Range Report: 90 gr GMX & 257 AI

efw

Handloader
Jan 17, 2011
617
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I picked up 100 90 gr GMXs from MidwayUSA's recently blem sale just to try 'em out in my 257 AI. I haven't fired monometals in this rifle because it hasn't ever cared much for bullets longer than the 100 gr Speer HP and that is why I didn't even bother trying the 100 gr ETips I have on hand for my 257 Weatherby Mag. I'd heard that these GMXs were a bit more "finicky" and would likely require more "tweaking" than Barnes, but here are my results from 2 range sessions; group sizes are edge-to-edge:


P1420109.jpg

First range session running RS-Hunter: 51 (.86"), 52 (.66"), & 52.5 (1.04") gr (load data provided by Johan Loubser @ Ramshot and were safe in my rifle but may not be in yours)

and then these were from today w/ IMR-4350:

P1420110.jpg


Going diagonally across the page from lower left to upper right, 48gr (1.322"), 49 gr (called the 1st shot as pulled, didn't bother recording group size) and 50 gr (1.172"). Lower right is a repeat of 52.5 gr (high) and 51.5 gr (.98").

IMR-4350 has always performed very nicely in this rifle, but I had to experiment w/ Hunter due to its stellar performance both accuracy- & velocity-wise in my 6mm-250. I'm REALLY looking forward to seeing what the Hunter is doing over a chrono! I think my load is going to be 52 gr.

As I said, these loads were safe (no signs whatsoever of excessive pressure) in my rifle, but you'll want to work your way up in yours.

On the COAL, I was pretty thoroughly unscientific in my method, seating them down to the last relief grove.

If anyone has looked askance at the GMX due to the lack-luster performance of the Interbond, you might want to reconsider. I'm glad I did!
 
Those look pretty good. I've had reasonable success with the GMX so far. My results on other cartridges are gratifying.
 
efw,

Looks like you are there, nicely done.

JD338
 
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