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Underwood Ammo 9mm +P+ GDJHP Short Barrel Test

5K views 11 replies 9 participants last post by  smolck 
#1 ·
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#3 ·
tnoutdoors9 channel on youtube has a bunch of tests with Underwood ammo. ALL hit the advertised muzzle velocity or exceed it. Too bad my M&P isn't rated for +P+ ammo.
 
#4 ·
Great work. I'm glad you pointed out that you were happy it didn't reach the advertised velocity due to the shorter barrel. At the higher velocity you may have encountered bullet failure (fragmenting, etc.). I like some of the Underwood loads, but I think they may be driving the bullets faster than they were designed to handle.
 
#12 ·
Actually, on the 115gr +P+ Underwood normal 9mm load he got 1434fps average in a Glock 19 and had 9" of penetration and MASSIVE expansion of .88". Not sure if the other loads 124 and 147gr were the same.

EDIT: went back and looked, all of the Underwood 9mm rounds did very well on tnoutdoors9 SIM tests.
 
#9 ·
I would imagine that firing that bullet at 250 fps faster than it's designed for would cause it to expand rapidly, then overexpand, i.e. the petals fold all the way back such that the end diameter is actually slightly smaller than it would be otherwise. This is less of an issue, I think, since the bullet was fully expanded for much of its travel after impact. With a bonded bullet, there's less of a chance of losing bullet petals, but if you push it too far, you might start bullet fragmentation.

I am curious exactly what the pressure of their +P+ loads is... IIRC, the other notable +P+ is the Winchester Ranger-T 127-gr. +P+, which is only supposed to be another 10% or so over +P.
 
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