how can i tell the difference between a 380 barrel and a 9mm

[Haris1]

Hello All: I recently purchased a M11 with a few uppers that once belonged to the late Merle Bitokofer. There is one upper
that I am afraid to shoot a 9mm in because i am afraid if its a 380 barrel that it might be an out of battery detonation.
How can i determine the chambering.
Thanks for your answers

 

[Gaffshot]

Try the plunk test. Drop a 9mm round into the chamber. If it's a 9mm barrel it should go all the way into the chamber and make a hollow plunk sound. If it's a 380 barrel then the bullet will lodge into the throat and shouldn't fit into the chamber all the way.

 

[Haris1]

thanks a lot

 

[theduke]

pic of bolt

There was a thread about these rare uppers a couple weeks back.

 

[CoffeeFreak]

This is the AR-15/M16 forum not the Mac forum lol. You should be able to put a 9MM case and a .380 fired case in the chamber and tell in two seconds just by how deep it goes head spaced and how it looks if you have any experience at all with the calibers. A 380 case might not even extract.

 

[Slowmo]

A 9mm case is ~2mm longer than a .380 case and has a larger diameter around the web region of the case. A 9mm round should not fit fully into a .380 chamber.

 

[corti948]

First off, congrats on acquiring a piece of history! Merle Bitokofer was a legend in the NFA community, and owning one of his guns is pretty cool.

Now, onto your question. The easiest way to determine the chambering is to use a caliber gauge. You can find 9mm and .380 caliber gauges online or at some gun stores. To use a caliber gauge, just remove the barrel from the upper, then insert the gauge into the chamber. If it's a 9mm barrel, the 9mm gauge should fit snugly, while the .380 gauge won't fit. If it's a .380 barrel, the .380 gauge will fit, and the 9mm gauge won't.

If you don't have access to caliber gauges, you can also try dropping a 9mm round into the chamber. If it drops in easily and seats properly, it's likely a 9mm barrel. If it doesn't fit or doesn't seat properly, it's probably a .380 barrel. Just be careful when doing this.

 

[Haris1]

Thanks to all
it dropped in and seated properly and then i shot it
Its a 9 !!