Hornady GMX warning

[Shotshill]

Heres a 308gmx at 400yds taken from a hog in NorCal... Hmmmmm

 

[goathunter]

Thx, all! I, too, reached out to Barnes and got the same numbers, but only for a couple bullets, so thx to sndmn11 for the detailed reply. Take away—use Barnes TTSX. No reason at all to use GMX. If you have to talk about switching out of the killzone and going to the shoulder just because your bullet won’t expand at standard velocities in soft tissue, you’re driving with the check engine light on. Not only that, but what happened to the ethos of quick kills?

Switching to Barnes isn't a "magic bullet". It's still a mono and even at recommended velocities needs a well placed shot, in my experience.

 

[aussiehunter]

There’s really not any homework to do. It has a recommended impact velocity on the box as well as estimated velocity’s for the cartridge the buyer is using. Seems pretty cut and dry. Box says 2050 FPS at 300 yards and shows minimal expansion at 2000 so logic says keep shots under 300 yards. Seems hornady makes it pretty easy and clear.

My 270 win 130gr GMX Outfitter is roughly 2050fps at 500 yards as per the box. Thinking of keeping it around 450 yards to get most out of it

 

[Pabst]

Well a 139gr GMX out of my 7mm-08 sure did a number on a whitetail last weekend. Went clean through both shoulders and the deer didn't so much as twitch. Quite a bit of blootshot meat on the shoulder first hit, but the exit side was really clean.

 

[BooneAK]

I don't know when this change happened, but I'm glad it's happened: Hornady has switched out the GMX bullet for the CX bullet, which requires about 400 fps less for the same expansion as the GMX. In my view, and certainly for .308, it's still too high of a minimum velocity (circa 2300); see attached photo -- I wouldn't want any less expansion than that. Their 165 gr .308 load is shooting 2224 FPS at 200 yards, which is pretty short for a lot of us these days (again, the .308 is only a 200 yard rifle? I don't think so.) And they're still not putting all their information in one place -- you have to go to the .pdf catalog, again, to see a picture of mushroomed bullets and corresponding velocities.

I'm not down on Horn, but I was right about GMX. CX is better -- just make sure you're hitting those velocities with your caliber and setup. I don't appreciate the stiff arm I got from CS about a refund when all this sorted with my .308 GMX, but, again, the CX is better than the GMX. Regardless, after GMX, I switched to Barnes TTSX in Supercharged Buffalo Bore -- increased velocity and increased mushrooming, still with weight retention and non-toxic.

 

[tcpip95]

I know we’re discussing terminal velocity for maximum expansion, but is there a corresponding energy number for max expansion as well? Barnes 168 TTSX going 2,240 fps has roughly 1,870 ft/lbs of energy. Everything I’ve read says to keep this bullet above 2,200 fps. Out of my 30-06 that’s a 400 yard shot (which is better than I’m going to shoot). Is there a minimum energy number that can be used as well? I would think that how hard the bullet is impacting the target would be a better measure than just velocity.

 

[Formidilosus]

I know we’re discussing terminal velocity for maximum expansion, but is there a corresponding energy number for max expansion as well? Barnes 168 TTSX going 2,240 fps has roughly 1,870 ft/lbs of energy. Everything I’ve read says to keep this bullet above 2,200 fps. Out of my 30-06 that’s a 400 yard shot (which is better than I’m going to shoot). Is there a minimum energy number that can be used as well? I would think that how hard the bullet is impacting the target would be a better measure than just velocity.

No. Velocity is the determiner of upset/expansion.

 

[35WhelenAI]

Is there a sticky about the bullet energy and how it does not correlate expansion? Would be GREAT have something to refer folks to so it doesn't end up being discussed (again and again) in SO many threads.

 

[Pabst]

I've only used the 139gr .284 version of the GMX, sad to see the BC dropped in the CX iteration. Maybe expansion will be improved but I haven't recovered a GMX yet, only two kills with it so far.

 

[Moserkr]

Found this pic for my .30-06 today. Shooting hornady 180gr gmx outfitters. Ive recovered 1 bullet so far and it expanded great - but at 20’, that deer took every bit of energy it had with a frontal shot. I have a 22” barrel as well so I lose even more velocity. Seeing as my longest kill is 32 yards with a bow, not sure if Ill ever find where this round fails. Trying to up my long range game but I get bored and still hunt a lot. 300 yards is still plenty for me.

