Anyone here do any testing of this round yet??


                  70gr GMX


Wondering if there have been any comparisons to other 70 - 77gr rounds (70gr TMK,  70gr TSX,  75gr TAP T2,  77gr MK262 Mod-1 or the like).

Any info on velocity, terminal effectiveness-penetration results (gel testing), barrier (auto glass) effectiveness, accuracy, etc.?  
Been looking but haven't seen a lot of info (comparison or otherwise) posted on it yet.  Any info is appreciated.

Thoughts on how effective this may be from a SBR (10" to 11.5") close in and at say 200-300 yards out?

Tag for info. Need a good 68-77 grain to stock up on for 10.5-20" use. The pricing for good rounds is high. $1 or more per round.

It was just released from Hornday this month. No testing on it from Dr. Roberts or Molon that I can find. It should function like the brown tip ammo with a GMX bullet rather than a TSX bullet.

Is the GMX better than Barnes TSX? Less copper fouling? Penetration? Accuracy?

While not the BH version... the bullet doesn't know who assembled it into a loaded round...

 Molons testing....

http://www.m4carbine.net/showthread.php?174112-Range-Report-Hornady-5-56mm-70-Grain-GMX-TAP-Barrier

HornadyLE catalog.....

http://www.hornadyle.com/catalog/view-catalog

More barriers...

http://www.hornadyle.com/products/rifle-ammunition/556-nato/70-gr-gmx-tap-barrier

Ford v. Chevy..... same goals, slightly different approach's.....IMHO, ( And I am not a professional ballistican.. )  I do feel the GMX is a tougher, less likely to shed its petals bullet.... but with that comes a expansion limitation.....  in order to achieve one goal... you have to compromise on another performance feature.

2383 out of a 10.4

Pretty impressive.

OUCH! 2383 FPS is not very good at all for a 5.56MM pressure 70GR. homogenous bullet load from a 10" barrel. To put it into perspective: The Ted Nugent/Pierce 70GR. TSX load made 2376 FPS from a 10.0" M4 and that is a mild, .223 pressure load. I was expecting around 2500 FPS from a 10" firing either 5.56MM 70GR. GMX load. Hopefully, the BHA load will prove to be faster than the Hornady in short 10"  barrels. If the 2383 FPS MV proves correct for both 5.56MM 70GR. GMX loads, it will have a very negative effect on the range at which the 70GR. GMX will expand when fired from a 10" barrel.  Firm data on MV with both loads fired from 10.0" to 10.5" barrels would be very helpful.

Edit: I am looking for a replacement for the old SSA 5.56MM 70GR. TSX load which made 2575 FPS from a 10.0" M4 with M4 can at 90F/300FT. MSL/29.92". It would expand out to right at 300yds. The M4 can adds approx. 30 FPS to any given load. The new SSA 5.56MM 70GR. TSX load is much, much slower yielding only 2205 FPS over the chrono from the same 10.0" M4 with M4 can at 70F/300FT. MSL/29.92". To keep it fair since it was a little cooler, I again chrono'd the old SSA load & it yielded 2537 FPS. 2537-2205= 332 FPS difference with both cartridges fired in the same weapon within a minute of each other.

I'm used to neutered SSA.

Neutered is a very accurate description. SSA degraded their 5.56MM 70GR. TSX load from a very desirable, wide application SD/HD/hunting load to a virtual TSX target load of very dubious value for my purposes. We definitely need to take a good look at both of these 70GR. GMX loads as well as the new Barnes 5.56MM 70GR. TSX load as possible replacements. If all else fails, the original SSA 5.56MM 70GR. TSX load's very high MV can be duplicated but only by handloading all the way up to MAX 5.56MM NATO pressure of 62,350 PSI with a high energy double based spherical propellant such as TAC or AA2520. The big problem with loading all the way up to MAX 5.56MM NATO pressure with a spherical propellant is that there is just no margin for error such as thermal variation due to warm outside air temperatures or heat-soaking your handload in a warm barrel. So I would much rather buy suitable factory ammo than spend my limited range time on load development. Some of the new factory ammunition types have features not normally available to handloaders: very high velocity with lower pressure by using non-canister grade propellants, new mil-spec brass with staked/sealed primers, crimped/sealed bullets, increased thermal stability, etc. SSA stated that their original 5.56MM 70GR. TSX load only developed 55,700 PSI so it didn't cause me any over-pressure problems even in the summer heat. I ordered another case of the original SSA 5.56MM 70GR. TSX load but received the neutered load instead. U.S. mil-spec 5.56MM loads are limited to 58,700 PSI.

