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9/22/2017 12:11:25 AM
Posted: 12/22/2005 6:35:05 AM EDT
If this has been brought up before then I apologize. But I would like to hear from anyone who owns and/or has built a 6.8 AR on what the barrel thread pitch was, who made the barrel, and what you used for a flash hider. From what I understand the common thread pitch is supposed to be 5/8x24 TPI. The vortex flash hider made for 6.8 SPC rifles is threaded for this as well. But I just receieved my barrel from Model 1 sales and its threaded for 1/2x36 TPI, which is what RRA and Colt use on their 9mm rifles. I'm just curious as to who else has run into a similar situation.
Link Posted: 12/23/2005 5:15:54 AM EDT
Did I ask this in the wrong place?
Link Posted: 12/23/2005 7:25:02 AM EDT
Igot my 6.8 barrel from Randall rausch of ar15barrels.com, & it's threaded 5/8-24, and I'm going to be using a .30 cal Vortex along with a .30 cal suppressor when I have it put together.

5/8-24 seemed pretty standard for 6.8, except for Barret's. Don't know why yours would be different.
Link Posted: 12/23/2005 8:57:05 AM EDT
My barrel is Made by E.R. Shaw. I don't know why they made it that way. Smith Enterprises lists a 6.8 Vortex with 5/8-24. Part # 1068V. I have contacted them to see if they can help me out. Or see if the 9mm one would work if it would even be any different.
Link Posted: 12/27/2005 6:19:17 AM EDT
Link Posted: 12/28/2005 7:33:01 PM EDT
Link Posted: 1/3/2006 9:20:52 AM EDT

Originally Posted By Randall_Rausch:

Model 1 specified a 1/2-36 thread for simple compatibility with 9mm birdcage flash hiders.
That's what probably came installed on your barrel right?

No, I got the barrel only, no flash hider, no delta ring, lock nut or anything .

I just talked to someone at Smith and it sounds like they have had a few inquires about the 1/2-36 threads. He took the words right out of my mouth before I could even tell him the thread pitch. I brought up the 9mm issue an he noted that they varied a little bit from the other models. I think it has to do with the shoulder dimensions or thread length, i'm not exactly positive. But either way it sounds like they will make some 6.8 flash hiders in 1/2-36.

He asked who made the barrel (for reference I assume) and I just told him it was made for M1S by E.R. Shaw. He also mentioned that a few AR builders seem to be comming up with their own threads instead of using more standard or common ones. I would imagine it would become very frustrating after a while.
Link Posted: 1/12/2006 11:04:59 AM EDT
however most barrel makers make the 5/8-24 threads too short for the standard 308 vortex, the back of the vortex must be modified. I personally like the 5/8 thread size on the 6.8, although I have seen 1/2-28 threaded barrels in 6.8, it looks flimsy without a muzzle devise.
Link Posted: 1/12/2006 11:13:03 AM EDT
[Last Edit: 1/12/2006 11:15:19 AM EDT by Randall_Rausch]
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