So I have this uzi barrel and a 9mm round.......

[biggunzz]

When I stick the round into the barrel it wiggles just a little bit. Is this normal to have a very small amount of play with a new barrel?

 

[UZI SBR AWC]

Yes.

 

[Shadow]

New barrel

The round will be smaller than the chamber. When you fire the round the brass will expand to seal the chamber which is the reason that when reloading you resize the brass down to its original diameter. In the past I have seen head space gauges for sale but I don't know if there are equivalent gauges for diameter. Having said this I have never worried about it. If you were to shoot new brass and it expanded to the point of splitting the case then I would be concerned. Brass that has been re-sized many time will split if not anealed but it is because it work hardens. I have sized brass 14 times or more before it split and then I just throw it away. The act of firing and expanding then sizing down work hardens the brass which makes it susceptible to splitting and anealing softens it. TMI huh?

 

[tony k]

This one was pretty loose in the chamber but it still fired ... of course, it's a 9mm round and the chamber it was fired in was a 1911 .45ACP. Didn't hurt the gun a bit, but the accuracy was terrible.

 

[jim c 351]

When I stick the round into the barrel it wiggles just a little bit. Is this normal to have a very small amount of play with a new barrel?

I asume the barrel you have is a SMG barrel.
All of the open bolt SMG's that I have use sloppier chambers than a pistol chamber. The combination of a fixed firing pin, atight chamber, and a oversize cartridge, could result in a discharge before the bolt is closed.
Jim C

 

[bullyforyou]

This one was pretty loose in the chamber but it still fired ... of course, it's a 9mm round and the chamber it was fired in was a 1911 .45ACP. Didn't hurt the gun a bit, but the accuracy was terrible.

HA! at my last CQB pistol class, a guy managed to run THREE rounds of 9mm through his shiny new P220 combat before it jammed up. :brick i couldn't even believe the mag would hold the 9mm rounds, let alone the gun chambering and firing them! he hit every popper too. sounded weird though.