# Underwood 10mm 180grTMJ report



## RDub

Underwood 10mm 180gr TMJ



I found the C.O.L. to be 1.245"

Taking a look inside I found 9.6gr of propellant that looks very much like 800-X.



A closer look;



The bullet weighed in at 179.4. This looks just like a Speer 180gr TMJ.



At the range I shot two groups this time. One, with the stock spring, and the other with an ISMI 22# spring and SS guide.
Gun is a brand new Glock 20-SF with stock (4.6") barrel.



First, I was surprised to see such a significant velocity spread in both groups. I had velocities as low as 1155fps and as high as 1275fps. Now If I was to try to use any kind of powder measure with 800-X, I know what would happen.. Large weight variations.. So I wonder if that is happening here. I am tempted to pull down some more rounds and see what variations there might be.
Well the ISMI spring seemed to help with accuracy a bit, and the brass stayed closer and easier to find.

Second, this ammo is warm. Many of the fired cases produced smileys..



The cases that did not have smileys measured;
.4340, .4392, .4348, .4343, .4341.. These must have been the rounds that shot in the 1100's.

All in all, the ammo shot very well and functioned flawlessly through the Glock 20-SF. I'll keep a magazine full of these for woods carry. I just won't bother looking for brass..


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## Nanuk

Those certainly are hot.


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## berettatoter

The 10x25 is one bad-assed round. I don't own one, but wish I did. Nice pics.


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## cadjak

Any chance of seeing a picture of the base of the bullet Underwood used in this ammo? I shot some plain ol' green box Remington 180gr TMJ and was surprised at how thick the jacket was.
Thanks


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## papahawk

@ berretatoter, you are right. it ias a bad ass round I have 2 of them and going to get the Olympic Arms 10mm upper for my AR-15. My 10mm loads run in the 1400 ft/sec range with Blue dot or 800-x and a 180 gr XTP out of a Gen1 G-20 with no "smiley faces" or other pressure signs. the also run good out of my Kimber Eclipse. *note* both guns have 22# recoil springs


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