Flash Hider Question


AK Gun Man 88
April 26, 2012, 04:19 AM
I just bought a .338 Spectre Barrel for my AR15. Originally I was going to SBR and Suppress it but I just bought a four wheeler, so those funds are now gone. The threads on it right now are 5/8-24. I now want to just put a A2 Flash Hider. Only problem is the biggest caliber A2 FH is .30. I talked to the company and they said plenty of guys have taken a .30 FH and drilled it out.

My question is do I need to get as close .338 inches (for the inner diameter of FH) as possible or can I go with a hole that is slightly oversized (3/8 drill bit = .375 inches)?

Thanks, and I know this probably a dumb question.

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April 26, 2012, 08:36 AM
For the most effect, you usually want to go .018 over the bore dia. That means you would want to be real close to .356 when you bore it.
A "T" drill bit is .358 so you should be good with that. Be carefull though when you drill it and make sure its straight. The best thing to do is chuck the brake up in a lathe, indicate it in and bore it out so your sure it is bored straight.

April 26, 2012, 11:14 AM
I totally agree with dsink.
Maintain concentricity however you do the job.
I would try a lathe collet first and INDICATE the internal threads on the flash hider.
Four or five thousadths runout might be acceptable IF you BORE and not drill
the Compensator.

April 27, 2012, 07:13 AM
For a flash hider you don't need to be too close to bore diameter, .375 will be fine. For a muzzle brake or compensator you need to be close to bore diameter so that gasses are not escaping past the baffle.

I'll second the suggestion to use a lathe.

AK Gun Man 88
April 28, 2012, 01:49 PM
Thanks guys. Unfortunately I do not have access to a lathe. I have a drill press with laser guide...I'll take a look and see if I can line it up correctly.

April 28, 2012, 02:33 PM
You might find out the flash hider is harder then your drill bit too.

The good ones are heat treated & harder then woodpecker lips.


April 28, 2012, 02:47 PM
cant use an a2 flash hider... they are threaded 1/2 x 28. ak-47 flash hiders are 5/8 x 24

AK Gun Man 88
April 28, 2012, 10:37 PM
Thanks RC...I'll give it a try and see what happens. One question RC, would I run into any problems using a .458 SOCOM A2 FH (if I can get one) that was threaded correctly on the .338 barrel?

sniper762...check this link


April 29, 2012, 12:42 AM
DPMS makes an A2 with 5/8-24 Threads. I just bought one last week. Midway had them in stock.

As for lining it up properly to open the hole....

Since there is already a hole there, a good drill bit will follow the existing whole. It should not "walk" on you as long as you are drilling/working on a press with a square/flat base.
If you clamp it in a vice and go after it with the hand drill, you run the risk of walking it and 'egging" the hole.

Hope this helps.

April 29, 2012, 11:21 AM
yep thats for the ar10a2....thats different from the ar15a2 that i thought you were speaking of.

AK Gun Man 88
April 29, 2012, 02:07 PM
Mine is an ar15 chambered in .338 spectre with 5/8-24 threads...the reason the above flash hider is listed for the AR10 is the hole is .30 cal and 5/8-24 is usually the typical thread for AR10. The whole thread was about enlarging the diameter to accomodate the larger .338 bullet.

April 30, 2012, 09:07 AM
isnt the 338 a magnum? i didnt think that round would fit wthin the ar15's mag well.

AK Gun Man 88
April 30, 2012, 09:19 AM
338 Win Mag is a magnum. 338 Spectre is based off 10 mm magnum pistol cartridge. It was designed to fit in ar15. Check out the youtube videos on it...pretty slick. Check out teppo jutsu website for more info on the 338 Spectre.

April 30, 2012, 10:30 AM
smith enterprises makes a 5/8x24.have them open it up to your bullet diameter

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