Looking around the handguard industry, I'm seeing 12-inch handguards are sort of a standard category.
And by 12", I mean from the front of the receiver face to the end of the handguard. There is actually a lot of variation in how these manufacturers calculate their sizes.
My goal here is to spec a 6.5 Grendel SBR barrel where the muzzle thread shoulder starts just beyond where a 12" handguard ends, so that none of the muzzle device is inconveniently under the handguard.
This will give us the very shortest 65G SBR barrel that still works with commonly available 12" handguards, provided the handguards are calculated in a common sense manner from the front of the receiver face, or top rail, to the end of the handguard rail.
Going from parts drawings (and confirmed by actual measurements), AR receiver barrel threads extend 0.441" from the receiver face. Add to that the thickness of the barrel extension collar or flange of 0.131. Totals 0.572. A 12" handguard less 0.572 is 11.428. This is what the measurement on a barrel needs to be from the barrel's barrel extension shoulder to the muzzle thread shoulder.
Muzzle thread section measures 0.625 and barrel extension thread section measures 0.620. Add to these the 11.428 and you get 12.673. Let's round up and call it 12.7".
Three questions:
1) Is 12" a common size you guys want to use with SBRs?
2) Are my analysis and measurements correct?
3) Anybody interested in 6.5 Grendel Faxon 12.7" SBR barrels specifically dimensioned to mate with common 12" handguards?
And by 12", I mean from the front of the receiver face to the end of the handguard. There is actually a lot of variation in how these manufacturers calculate their sizes.
My goal here is to spec a 6.5 Grendel SBR barrel where the muzzle thread shoulder starts just beyond where a 12" handguard ends, so that none of the muzzle device is inconveniently under the handguard.
This will give us the very shortest 65G SBR barrel that still works with commonly available 12" handguards, provided the handguards are calculated in a common sense manner from the front of the receiver face, or top rail, to the end of the handguard rail.
Going from parts drawings (and confirmed by actual measurements), AR receiver barrel threads extend 0.441" from the receiver face. Add to that the thickness of the barrel extension collar or flange of 0.131. Totals 0.572. A 12" handguard less 0.572 is 11.428. This is what the measurement on a barrel needs to be from the barrel's barrel extension shoulder to the muzzle thread shoulder.
Muzzle thread section measures 0.625 and barrel extension thread section measures 0.620. Add to these the 11.428 and you get 12.673. Let's round up and call it 12.7".
Three questions:
1) Is 12" a common size you guys want to use with SBRs?
2) Are my analysis and measurements correct?
3) Anybody interested in 6.5 Grendel Faxon 12.7" SBR barrels specifically dimensioned to mate with common 12" handguards?
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