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Posted: 9/17/2009 8:14:54 AM EST
Is it possible to enlarge the gas port on a standard length .308 Armalite AR-10 enough to reliabliy cycle a 1000fps 170 grain round? I was told by one of the vendors who sell adjustable gas blocks that this modification cannot be successfully made.

Thanks
njaxx
Link Posted: 9/17/2009 9:26:43 AM EST
Not worth the trouble. Get a 300 whisper upper if you want to shoot subsonics.

Even if you maxed out the gas port, and relocated it to the pistol position, the big obstacle is the mass of the 308 sized bolt carrier group. If you went crazy with like an titanium carrier, then MAYBE. But once again, not worth the trouble.

Link Posted: 9/17/2009 1:47:36 PM EST
[Last Edit: 9/18/2009 2:48:03 AM EST by pegleggreg]
I drilled out the gas port on my 16" AR10 & put a switchable gas block on it. The gas length is considered Armalite's AR10 Carbine mid length, which is about 0.20" longer than a normal AR15 mid-length gas system, so it is pretty long for subsonics.

I emptied the buffer & installed a Wolff reduced power buffer spring & it would almost cycle, but the BCG would stop over the mag, just before closing.

I had the older-style bolt carrier with the flat bottom. Their newest one is beveled/sharpened it so it will slide over the cartridges in the mag with less resistance. I ordered the newest generation & it cycled. I think I may have trimmed the buffer spring until it would cycle.

I ordered the 4-5 different subsonic .308 loads that Midway sells & they all worked fine. The extreme shock was Much louder than everything else for some reason.

I never shot it for groups or handloaded anything for it ..... too many other projects I guess. The 7.62x39, or .300 Whisper are much more practical & don't have as big of a problem with having too much case capacity.
Link Posted: 9/18/2009 7:14:28 PM EST
Thanks to you folks for the excellent information. It sounds like a whisper .338 or .300 upper might be the best route. I will have to check and see if the suppressor can handle a .338.
Link Posted: 9/19/2009 5:37:51 AM EST
Originally Posted By rabar:
Thanks to you folks for the excellent information. It sounds like a whisper .338 or .300 upper might be the best route. I will have to check and see if the suppressor can handle a .338.


People shooting the 338 spectre usually are using 9mm suppressors. YHM 9mm XL looks good.
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