Superformance GMX, not impressed Update: recovered one

kman300

kman300

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I killed a buck yesterday with the 139gr GMX superformance (against my better judgement I decided to try them). They only chronographed 3070fps vs the claimed 3190fps. They were accurate and a "tough" bullet so I gave them a try. I exploded his heart and impact velocity was ~2800fps. I will never use these again, nor will I recommend the GMX bullet to anyone that asks. I have used the barnes tsx/ttsx (100gr version) and killed deer with impact speeds ~3400fps and I had no where near this much bloodshot and wasted meat.

Entrance
entrance.jpg


Exit
exit.jpg


Draw your own conclusions.
 
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Exploded the heart but there appears to damage to the flesh. Normally a heart of heart/lung shot through and throught the rib area does not create this amount of damage. What I see quite often is "Blood shot" where the blood pools within the tissue.
A friend shot a deer through the shoulders with an 8mm Remington Mag, and I recall the damage looked similar.
 
I shot a doe two weeks back with a 150gr GMX superformance in .308 at 50yards. No problems whatsoever, clean going in, clean going out. Double lung shot

Didn't take pics after I skinned it, but this shows the exit wound.
X9a1zl.jpg
 
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To answer a few questions and comments.

The deer was DRT.

No other bones were hit, ribs going in and ribs going out.

I don't neck shoot deer moving deer at ~130 yards.

Here is a picture of the exploded heart. I've shot holes through hearts before but I've never had one actually explode like this.
heart.jpg


To the fellows saying speed kills and I need to look at bigger boolits, I don't consider an impact speed of ~2800 all that fast to be honest and the GMX isn't supposed to be a "fragile" bullet. And I do use bigger, slower boolits. They make some bloodshot too, just not as much :)

It was a .40 cal 260gr lead bullet. Impact was ~1480fps.
in.jpg


OTOH here are some pictures of a deer I shot last year with a 257 wby. Impact speed was ~3350fps with the 100gr tsx.

wound1.jpg

wound2.jpg
 
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Either too much mess or not enough expansion, it is difficult to find the perfect bullet...and when you find one you like, is it consistent? Lately I have been disappointed in Hornady Interlocks.
 
I found the Nosler ballistic Tip gives a good balance in between Damage/expansion and DRT's. Just lately I used A Matrix Ballistic bullet and was impressed.

Your GMX story reminds me of similar Hornady SST experiences...

I gave some to my uncle of his .270 (150gr.) and calls me this past monday....What the Hell did you load those rounds with !!! Ive never had 3" exit holes before :D
 
Boomer said:
Like they say, speed kills, but it kills messy with a fragile bullet. Maybe you should trade that 7 mm in on a .45/70!!:p But switching to a TSX/TTSX would probably work too.
Click to expand...

GMX is hardly a fragile bullet. I bet if you do a search you could find a thread about them not expanding and penciling through...lol I'd bet there was no fragmentation in this example. Just the result of a mass moving through a deer. You can't judge bullet performance on one experience....there's way too many variables. From the testing in ballistic medium that I've done, I'd say the GMX and the TSX offer pretty similar performance and they should because construction wise they are pretty similar.

To the OP, I doubt you'd have seen anything much different with any bullet...btw, good shooting.
 
Pathfinder said:
I found the Nosler ballistic Tip gives a good balance in between Damage/expansion and DRT's. Just lately I used A Matrix Ballistic bullet and was impressed.

Your GMX story reminds me of similar Hornady SST experiences...

I gave some to my uncle of his .270 (150gr.) and calls me this past monday....What the Hell did you load those rounds with !!! Ive never had 3" exit holes before :D
Click to expand...

It is interesting that you mention the BTips. My buddy killed a buck yesterday with a 280 using 150gr CT btips. I handloaded them for him and they chronographed 2750 fps. He killed the buck at ~70 yards and impact speed was ~2600fps.

I expect bloodshot from btips. I just didn't from the gmx.

bentrance.jpg
 
kman300 said:
It is interesting that you mention the BTips. My buddy killed a buck yesterday with a 280 using 150gr CT btips. I handloaded them for him and they chronographed 2750 fps. He killed the buck at ~70 yards and impact speed was ~2600fps.

I expect bloodshot from btips. I just didn't from the gmx.

bentrance.jpg
Click to expand...

In the case of the BT, I suspect much of the bloodshot can be attributed to fragmentation but I doubt that very much with the GMX. I suspect it weighed the same coming out as it did going in. Whatever the combination of angle, speed and who knows what else, you got a lot of bruising. The next shot you may get none. If you'd have thrown a rock through the deer at the same velocity I suspect you'd have gotten the same result. The beauty of the mono metal bullets is great expansion at high to moderate speeds and nearly 100% weight retention. Sometimes bruising happens. Using a TSX or MRX wouldn't have changed a thing. They perform similar and fragmentation is pretty well non existent, save for a petal occasionally breaking off.
 
I hope to shoot some deer with that same load this weekend.

I'm not too worried about excessive meat loss; deer ribs suck anyway.


Last year, I nearly took a doe's head off with a 140TSX out of my 7mm08 and a neck shot - just a flap of skin holding it on, the neck bones, meat, and arteries were all shredded. And that same 140 TSX at about 2900 fps MV WILL destroy all the meat on a shoulder at 150 yards, also from personal experience.

Personally, I'd prefer that my bullets are unnecessarily destructive, than not destructive enough. I'd prefer sub-optimal shot to ruin some extra meat, than to result in a lost animal.
 
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