Home Forums Hunting & Shooting Hunting Rifles Hornady GMX and Accuracy

Has anybody had any luck with this bullet.? Last time I tried these I got like a 3" group in my 378 WBY.
As much as interlock bullets usually shoot lights out, these shoot horrible. Anyone??

Wondering the same, got some 80’s for the 6 ai, trade them out on the BT’s so I can hammer bulls.

I have tried the GMX in several weights and calibers and have yet to get acceptable results in the accuracy department

What is up with these slugs? Nothing like the TTSX!

They sure didn't work too well for me. Best I could get were 3 inch groups at 100 in my 8 twist 22-250.

I have tried the 110 grain GMX in my 300 Blackout. My Ruger American in that caliber shoots these into one hole cloverleafs at 100 yards. The 125 grain GMX out of my 308 shows a lot of promise as well. I intend to try them in other calibers.

I have not loaded any components but I have shot a couple bull elk with the 185 Superformance ammo out of my .338 Win Mag. The Superformance ammo was MOA or better for me. The velocity was a little disappointing as the average fps was 3022 from a 22.5 bbl

Wish I can get those groups

I get good groups with 139 7mm GMX handloads using RL 15 out of my 7 08. They aren't as accurate as match bullets, but they sure put down game.

I've not had much luck with GMX bullets either and I've tried them in a number of calibers, both in factory format and in handloads. I've had such poor results that I won't buy any more GMX bullets for reloading and I've even pulled a bunch of 120gr GMX 6.5 CM Superformance factory loads just to get the brass! I've had such good results with Barnes bullets that I'm not interested in trying to find a GMX load that works well. I'll buy Federal Trophy Copper if I need a good factory load that uses a copper bullet.

When I first got a 6.5 CM barrel for my AI AW I shot three 5-shot groups using Hornady's 140gr A-MAX load (12, 3 and 6 o'clock) and then shot a 5-shot group using the 120gr GMX load (9 o'clock). This is a small data set but follow up tests with the GMX stuff didn't get any better so I don't waste barrel life with it. The AI will shoot almost any factory load well, and some exceptionally well, but the GMX is not one of them.

GMX stands for "Gay Max". You have to shoot them out of a 270.

Factory Superformance 80 grain GMX works well out of my 243. About 1" groups, or maybe a little less, off a block of wood. Advertised velocity is 3400 fps, but I didn't clock it.

Good to know - just bought a box of .277 130's to try and then discovered this thread. Sounds like I needn't worry...

Be curious to see....start low, work up...

I have used the SuperPerformance GMX 150 in 30-06, as well as the 150 SST SP, and Remington's 150 Corelokts in my heavy barreled Mauser 98 for the last several years.i. The SST and GMX run 3-shot, inch groups, at 300 yards, the Corelokts just slightly larger. Federal 180s(Powershok??) do the same, tho I don't recall offhand where they print in relation to the above mentioned. It seems this rifle just isn't real picky....... . Probably shoots even NP as well....

At 300 yards the SST loads shoot about 6 inches higher and 4 inches right of the Corelokts, and the GMX about the same from the SSTs.

I have not used the SP loads in any other rifle. I have found no advantage to using GMX vs SST at over 300 yards on caribou. Inside 300 yards, they seem to do a bit less damage than SST, which can create LARGE wounds, especially if hitting bone or large muscle mass. Inside 300 yards, I see no advantage to using either of the SP loads in preference to the Corelokts.

These are all factory loads. I have not hand loaded for this rifle. Pretty sure i can't do better than that for accuracy over the factory fodder! Even if I had better eyesight.....


My experience with Barnes TSX factory loads in .260 and .243 indicates I will probably never buy another box of same in any caliber. Not when those groups are 4 moa and much cheaper Corelokts do moa in those two rifles. Outrageously priced with inferior accuracy just doesn't float my stick.

Might try some TTSX in hand loads when I get back to it. Probably not. All copper bullets (expensive!) just don't excite me much when C&C have proven to do all I require of them with less copper fouling.

The factory Horn. Creedmoor load shots decent, sub MOA 3 shot groups in my Wife's RAP, not anything like an AMax or NP, but works

This is true. My .260 doesn't seem to like anything but 140's. Pretty much any 140.... I can live with that.

One reason it didn't like those Barnes 120 TSX, no doubt.

The only real test is to shoot and see....

The only one I've tried is the 139g .284 in a 7mm Remington Mag. I eventually found a load that would go sub-MOA for 3 shots, although it was much more work to find than the 150g Barnes TTSX. That was the easiest load work up I've ever done with that rifle. 0.5-0.75" 3 shot groups.

The GMX did seem to be a bit sensitive to seating depth. When first testing the bullet, after finding a good charge weight I tried various seating depths. My load work-up was initially done at 3.320", but I decided to test various other seating depths:
3.360" COAL -> 3.079" 3-shot group
3.330" COAL -> 1.306" 3-shot group
3.300" COAL -> 1.234" 3-shot group
3.280" COAL -> 1.318" 3-shot group (don't ask my why this wasn't tested at 3.270", it was 7 years ago. )

And later:
3.290" COAL -> 1.618" 3-shot group (not sure what happened here...)

After switching powders, later testing with more shots showed that the GMX could reliably run 1 MOA to 1.25 MOA. I won't complain about that performance for large game (in this case, Elk).

It's my backup hunting load if for some reason I run-out/misplace the 150g Barnes TTSX.