PDA

View Full Version : 556 barrel chambering with .223 headspace guages?


jfk
02-14-12, 02:50
If someone chambers a barrel with a 556 reamer and uses .223 headspace guages to measure, will the chamber be .223 or 556?
Todd.K
02-14-12, 10:56
The chamber dimensions are determined by the reamer.

If you want to know if your headspace is within M16/M4 acceptance headspace range you will need 5.56 gauges or incremental 223 REM with the length to datum diameter marked (as in 1.4636", not GO)
jfk
02-14-12, 13:03
The chamber dimensions are determined by the reamer.

If you want to know if your headspace is within M16/M4 acceptance headspace range you will need 5.56 gauges or incremental 223 REM with the length to datum diameter marked (as in 1.4636", not GO)

Ok, so if a barrel is chambered with a 556 reamer and a set of go/no go guages were used to check the bolt/barrel extension fit, would it be okay to fire? The bolt rotates fine with a go guage but stops on no go and definitely will not rotate with a field guage.

The reason I ask is because I already have a set of .223 guages and was wondering if a set of .556 guages were neccessary to chamber the barrel to 556 specs.
MistWolf
02-14-12, 13:57
Chamber dimensions are the same. The difference between the 223 and 5.56 are in the leade

http://m4carbine.net/showthread.php?t=55149
Todd.K
02-14-12, 15:53
SAAMI 223 REM headspace is 1.4636" to 1.4736"

M16 5.56 headspace is 1.4646" to 1.4706"