Thread: Slow Powder, Heavy GC boolit, anyone got a ballistics calculator?

Originally Posted by Micky Duck

you could always run the old tart on black smelly stuff............

Thanks @PommyMcPomFace and @shooternz.

He heh, could be tempted just to stuff it with BP and go. Saying that, BP pressure spikes are no joke. And I'd go for the sulfur free stuff.

As I indicated earlier, not looking for super performance, just to shoot them fairly fast/flat up to 2-300m max, while keeping chamber pressures as low as possible. Not just for safety, the SMLE action will handle it, but to minimise "shaving" of boolits when there is shallow rifling. If I load H414 for a target velocity of ~1800 fps I think that would would keep pressures well inside the comfort envelope of the cast lead boolit.

Like @shooternz said, a stick powder would be better as filling the case more. I did actually look for H4350 for this reason but GC only had equivalent H414 in stock. H414 is equivalent by weight but more dense as it's a ball powder, and I got it as it promised the ability to make some hotter but still lower pressure loads. But incomplete case filling can be required --- just like now when I'll probably have to go develop a load around 38grains of H414 which is about 75% of available space, and I may have to get some dacron wool or similar.

Anyway, as I now have H414 and TB, H414 is what I'm using for the supersonics. If H414 won't work accurately then it's back to the TB as the problem will be lack of bullet obturation. This web site suggests that for bullets of BHN 12 you need 17,000 PSI / 1180 BAR for proper obturation, but I think I really just need to get out there and try some loads. The obturation problem may be though why there is a tendency to use slow powders for heavy bullets - the heavier bullet has a bigger inertia and would that mean it obturates better than lighter bullets lower chamber pressures? Just a thought.

I like the software warnings about percentages of unburnt propellant at time of bullet exit. I guess an annoying big number with short barrels.