So I got a few boxes of Barnes 647 Tac-X HP's.  What is the best powder to push them with?  In stock I have virgin WC867, Reloader50 and US869.  Is the winner Hodgdon H50BMG for lighter bullets?  I've tried Reloader50 with API's and the group was 5 inches @100yds so I'm thinking that powder is best for heavier bullets?  Old Man??

Ben loaded some up for me. I'm not sure what powder he used and I haven't been able to shoot them yet.

If using a 650 grain projectile and using H50BMG, I've loaded up to 245.0 grains of powder. It is a completely safe loading in my AR-50. If you have another type of 50BMG rifle, you should start at a much lower powder charge and work it up.

When loading South African Ball projectiles that weigh 690 grains, we stopped at 230.0 grains while using Virgin H5010 (OLD batch). If using the newer version of this same powder, reduce all charges by a minimum of 10% as it burns much hotter than original. Most of newer batch has been recalled by Hodgdon Powder Company. Although I have not tried H50BMG with SA Ball, I believe it would or could be an accurate loading. Start at 220 grains and work your loads up properly.

Most shooters of Ball projectiles use WC-860 or versions there of. Some shooters who have acquired the cheaper versions such as WC-872 should realize this powder has extreme temperature variation. It should be delegated to heavier projectiles in 800+ grain weight range.

Alliant Reloder 50 and V.V. 20N29 should be used with 800+ grain projectiles. V.V. 20N29 powder is extremely expensive at $284 for an eight pound jug and as such saved for shooting at extreme ranges. Reloder 50 costs about one-half as much but demand will be driving up the price, as it is an accurate powder as used by many top FCSA shooters. Some of us use oddball methods to heat the loaded rounds while using 20N29 to minimize velocity variations from round to round as chamber temperatures rise during extended shooting strings.

I personally have not used US-869 as some of out FCSA Members have reported it to be extremely temperature sensitive.

YMMV.

You're not kidding about pressure issues with that powder.  I have the 867 but apparently there is little difference between that and 872.  Primers started to get flat corners at 215 along with a sticky bolt.  I backed off to 212 and use that charge for all my 650ish loadings.  Even that low charge gets me in the low 2,700's MV.

Thanks Oldman...very helpful.

You're Welcome.

I am not classified as Master Ballistian but I've played with many powders and projectiles. Some ideas worked, some did not, But I learned lots thru the process.

One test I did resulted in being able to push an 800 grain projectile at 3185 fps average of 10 shots. Doing this REQUIRED a special procedure in itself. I was using coated projectile technology with the bore of barrel also coated. I can not release any other specs as it would result in possible injury if procedure is not followed exactly. Just saying that, I ran out of powder capacity in the 50BMG case and quit testing after reaching scary amounts of new powder choice.

Have FUN, Be SAFE.