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7/7/2017 2:51:51 PM EDT
Anyone know the mil spec angle for the M16 chamber chamfer?
7/7/2017 2:58:49 PM EDT
[#1]
If I remember correctly it is 23 degrees

Just do a google search for 5.56 chamber angle, you will find what you need.

ETA, I just went ahead and did it for you.

Attached File
7/7/2017 4:45:59 PM EDT
[#2]
I think he's looking for the chamfer around the entrance into the chamber, not the case shoulder angle.
7/7/2017 7:04:32 PM EDT
[#3]
Correct the cut that aids feeding into the chamber
7/7/2017 7:51:34 PM EDT
[#4]
Quote History
Quoted:
Correct the cut that aids feeding into the chamber
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Email Tony at Ballistic Advantage and ask him, or the guys at Faxon, they are both members here.
7/7/2017 7:59:53 PM EDT
[#5]
I've always used 59°.
7/7/2017 8:58:20 PM EDT
[#6]
I thought I would have this dimension in my PDF files, or pic files, but I don't.  I thought it would then be a 15 second google search then, too.

I've gotten away with a flat faced barrel with about a 1/16" or less polished radius into the chamber without a failure to feed due to not having this chamfer in several AR barrels.  I've left the barrel entrance at a sharp 90 before and had it dig into cartridge shoulders, but even a slight radius took care of that problem.
7/7/2017 9:12:37 PM EDT
[#7]
Yeah, it doesn't have to be a whole lot.

I've seen some barrels where it's massively over cut, and causes the web of the case to bulge.
7/8/2017 4:24:33 AM EDT
[#8]
Quote History
Quoted:
Yeah, it doesn't have to be a whole lot.

I've seen some barrels where it's massively over cut, and causes the web of the case to bulge.
View Quote
120 degrees total included angle, with a diameter of 0.55 inch.  The radius between the chamfer and chamber is 0.0620 inch
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