As a machinist I can’t get past the quality of hardware store drills to bother looking at the sizes they carry.
But this job isn’t actually hard to do with a cheap drill, just make sure it’s not dull or you will push a burr into the bore.
As a machinist I can’t get past the quality of hardware store drills to bother looking at the sizes they carry.
But this job isn’t actually hard to do with a cheap drill, just make sure it’s not dull or you will push a burr into the bore.
HD has pretty hard Cobalt and titanium bits that will definitely cut barrel steel. Regardless, for me the standard fractional increments are too big and dont let me land on most precise gas as possible.
From 5/64; 0.0781in to 3/32; 0.0937in is 19.9% increase
0.0156 ÷ 0.0781 = 0.1997
From 3/32; 0.0937in to 7/64;0.1093in is 16.6 % increase
0.0156 ÷ 0.0937 = 0.1664
The ANSI Drill bit size increases in increments of 2-3%. My target size per Adams Arms is 0.0980, which from the Faxon barrel starting with a 0.078 port, this is a jump of 25% increase in gas. Going with the 7/64 bit would add another 12% extra gas
bit# in % increase
3/32 0.0937
41 0.0960 2%
40 0.0980 2%
39 0.0995 2%
38 0.1015 2%
37 0.1040 2%
36 0.1065 2%
7/64 0.1093 3%
The gas drive increase is proportional to the area or the diameter ratio squared.
If it's mostly working now, you only want to go up one or two drill bit sizes, testing each time.
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
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