Powder suggestions 120 GMX in 6.5x55

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pacobillie

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I got my hands on a few boxes of 120 gr. Hornady GMX bullets (monometal, similar to Barnes TTSX) which I intend to use as my deer hunting bullet in 6.5x55. There is very little published data out there, and most of it is very conservative, as is often the case with 6.5x55 data.

The potentially suitable powders that I have on hand are H4831, A4350, IMR7828 SSC, and RL25. With 143 ELD-x, my rifle did best with IMR 7828 ssc, although I got good results with H4831 and H414. Btw, the 120 GMX is almost the same exact length as the 143 ELD-x. I will be using Lapua brass. Where Would you start? BTW, feel free to run the combination through QL. FYI, COL is 3.11 and I use CCI BR2 primers.
 
From reading, RL22 is supposed to be the cats meow with the 6.5x55. I saw somewhere 120 gr. ttsx/gmx can be pushed to 2800 FPS maybe a little higher. Hopefully someone with experience will chime in here....
 
You're not getting many responses because you don't mention the type of rifle or action you're using.

I shoot a Tikka T3 and it will easily handle loads that are considered to be to hot for the older 96 and Krag actions.

Remingtons, Winchesters, Zastavas and a few others out there are considered to be strong enough for higher pressure loads.

I have a load that is safe in MY TIKKA T3 with the 120 grain bullets you mention.

My load for this bullet, that shot well in my rifle was:

51.5 grains of IMR 4350, CCI 250 primers, 120 grn GMX = 3100fps

There weren't any pressure signs but you may want to start 5 grains lighter and work up.

Most of the powders you list are on the slow side to just to slow for these light bullets and are more suited for heavier 140 grain or heavier bullets. The A4350 would be the exception of the bunch.

Your CCI BR2 primers are plenty hot enough for good, consistent ignition.
 
Range report:

So, I loaded three series of loads with the 120 gr. GMX:

H380, starting at 43 gr. up to 45 gr. in 0.5 gr. Increments. Fed 215M primers. 3.13 COAL
A4350, starting at 45 gr. up to 47 gr. in 0.5 gr. increments. CCI BR2 primers. 3.13COAL
H4831, starting at 47 gr. up to 48.5 gr. in 0.5 gr. increments. CCI BR2 primers. 3.13COAL

With H380, the groups tightened as the charge went up. 45 gr, yielded the tightest group, and lowest SD and ES. 1/2 in. group. 2836 FPS average. No signs of pressure.
AA4350 was a no go!. The very first shot (45 gr.) clocked at 3003 fps, and the bolt was a bit hard to open. I did not shoot the rest. There was a distinct ejector mark on the case head. This is a mystery to me, as the charge was reasonably low.
H4831 shot best at 47.5 gr. Group was a cloverleaf but it may be luck. Avg velocity right at 2800 FPS. Surprisingly, the 47 Gr. and 48 Gr. groups were about 3/4 of an inch.

FYI, the rifle is a 1916 sporterized M96, with a 24 in barrel. It sits in a sporter walnut stock, and the recoil lug has been glass bedded.
 
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