Headspace on 9mm AR

[Jcon268]

Just finished building a 9mm AR and was curious before taking it to a range what the recommendation is for checking headspace would be? I've heard some guys say that it's not a big deal, yada yada.

Anything I need to be absolutely aware of? Thanks for any help.

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[kmk1012]

Was this a kit from the same manufacturer or pieced together from misc manufacturers?

 

[Jcon268]

Was this a kit from the same manufacturer or pieced together from misc manufacturers?

A few manufacturers comprise the majority of the build...however, the bolt and the barrel were not from the same manufacturer - I have since taken it out for a test run and concluded the headspacing is good. There are some other tweaks needing to be made but everything is mostly good!

 

[ConcernedCitizen]

About the only way to check headspace is the "plunk" test. Drop a round into the chamber by hand, and you should be able to hear the case mouth hit the end of the chamber. The rim of the cartridge should be sticking out, but not much more than that.

Next, turn the barrel upside down and the cartridge should just fall right out. If it sticks in the chamber, you might have a short throat and the bullet is getting lodged in the rifling.

The "plunk" test is mainly used for checking COAL and crimp when reloading, but it's the only way I know to check.

 

[Jcon268]

About the only way to check headspace is the "plunk" test. Drop a round into the chamber by hand, and you should be able to hear the case mouth hit the end of the chamber. The rim of the cartridge should be sticking out, but not much more than that.

Next, turn the barrel upside down and the cartridge should just fall right out. If it sticks in the chamber, you might have a short throat and the bujtc
llet is getting lodged in the rifling.

The "plunk" test is mainly used for checking COAL and crimp when reloading, but it's the only way I know to check.

I did check this out prior to firing it. And it looked exactly how you described.