Edit: I have a 10 day hunt/shoot coming up next week but the only new 5.56MM 70GR. homogenous ammo I could get shipped in time was the Barnes 5.56MM 70GR. TSX load. Will take a quick look at MV/accuracy of that load as well as the Barnes 5.56MM 62GR. TSX load in a 10" & 300BLK 110GR. TAC-TX load from a 9" then.

I'm a huge fan of the TSX/TTSX.  Out of curiosity I ordered a box of the BH 70gr GMX for a helo hunt on Oct 28th.  l'll report back with the terminal performance.

P

Awesome, please do, lots of pics while you are at it.

 

I am in MS on a hunt/shoot now but could not get any 5.56MM 70GR. GMX ammo delivered in time to test. So I emailed Carl at BHA for information on their new 5.56MM 70GR. GMX load. They took the time to get numbers on several barrels for us. HTH

BHA 5.56MM 70GR. GMX Chrono Numbers From Carl at BHA:

"Here’s what they came up with:

LMT 10”……........ 2,466 fps
M4A1 14.5”…….. 2 ,687 fps
LMT 16”………..... 2,741 fps
Rock River 18”....2,850 fps
USMC 20”……….. 2,870 fps"

I have some legit "browntip".
It ran 285X, and 290X the two shots I fired through my 16.1" DDM4 at the range on some other guy's chrono. A friend of mine ran Black Hills 70gr GMX 5.56 over a chrono, and got mid 2800's from a 16.1" gun, as well. While this is two different guns, on two different days, and I would never tout this test as "scientific", it does make me think that the Black Hills 70gr GMX is legit 5.56 stuff!

The BC of the Browntip is .314. The BC of the GMX round is .35.

The hole in the nose of the GMX is roughly 2x as far across as that of the Browntip.

The GMX is made of gilding metal, browntip is copper.

I have an acquaintance who has shot both the 70gr TSX and the 55gr GMX into gel from a 7.5" gun.

The TSX mpacted at 2285 fps, and deformation was negligible (the very tip fractured a small piece off the lip, no expansion was initiated).
The GMX round impacted at 2343fps, and expanded flawlessly to a diameter of 0.407"
*Note that the 55gr GMX has the same diameter nose cavity as the 70gr GMX.

All of this with a grain of salt, but I think the GMX's might actually perform better at distance than the TSX's due to the larger surface area of the cavity in the nose, and non-scientific gel-testing which seems to indicate such, as well as a notably better BC.

OP,
    We still don't have a lot of credible info on either the BHA or Hornady 5.56MM 70GR. GMX load. TSX is a different matter as I have fired several thousand 0.224" TSX/TTSX bullets in accuracy/expansion testing & hunting, mostly in short 10.0"/10.3"/10.5" barrels. Hornady indicates that the GMX will expand to 1.5X diameter and shooters are reporting it will do better than that. The standard 0.224" TSX/TTSX bullet have all expanded to well over 2X diameter measuring 0.48" to 0.49" in water shot testing. And the only TSX bullet I have had that did not expand went thru a 4" oak tree before keyholing into the spine of a whitetail buck chasing does. We know the minimum impact velocity for expansion in water-shot testing is 1800 FPS for the 70GR. TSX and 1900 FPS for all the other standard 0.224" TSX/TTSX bullets. Jeff Hoffman, co-owner of BHA, stated that the proprietary 50GR. TSX bullet made for the BHA 5.56MM "auto-glass" LEO load needs 2300 FPS to expand. What I am hearing on the 70GR. Hornady GMX is that it needs somewhere in the neighborhood of 2000 to 2200 FPS to expand but I am not expecting to see the GMX expand to the degree that the TSX/TTSX does. 0.407" is good expansion but it is far shy of the normal level of 0.224" TSX/TTSX bullet expansion.  We need to see more actual testing on GMX water-shot expansion, specifically minimum impact velocity for expansion and the degree of expansion. Timing is bad for me now because I am preparing to go chase whitetail for the season. But I already have the Hornady 5.56MM 70GR. GMX TAP load and will soon have the BHA 5.56MM 70GR. GMX load. After the hunting season winds down in February, I will test them both side-by-side for MV/accuracy/expansion. HTH

