Questions about compensators & barrel thread specs

[cbe1962]

I am new to Grendel and ARs but am building my own. Enjoying the process and appreciate all of the information I have been able to find here.

I just received my Shilen 20" barrel from Midway last evening. Looks great, and I can't wait to get the upper assembled and get to the range. Before I do that, I am considering sending it back to Shilen to have the muzzle threaded. 90% of my shooting will be under 500 yards at paper.

I am not sure I will put a compensator on it, but I think I want the option and know I will be hard pressed to break it down once assembled.

My questions are:

1. If I do decide to send it in for threading, are there advantages to 9/16x24 over 5/8x24 for the Grendel?

2. There seem to be more choices for 5/8x24, but exit holes tend more towards .308. How would a .308 compensator perform on a Grendel?

3. Can anyone direct me to drawings or specs for either or both of those threads? At a minimum, I need to send the desired thread length along with the diameter and pitch to Shilen.

Thanks,

Cam

[LongRanger]

I don't know what Shilen would be willing to do for you but I know that Eabco will cut the threads and install your choice of muzzle brake purchased at their website for a total of $200 or less depending on brake chosen. http://www.eabco.com

[Drifter]

https://www.adcofirearms.com/shopservice...cfm?code=1

[LRRPF52]

If you have a heavy for end on the barrel, the 5/8x24 makes more sense. AA went with 9/16x24 so there is enough of a shoulder on a lighter weight barrel profile to support the crush washer.

[cbe1962]

Thanks, I did call Shilen and they are happy to thread the muzzle for me and are in the same price range as most other gunsmiths I have found. Plus I like the idea of having the original barrel maker do the work. However, they weren't as helpful when it came down to spec'ing the threads.

Thanks LRRPF52,
My engineering training was pushing me larger, but I didn't know about availability of Grendel compensators with those threads. My barrel does have a heavy for end and it helps to understand the original rationale for 9/16x24.

Do you have any idea about the length of threads and the unthreaded section between the shoulder and the threads for 5/8x24? I have found Gemtech and AAC thread drawings on-line, and there are some differences in those areas. Thread length varies from 0.600" to 0.755" apparently depending on application. And the unthreaded section either 0.050" or 0.060" (this probably doesn't matter). I am just looking for a 'standard' spec to give to Shilen so I have options if/when I decide to put on a compensator.

[rasp65]

Cbe You might consider having the brake in hand and send it along with the barrel when the threads are added. I agree with you that having the barrel maker do the job is the way to go. That way if there is a problem with the barrel when you get it assembled they can't come back on you for modifications to the barrel.

[cbe1962]

Thanks Rasp. I will follow up with Shilen.