556 Headspace help

[lower lover]

Buddy of mine has a new PSA assembled upper with a factory 556 FN stamped barrel and a fail zero bcg.
The bolt closed on a claymore 223 1.4666 NoGo,
Any thoughts on what's going on?

Thank you

[G-forceJunkie]

Is the barrel .223 or 5.56? II bet it is 5.56...why are you using .223 gauges for 5.56? The 5.56 No-Go gauge is longer.

[lower lover]

Is the barrel .223 or 5.56? II bet it is 5.56...why are you using .223 gauges for 5.56? The 5.56 No-Go gauge is longer.

It is a 556 . I will update the original post what is correct Gage to be using?

[G-forceJunkie]

Use a 5.56 no-go gauge. It is 1.4696" You could cheat and try and put a piece of .003" thick tape (scotch tape or clear packing tape) on the rear of the .223 no-go gauge if that is all you have.

[ar15barrels]

http://ar15barrels.com/data/headspace.pdf

[kendog4570]

All 223 and 556 chamber headspace dimensions, with the exception of machine guns like the SAW or MK46 fall between SAAMI minimum and maximum specs. For most, if not all, cartridges of this type it is .010" from Min to Max.

Industry practice is around .004 to .006 from GO (SAAMI Min) to NO GO for almost all bottleneck rounds in use today. If it doesn't close on a field (SAMMI Max which is GO + .010") you are safe.
Of course we strive for GO for maximum accuracy and brass life, but that is not as big an issue in a gas gun as it is in a bolt rifle. A self loading gun that swallows a field gauge is much safer to shoot than one that fails a GO. Partial and out of battery fires are no fun.
There is more wiggle room than one would think. Maximum ammunition must fit in a minimum chamber, and a Max chamber/Min ammo combination can produce a bit of slop and still be quite safe.

[smoothy8500]

The bolt closed on a claymore 223 1.4666 NoGo,
Any thoughts on what's going on?

We have to ask how did you "check" the chamber? Using only a fully stripped bolt? Or, hit the bolt release and dropped the bcg on the gauge?