I shot some of this ammo into water. 16" barrel, 15 yards or so to targets. It fragmented and tumbled. I have never had any of the TSX rounds do that. They all tracked true and typically kept their petals. I have heard from a friend of mine who has now shot 3 animals with it (hogs/deer), that it expands and tracks true in game, but I believe he used a 10.5" gun. I dunno. You can see below in my photo how the round on the left tumbled and the force bent the petals BACKWARDS after it expanded, and the round on the right is missing even more petals, and has the typical banana shape that comes of a round tumbling.



Both projectiles stopped in/on jug 4, although the first one tumbled out of jug 3, striking jug 4, and ending up on the ground.


Here is how other rounds I have tested with the same weapon/distance/waterjugs have fared:

That is nothing close to what I expected from the 70GR. GMX. For reference: The 70GR. TSX bullets below were fired into water. I have never recover a 70GR. TSX from a whitetail because they have always exited. But "P" has handfuls of recovered TSX bullets from hogs and they appear much the same as the water-shots.

100% weight retention is the normal for all 0.224" TSX/TTSX bullets I have expansion tested even when fired from a 24" barrel into water from 10FT away:

like I said, a friend of mine says it's G2G on game, but I also think he's using a 10.5" gun, and he didn't shoot them at 15 yards. I was personally very dissapointed with the 70gr 5.56 GMX based on water testing, and won't be buying more. I'm probably going to go with the new 75gr Gold Dot, or RA556B, as I know the RA556B is terminally G2G, and shoots 2 MOA 10-shot groups from my CHF .gov barreled carbine just fine. The 75gr Gold Dot, I am getting in in a day or two to test.

The 62 gr TSX did not loose its petals for me in 5 gallon home depot buckets filled with water.

But the Tipped TSX "tumbled" and sheared off petals when it turned 180 degrees.

TSX fired from 16 inch 1-9 twist at about 2970 fps and TTSX from 1-8 at 3020 fps.  I was surprised.  

It is common for the heavier TSX to pitch and yaw and loose petals in medium and large bores., like 300 win mag, 375 h and h, or .458 - 450 Dakota.

I ususally drop down one bullet weight to keep them from turning over and shearing off petals.  It works with 450 grain 458 and 250 grain 375, anyway.  the 500 grain 458 and 300 grain 375 deffinately shear off petals.

I think you are seeing same phenomenon with the 70 grain monometals.  I was just surprised to see it in the 62 grain Tipped TSX.

70gr TSX tracked true for me.

12 ga,

You were using a 1:7 werent you?

I was 1-9 and 1-8.  I think the TTSX and 70 grain probably need a 1-7 to keep straight ahead in game even if they do OK accuracy wise in 1-8.  

Yes, 1/7 all the way around.

Below is one of my first water-shot expansion tests with a 5.56MM 70GR. TSX load. The TSX at the far right was fired from a 24" 1x9. It overpenetrated 24" of water @100yds. then buried itself in the backstop. I had to dig it out with a trenching tool. It tracked straight as evidenced by the entrance/exit holes in the water containers. The severe abrasion of the bullet was due to the hard rocky soil of the backstop. I have water-shot expansion tested many dozens of 55GR. thru 70GR. 0.224" TSX/TTSX bullets in 1x7/1x7.7/1x9 twist 10" thru 24" barrels and none have ever lost a petal.

L-R 70GR. TSX: Unfired/10" Colt 1x7/10" Colt/10"Colt@100yds./24" 1x9 @100yds.