GMX Performance at ~2500fps?

adriel

adriel

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Maybe it's just this particular bullet or bullet+cartridge+distance, but I got so-so on-game results with 130 grain GMX's in 270 Win. Superformance ammo. Good accuracy, great speed, disappointing blood trail and damage on deer and coyote at ~300 yards. Their website claims the bullet should be ticking along at 2573 fps by then, which should be within the performance envelope, but I got small entry and mediocre exit wounds. I'm thinking that it's getting too low on the speed side of things to work well.

All shots were fatal, but I think I might go back to cup & core or bonded for better damage and faster kills.

Can anyone else comment on on-game GMX performance with lower velocity impacts?
 
So you haven't recovered one? I'm not sure how big of an exit hole you expect from a .270...with 2x expansion you are looking at a hole just over 1/2". With virtually 100% weight retention you aren't getting a big shrapnel field you would with a cup and core but at 300 yards you should be getting full expansion.. I've used them in a variety of cartridges down to impact velocities of 1900fps with results and consistent 2x expansion you'd expect from a mono metal. At 300 yards I'd expect you are getting at least this type of performance
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I'd take any listed velocities from the manufacturer with a hefty serving of salt. Unless you are using a rifle similar to their test rifle it could be wildly different.
 
kman300 said:
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7mm 139gr gmx 2650fps or so impact iirc. Broke multiple bones so no reason it shouldn't have opened more.
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One of the things that often happens with bone hits is that the bullet will tumble or veer off course slightly, compromising expansion regardless of the bullet. I've seen virtually unexpanded mono metals that remained in an animal. Only explanation is a tumble or lack of velocity.

Here's the identical bullet to yours after a 350 yard hit on an axis deer.
DSC_0004_zpsd85a8ecf.jpg
 
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I'm used to seeing more damage applied to heart & lungs on broadside shots with cup & core shrapnel, but the GMX could have been completely within operating parameters. The animals still died, just wasn't confidence inspiring.
 
sheephunter said:
One of the things that often happens with bone hits is that the bullet will tumble or veer off course slightly, compromising expansion regardless of the bullet. I've seen virtually unexpanded mono metals that remained in an animal. Only explanation is a tumble or lack of velocity.

Here's the identical bullet to yours after a 350 yard hit on an axis deer.
DSC_0004_zpsd85a8ecf.jpg
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Thats true. Last week I shot 4 point mule dear with 139gr GMX out of my 7-08 Ruger. Shot was at 125-140yds uphill 30deg or so. Bullet broke front shoulder bone 2" or so over the elbow, broke the rib tumbling (oval entrance hole in ribcage) cut plumbing on top of the hart, sliced liver in half and landed just under the skin on the other side. That bulet still weights 136gr (plastic tip missing) has no expansion beside small (2-3mm) bend in the tip when tip was expelled. "Elkhuntr" visited me couple of days ago and was as suprised as I was. Thats the first one recovered to date exept 50gr Barnes X bullet (22K-Hornet) recovered from mule deer neck years ago but that's another story. Those GMX bullets are as good as any other, as a matter of fact, last year I drilled mule deer lenghtwise with the same bullet and the same rifle with frontal chest shot and even after breacking pelvis bone on the way out it still exited.
 
Ya you certainly can't judge a bullet on how it performed in one animal...lots of variables. Shooting them in gel can be a real eye opener as well. Mono metals aren't for everyone but I know I'm sure a convert for most applications.
 
So you like them, great!
Have you noticed any big difference in dropping an animal with them compared to the cup and core jobs you used to use , SH?
I have a scat load of .277 bullets but have wanted to try out the GMX bullets for a while and was wondering what they would be like out of my 26" Ruger 270.:)
Looks like they would be fine, for sure!
Cat
 
Not really cat.....a good hit seems to be a good hit. I'd give them the nod where lots of bone is encountered or lots of penetration is needed but on a broadside deer....I haven't noticed any difference.
 
Would be interested in seeing a photo of the Projectile that tumbled after the leg bone hit , 3 posts above!?
Im not a fan of mono Metals but I've not had any experience using or loading for, So my opinion is just that.
Although I do enjoy SH an hes knowledge on the issues an do read into what he says quite a bit.

anyway
cheers
WL
 
adriel said:
I'm used to seeing more damage applied to heart & lungs on broadside shots with cup & core shrapnel, but the GMX could have been completely within operating parameters. The animals still died, just wasn't confidence inspiring.
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That's mono-metal for you. If you want fast kills on broadside shots, save your money and buy inexpensive cup-and-core 130's from most any manufacturer and push them hard.
 
Northman999 said:
That's mono-metal for you. If you want fast kills on broadside shots, save your money and buy inexpensive cup-and-core 130's from most any manufacturer and push them hard.
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I'm not sure that kills could be classified as faster with a cup and core......depending on shot placement of course. I'd say both bullets kill with equal speed, shot placement being equal. I've seen dozens of animals drop on the spot with both mono metals and cup and cores and I've seen many animals run off and die elsewhere with both. No doubt the damage done by a cup and core if often more dramatic looking but I'm not convinced that equates to faster death.
 
I saw a dall ram shot at 300 yds this summer with a TTSX. One tiny hole in through the lungs and the same size out. My concern is that if you make a bad shot, through the guts, will the animal get away and die where you can"t find it. I shot a big whitetail buck this year and it was pretty much a gut shot but only went about 100 yds with a partition. I had loaded up some copper bullets but just couldn't bring myself to use them in the thick woods where I was hunting and I'm glad I didn't. We will all be using the copper ones some day when regulations require lead free like California.
 
Why would you expect a big hole coming out from a projectile that's going to be about 1/2" in diameter? It's what a bullet does inside an animal that counts...not the size of the hole in the hide. I wouldn't count on any bullet in a gut shot situation. I really don't understand the concern with the exit hole size.
 
sheephunter said:
Why would you expect a big hole coming out from a projectile that's going to be about 1/2" in diameter? It's what a bullet does inside an animal that counts...not the size of the hole in the hide. I wouldn't count on any bullet in a gut shot situation. I really don't understand the concern with the exit hole size.
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Sheep
I think a lot of fellas think that a larger exit hole equates to easier tracking on wounded game, ya know more blood on the ground. FS
 
Fassteel said:
Sheep
I think a lot of fellas think that a larger exit hole equates to easier tracking on wounded game, ya know more blood on the ground. FS
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There is never a guarantee of a large exit hole regardless of bullet. With more explosive bullets you often don't even get one and occasionally you get one the size of your head with a mono metal. My point is, a lot of people seem to believe that a small exit hole indicates poor expansion when the truth is, regardless of bullet, you rarely get more than 2x expansion so a 1" exit hole shouldn't be that surprising, especially from a bullet that retains most of it's weight. The only way you get a large exit hole is from the hide being pushed out by the bullet and tearing, not from the huge shrapnel field of a cup and core. That tearing is more a function of angle, what's being pushed in front of the bullet and speed. The tear on the far side in the hide is little indication of what happened inside the animal.
 
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