Originally Posted by mtnman05
My reloading manuals show a minimum COL of 1.585" with a 180gr.
Okay .44 caliber, COAL 1.585". I'll assume .44Mag but it could also be 44WCF(44-40).
As carver mentioned, figuring...and assumptions...can get dangerous really fast. Help fill in the blanks and we can post up more complete advice.
For starters, unless specifically stated otherwise, that overall length measurement is a MAXIMUM, not a minimum.
You can seat the bullets down to the cannelure with no problem.
A 180grRNFP .44 is a pretty short bullet so you will probably be seating them shorter than the listed COAL. It's a more common weight/profile for 44WCF but I've used a lot of 180gr RNFP lead in 44Special loads...I've never tried it for even starting .44Mag loads though.
As for the powder charge, find some 180gr lead data and stick with it.
Cross-referencing to several manuals (and jacketed data mind you, so it won't corelate 100%) a starting load of 20gr of 2400 will get you into the 1200-1500fps range depending on what barrel length you're firing out of.
Even 1200fps will almost certainly guarantee that you'll have some leading without a gas-check or at the very least some VERY good lube.
Hodgdon's online data center shows several loads for a 185gr lead RNFP. This data will work for your 180gr lead.
They list 1.54" for COAL...but without knowing for sure which brand bullet they used for that data it's still open for a bit questioning.