I've recently come across some .303 British brass, and the interwebs reveals that I can use them to make brass .410's with them. I have found some instructions which call for either HERCO or Red Dot. I was wondering if either of the powders I have on hand, AA#7 and Win 296, would be decent substitutes.

Consulting the burn rate chart in Lee 2nd ed. I find that:
Red Dot is a 9
HERCO is a 19
AA#7 is a 20
Win 296 is a 26

The list is 1-67 where 1 is fast

It would appear to me that AA#7 would be the better choice, but I don't know how to calculate how much of it to use. Would they determine the recipe by weight or by volume?

The AA#7 is close to the HERCO in burn rate, but bulk hay be a consideration. If this case AA#7 is nearly twice as dense.

Any information is greatly appreciated!

I have used ten grains of AA #5 behind COW and a piece of paper towel to fire form rifle cases. I see no reason why you couldn't use a couple of grains more of #7, try them and see what you get. If results aren't what you are looking for, add a couple of grains and try again.

You aren't going to blow up a rifle shooting cream of wheat. There simply isn't enough pressure to do that.

That's awesome, thanks Doubless, again. I think my Thunder 5 should be up to the task since I can switch the chamber from .45/ .410 to .45-70.

I wonder if I could get away with doing this in my back yard ...

quote:

I wonder if I could get away with doing this in my back yard ...

If you live in town, no. But I have done it in a garage inside the city limits with no objections from anyone.