I'm loading for my first custom chambering a 6.5 Remington Magnum AI.
I have a 30" 1/8 barrel, 139-142 grain bullets primarily and am curious about the slower powders.
I was going to start in the range of IMR 4350 and RE19.
Would the RE25/H1000/Retumbo class be too slow for my capacity and tube?

What's the case capacity?

It should be 72 grains of H2O.
I have been too busty to start fireforming and confirm.

I would not use the 4350 or slower powders unless you wanted reduced velocity loads. Start with 4831, RE22, and 7828 to find high velocity loadings and to utilize that extra case capacity. I have a 6.5 WSM and find those powders do well with many bullets. The slower powders you mention work OK in my cartridge with the heavier bullets, but the 6.5 WSM does have slightly more case capacity (80gr) than a 6.5 Rem Mag AI.

Your case scales out about the same as a 7 Rem Mag, so you'll be using similar powders when using similar SD bullets. This concept is covered here. Checking my Hodgdon listings at that SD for the 7, it appears the H1000 class gives a wee bit better performance than the H4831 speed of powders. Slower than H1000 and you need compressed loads. Running the numbers through QuickLOAD gives the same results, but QL suggests you might have to go to compressed loads at the H1000 speed.

MLC,

I shoot a 6.5-'06. I think you might like MRP and MRP2 in your cartridge.

jim

Thanks gentlemen!
I couldn't have asked for a better set of responses.

quote:

Originally posted by prof242:
I would not use the 4350 or slower powders unless you wanted reduced velocity loads. Start with 4831, RE22, and 7828 to find high velocity loadings and to utilize that extra case capacity. I have a 6.5 WSM and find those powders do well with many bullets. The slower powders you mention work OK in my cartridge with the heavier bullets, but the 6.5 WSM does have slightly more case capacity (80gr) than a 6.5 Rem Mag AI.

Did you mean "or faster powders"? I think 4831 & 7828 are slower than 4350. But I'd agree with your recommendation on these powders for that overbore caliber.

Well I'm finally getting to shoot the rifle.
With the Sierra 142 naked H4831SC was showing the beginnings of pressure with 55.5 grains at 2900 fps.
I'm working with RE22 now and have gone to 58 grains @ 3078av.
There seems to be more left as there is no sign of pressure and prints increasingly better from 56 to 58 grains.
I'm seeing about 50fps per grain of powder increase.
H1000 is next on the list and I have a good feeling about it.

You might want to look at Accurate 3100 or better if you can still get it DP 86. roger

Who makes DP 86?

roger

quote:

Originally posted by MLC:
Who makes DP 86?

It was distributed by Accurate Arms as a surplus or over run. Might just be a little hard to get now, but it is awfully close to Accurate 3100. I use quite a bit of the 86 and It really performs in large capacity cases.

Thanks,
Re22 got me over 3200fps but accuracy was falling off.
So I have a pound of h1000 to start with.
I'll look into both.

If anyone cares IMR 7828 gives some amazing speed in this chambering with the 139 Lapua.
3475 was the maximum load in 80 degree weather.
The downside is that it burns very hot.
I'm going to try MagPro, which I believe that bartsche recommended ages ago.

Again, if anyone cares, I decided to chase accuracy over sheer speed and have used my rifle out to a mile accurately using H-1000 and the 142 Sierra at 3150ish.