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Old 01-25-2019, 8:19 AM
bene bene is offline
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Default Armalite Ar-50 50 BMG Barrel

Does anyone have the diameter where the receiver meets the barrel. Also looking for the diameter where the barrel meets the muzzle brake. I am turning a barrel blank to make a .510 DTC. I do not have the Ar-50 receiver as of now.
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Old 01-25-2019, 2:22 PM
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ar15barrels ar15barrels is offline
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Have whoever you are getting the gun from wrap a piece of string or wire around the barrel at your two measurement points and then measure how long the string/wire is with a ruler or tape measure.
That will get you a much more accurate diameter measurement than simply eyeballing with a ruler or tape measure would, but not as accurate as a pair of dial calipers...

Armalite has an exploded drawing showing the barrel out of the reciever in their manual.
The muzzle threads are 1-1/4" diameter so the barrel is likely around 1-3/8" to 1-1/2" at the muzzle and probably 1-3/4" at the breech to have a shoulder behind the 1-1/2" breech threads.
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Last edited by ar15barrels; 01-25-2019 at 2:36 PM..
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Old 01-25-2019, 3:09 PM
bene bene is offline
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Thank you
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Old 01-26-2019, 10:33 PM
50BMGBOB 50BMGBOB is offline
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Actually the factory barrel is a Navy contour, the breach theads are 1 1/2" and the barrel is 1 5/8" forward of the threads. The muzzle brake thread is 1" 14tpi and the barrel is just under 1 1/4" just before the brake. When I replaced mine I went with a heavier barrel, 1.7" at the breech taper down to 1.375" at the muzzle. The receiver is a hexagonal just over 2".
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Old 01-27-2019, 12:01 PM
bene bene is offline
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Thanks for the info.
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