Re: Is there a formula for powders slower than listed in the manual??
I've never used a formula per-se, but I have made guesses on loads and tried to be in the safe area for it. As an example, if the gun I have shoots 60gr of 4831 and that's at the upper end but without pressure. Well, 60 of H1000 will be plenty safe, if it fits. Then after seeing 1 round over a chronograph, I move up in charge if I have determined that it isn't causing any trouble. Going slower in burn rate is fine with me. Going faster is NOT fine and can lead to catastrophic failures. Dont go faster on the burn chart without hard data from a RECENT reloading manual for the round you are shooting. If there is no data on a faster powder, theres a VERY GOOD REASON why not. Also, don't go several steps on the burn rate chart at one time. Use only powders you are familiar with and have an idea of what to expect from.
I'd highly doubt that a slower powder will help your 06imp anyhow. H1000 or R25 would be about as slow as I could see working. Slower stuff than that is simply for filling super overbore cases. H870 or WC872 is gonna be way full and won't give any more velocity than 4831sc. Retumbo is gonna be about the same. MRPII is WAY slow/Volume too.
If you have something that you disassemble and reassemble enough times, sooner or later, you'll have two!