Hornady 5.56mm 55gr GMX

[WS6]

I suspect that this new Hornady 5.56mm 55gr GMX would be a good barrier-blind choice.

http://www.hornady.com/store/5.56-NA...Superformance/


http://www.cheaperthandirt.com/72020-1.html

I'm guessing that it would act similarly to the 50gr load from BH.

I've had very good luck with the new GMX in other calibers so I may give this load a look.

Anyone tried this new load?

Something to keep in mind with Hornady Superformance ammunition being used in a defensive firearm where reliability is a MUST above all else.

http://www.hornady.com/ammunition/su...rated-firearms

[vicious_cb]

Something to keep in mind with Hornady Superformance ammunition being used in a defensive firearm where reliability is a MUST above all else.

http://www.hornady.com/ammunition/su...rated-firearms

Another reason why I no longer buy Hornady. Produce a new 5.56 load and make it non compatible with shorter gas systems, I wonder if they know how much of the AR-15 market consists of carbines vs rifles.

Not to mention z-max and not producing 5.56 TAP T2 for the unwashed masses.

[Watrdawg]

The link definitely was an eye opener. I was hopeing the GMX round might be a less expensive option but now I am having different thoughts.

[5pins]

I guess it would depend on the variety of guns it was tested on. If that variety of guns included rifles that were gassed for .223 pressures then it would not be surprising to have functioning problems. I would like to see the superformance port pressure compared to 5.56.

[bp7178]

Any all copper bullet is going to be very expensive.

[DRT]

Interestingly, I just got my 2012 Hornady LE & Military catalog and they've included the 55gr GMX loading in their catalog. Here are the specifics:


Product # = 81255 (5.56mm pressure)
55gr GMX (no polymer tip that's typical with other GMX bullets. It resembles a non-boattail TSX but with a larger internal HP cavity)
B.C. = .245
S.D. = .157
Advertised Velocity out of a 16" test barrel):
Mz = 3130, 100yd = 2739, 200yd = 2380, 300yd = 2049

Gel Test:

16" 1:9 weapon
Measured Velocity = 3193
21" Penetration (pretty amazing for a fully-expanded 55gr .22 cal bullet)
Max Cav = 4" (not nearly as dramatic as the 75gr TAP)
Depth to Max Cav = 5"
Entry = 1"
Retained weight = 55gr

The bullet looked like a perfect mushroom. I suspect that the guilding metal construction will retain its petals through intermediate barriers better than a pure copper design . The profile of the mushroom looks more similar to a conventional bullet versus the TSX that has substantial gap between the petals. I bet this would make a good hunting round as well.

By the way, the gel shot with the 75gr 5.56mm TAp 8126N still looked the most impressive of any .223/5.56mm round. It obviously remains a top pick for unobstructed shots.

[urbankaos04]

Interesting. I hope the performance of this load does turn out to be similar to the Black Hills 50 gr 5.56 TSX loads. I also hope it doesn't suffer from the poor accuracy of the Super Performance 75 gr OTM noted in testing by Molon (I believe) over on ARF some time ago.

Yes, MOLON did do the testing and found via his testing, which is very thorough, that the Super Performance was not as accurate as other loads. Plus, it appears that this stuff is meant to be used with RIFLE length gas systems. The information is readily available over at TOS. I shot this stuff myself (10 shot groups at 100 yds) which produced a 3.203" and 2.314" groups when using my upper with a 16" nitrided Rock Creek 1x8 5R barrel.

[kenndapp]

if i am not mistaken, i think the 55gr gmx is loaded into the 223 tap fpd line as well. has there been any testing on this load yet? i have conducted various google searches with no avail.

[GRWolverineFan]

One thing that is very interesting about the GMX to me is that it does not have petals like the TSX so it may perform differently through glass (not shedding petals). The one issue I have seen with it vs. the TSX is needing a higher impact velocity to expand.

[DRT]

I've found that at extremely high velocity >3300fps into H20, the GMX's solid, back half of the bullet will poke through the "expanded umbrella", front half of the bullet thus yielding two separate pieces. This phenomenon was seen with a 165gr GMX out of my 300 magnum. The muzzle velocity of my current handloads is ~3290fps and holds together even under these extreme conditions. I believe that the petals on a TSX would shear off at a much lower velocity, probably <3000fps. I've seen 3 of 4 petals shear off of a 70gr TSX 5.56mm when similarly shot into H20 at 2930fps (20" barrel).

Hornady's 5.56mm 55gr GMX load in their LE catalog has a different p/n than the superformance 55gr GMX though advertised ballistic performance is the same. I bet they are the same load but just use different packaging. I assume that they approve it for a short gas system since that's the test barrel that they used. I'll probably send them an email for clarification.

They also offer a .223 version per their catalog.