Guys,

Bought some NEI 320 gr .377" GC and some NEI 400 gr .417" GC slugs from the Bullshop.

The owner (Dan) suggested some slower, but still hot loads with H4831 in .375 H&H and suggested a starting charge less than that for 400 gr jacketed slugs in .416 Rigby.

Loaded some ... 70.0 gr H4831 in .375 H&H and 95.0 gr H4831 in the Rigby. Went to the range today.

Replaced the scope rings on the CZ 550 Rigby so was trying to find zero at 50 yards. Impact point was all over the place ... no consistency at all. So, after checking the bore for leading ... it was pretty clean ... I located the scope with 350 gr Barnes Xs and it shot a ragged hole. The cast slugs were still all over the place.

Tried the .375 slugs in a .375 H&H Weatherby Mark V. Group was 4" or so at 50 yards. Again, no major leading. Checked the rifle with a 235 gr Speer load that shoots well ... and got the usual one hole group.

Both rifles shot great with jacketed slugs the rest of the day ... water jugs at 200 yards and a Buf mover at 20 yards

Dan's philosophy seems to be that a load at around 2200 fps with the cast slugs won't result in leading and works in his .375 and his .416 Rem Mag. Doesn't seem to work in my guns.

Am looking for loads in the 1600 to 2000 fps range for practice ammo. Accurate Arms does list some in that range using XMR 5744. I looked for some at two shops today, but they did not have it. Will look for it other places next week.

Any other ideas for loads in that range?

thanks,

You state the bore looked pretty clean, but examining the muzzle end closely by using a white patch around 1-2" in the bore might well show leading against the lands. This will ruin accuracy.

Bullet fit. To the throating and groove dia-- how'd that check out?

Did you seat the bullets for land contact at chambering? Could be any one of several DE-tales... chrono-ing the loads for ES's would help.

Dan's suggestion to use slow fuels is sound-- but you have to get them burning with some uniformity too. IMO one trial run with a cast loading and finding failure is about par for the course..

[ 04-20-2003, 14:57: Message edited by: aladin ]

Try some IMR 3031. That's what I use in my .375's with a 270 gr cast bullet. I put a tuft (0.7 gr) of kapox over the powder as my load is about 45 grains.

Since your bullet(s) are heavier perhaps a lighter load should be tried. There is no problem with 3031 in working up a load from very small amounts.

That Hodgdon reduced load powder might be too fast to get up to 2200 fps with such a heavy bullet.

Mike. A load that has worked well for me is the RCBS #37-250-FN cast from an alloy of 10 pounds wheel weights, one pound linotype, a three foot piece of 95/5 lead free solder (5% silver) and a one-third cup of magnum bird shot. Bullets size to .379", lubed with Lyman Magic Orange, and a Hornady gas check. Powder charge is 49.0 gr. of IMR-4895 with a one gr. tuft of dacron. The load will do from 1.25 to 1.5 inches at 100 yards when I do my part. Brass was federal, but it should work in any brand of brass.
Paul B.

Like Paul B., I shoot the RCBS 37-250 in a 375H&H. While I've used 4895 with good results, 50.0 gr IMR4064 works better for me. I ran out of 4064 and substituted the same amount of Varget. No filler in either load. Accuracy & velocity (1975fps) were the same. I think you'd do better with a medium burning powder (4895, 4064, Varget) for the results you're looking for. If you experience hangfire, start adding powder one grain at a time until it goes away.