I had a chance to do some expansion testing with the Hornaday 140gr. GMX Mono bullets today at low velocity. The results were just what I was hoping for, but really didn't expect. I was fire forming some standard 30-30 reduced handloads in my 30-30AI. Through the chrono I was getting just over 1,700fps. My test media was three, two liter soda jugs filled with water backed up with a box stuffed with newspaper as a bullet trap. As you can see from the pictures, at 1,700fps I still got totally acceptable expansion. Judging from the way the jugs exploded, I feel pretty good that the expansion started in the first one. At a starting velocity of 2,300fps with full power loads, this expansion will get me beyond 200yds which is plenty for me. I have found my Mono bullet for my 30-30AI.
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Those look pretty nice!

Those opened up nicely. I see they have a 139 in 7mm, hmmmm.

[b][/b]Excellent!

@S4S4U-Hornady says say the design different bullets for different minimum velocities. These are a for 30-30 and thus a bit slower then most.

I need to try this bullet in my 30-30 AI pistol with Lever Evolution Powder. I wonder how low of a velocity they will expand at?

I have never loaded any Lever Evolution powder in my 30-30AI, it seems pretty slow on the burn rate chart. With the length of the 140 gr. GMX 30-30 bullet, I would be surprised if you could get enough powder in the case to get any where near top velocity. I would be interested in seeing if others have tried it.
I bet this bullet would expand enough at 1,600fps to be fine on game, but I haven't loaded them down that far to test it.

What is the part number for these bullets? I didn't know Hornady made the GMX style in 140 grain, other than the Monoflex.

The part # is 30310. It is the Monoflex. I incorrectly called it the GMX. Same concept. Sorry guys.

Cool! Your test results show this one is worth considering. Thanks for the info.