Underwood ammo

henkech · Jan 18, 2014

I was testing a 50 round box of the Underwood 9mm +P+ 115 gr in my CZ P-01. One round did not chamber properly, and was lodged in the receiver. This is an unusual occurrence, it never happened before in this gun. I did some research, and measured the overall length of several brands. To my surprise the underwood rounds were considerably shorter than the other brands. Perhaps the shorter rounds combined with the hollow point bullet are prone to catching on something. And also, maybe the way that underwood is getting that 1400 fps speed, is by putting the bullet farther into the casing. See table below. The underwood round is almost 2mm shorter than the speer gold dot (these are using the exact same bullet).

length in mm of various 9mm rounds

speer gold dot 28.57
underwood (speer gold dot bullet) 26.75
freedom munitions (ball ammo) 29.25
speer blazer (ball ammo) 29.20
snap cap 28.40

thanks, Chris
Portland OR

Certaindeaf · Jan 18, 2014

All things the same, it's true that shorter oal will/does increase pressure.. but so does +1/10gr powder.. and powder is cheap. I hear you though.. having a round not being able to chamber is not a good thing. Some people say to do the "thunk test" for autos or load and spin your cylinders for revolvers with your fightin ammo.
Barring all whatnots, I've heard nothing but good things regarding Underwood.

Mikej · Jan 19, 2014

I don't recognize those numbers, the dot's in the wrong place??? Well, I'm not going to get into my conversion table and translate! I don't know where my conversion table is.....

I load a bunch of 9mm with Montana Gold hollow points, and load them at 1.085 so they will chamber in Wifey's Kimber. Maybe it's that particular style of hollow point? According to the recipes I'm loading low-medium velocities. The shorter OAL doesn't seem to make a difference in any of our other 9mm guns, guns that WILL chamber a 1.125 OAL. Perhaps using such a hot round, (1400fps is pretty HOT), you're pushing the limits of your recoil spring?

Mike

henkech · Jan 19, 2014

dear Mikej, like it says in the post, the length is in millimeters. 25 millimeters to the inch, so your inch lengths are right in the same ballpark as my mm. conversion is easy, just multiply or divide by (25.4). thanks for the idea about the recoil spring though. As I'm selecting a Defense Ammo, I'm trying to get as much info as possible. thanks Chris