 

[Tmac]

I don't know when this change happened, but I'm glad it's happened: Hornady has switched out the GMX bullet for the CX bullet, which requires about 400 fps less for the same expansion as the GMX. In my view, and certainly for .308, it's still too high of a minimum velocity (circa 2300); see attached photo -- I wouldn't want any less expansion than that. Their 165 gr .308 load is shooting 2224 FPS at 200 yards, which is pretty short for a lot of us these days (again, the .308 is only a 200 yard rifle? I don't think so.) And they're still not putting all their information in one place -- you have to go to the .pdf catalog, again, to see a picture of mushroomed bullets and corresponding velocities.

I'm not down on Horn, but I was right about GMX. CX is better -- just make sure you're hitting those velocities with your caliber and setup. I don't appreciate the stiff arm I got from CS about a refund when all this sorted with my .308 GMX, but, again, the CX is better than the GMX. Regardless, after GMX, I switched to Barnes TTSX in Supercharged Buffalo Bore -- increased velocity and increased mushrooming, still with weight retention and non-toxic.

I’ve also seen 2,000 fps bullet expansion pictures in marketing material for the CX. Have not found any definitive minimum velocity figures yet. From what I can gather, the heat shield tip, different groove design and maybe the bullet shape are the main changes. In essence a play for a higher BC to retain more velocity, not so much an effort to offer a design with a lower velocity expansion window. Then they say better long range performance. Technically correct vs a GMX, but likely a difference without a distinction. I could be wrong, but that’s how I see it so far.

I use mono’s quite a bit, all light for caliber with launch speeds of 3k or more. To a max range of 350 so far. Mostly 129 & 130gr .277 and 145gr .284 bullets. Results have been good, due to good placement and velocities. We have been well above the velocity minimums, except for one kill. TTSX and LRX are my choices, with the LRX being preferred. The only exception is two Moose with 180 TTSX’s out of an 06, one at 20 yards and one at 350 yards (the exception).

As far as the CX, I won’t try them unless their minimum velocity rating is close to the LRX’s. Look at a cross section of a TTSX vs a CX, it appears the hollow part is deeper on the Barnes, so my guess is the CX will need more velocity to perform than the TTSX and it won’t be close to the LRX. But that’s just a guess.

 

[SDHNTR]

Wow, I’m really amazed at the extent of over analyzing this. In the real world, there isn’t a hill of beans worth of difference between Barnes TTSX and Hornady GMX. Shoot the one that shoots better out of your gun. I have no idea what my impact velocity is and couldn’t care less about minimum speeds for expansion or whatever else people are obsessing over. Shoot enough gun for the critter you’re after. Find the bullet that shoots best in your gun. Then shoot the animal in the shoulders. Stuff will die. I’ve seen it hundreds of times with all sorts of copper.

 

[S-3 ranch]

There’s really not any homework to do. It has a recommended impact velocity on the box as well as estimated velocity’s for the cartridge the buyer is using. Seems pretty cut and dry. Box says 2050 FPS at 300 yards and shows minimal expansion at 2000 so logic says keep shots under 300 yards. Seems hornady makes it pretty easy and clear.

I know the thread is old , but I been researching mono .308 for a couple of months,
and can’t figure out why the factory loads are loaded extremely slow
90% are 165/168gr @2700fps and max range 300yards listed on the box !!
the sole exception is a 150gr ttsx loaded @2900 and max effective 400yards for elk and deer
the 130ttsx runs out of gas @ 350

why don’t mono loads put some R&D to maximize performance

 

[SDHNTR]

I shoot an 18” bbl .308 at it spits a 168 mono at about 2565-75. I give it zero seconds worth of thought. I just put the crosshairs on the shoulder, touch it off, and get the game bags out.

 

[Weldor]

Agreed, Killied a Bison in 2010 with 165 gr. GMX at 200, lights out right there. 16" AR10.

 

[HighUintas]

Just use hammers if you want to shoot copper. You'll have 1 shot drop right there performance at 1000y with a 308

 

[meta_gabbro]

I know the thread is old , but I been researching mono .308 for a couple of months,
and can’t figure out why the factory loads are loaded extremely slow
90% are 165/168gr @2700fps and max range 300yards listed on the box !!
the sole exception is a 150gr ttsx loaded @2900 and max effective 400yards for elk and deer
the 130ttsx runs out of gas @ 350

why don’t mono loads put some R&D to maximize performance

A significant part of that is case capacity. A 150gr TTSX is the same length as a 180gr boattailed lead bullet, and a 168gr will be similar to a 212gr. If you want to duplicate a pissin hawt 168gr load for something like an SST with a TTSX you simply cant fit the same amount of powder in the case. If you handload you can get velocities up, but it requires compressed loads which is not something that manufacturers like to do. Loads from Barnes (which tend to be on the spicy side already) only get to just north of 2800 with 168's, so it's not unreasonable at all for the factory ammo to be a comfortable bit below that.