weld a guy's $300 barrel to his $1000 can.

Buy the CORRECT $99 adapter and sleep better doing so.....
 
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