Didn't see 2400 powder in either Alliant.com, Hodgdon.com or in the pertinent issue of HANDLOADER magazine. Don't know why. It's my favorite in .44 and .45's. Be careful. Maybe call Alliant company. Ask an expert.
Given your situation, I would either buy a can of something else, or work up my own load...starting low. No sense is blowing up a perfectly good gun...and hand...and head. Hopefully, somebody will help out. I'm fresh out of .41 Mags, having just sold my as-new 3-screw BH last month, without ever having shot it, even though I owned it for 15 yrs or so. But a good 'ol Southern boy has it now, and he's a happy man.
This is from the Alliant web site. The 19 is the powder charge. It is not the xtp bullet, but is is a 210 gr jacketed bullet. I shoot a 210 gr cast bullet with 17.5 grs of 2400. I am guessing that 19grs will let you know you have a hold of something.
1.575 6 CCI 300 2400 19 1,223
A 210gr XTP with a load of 17.5 grs of 2400 in a Winchester case and Wincheser primer chrono'd at 1,413 fps average from my 6" S&W M57. Almost exactly what the previous Alliant data below shows. No pressure signs either.
No sir, that's just not true. My Hodgdon Manual #27 includes load data for not only Hodgdon, but also for Alliant, IMR and Winchester powders as well. And it includes it for the vast majority of the cartridges listed. Admittedly, none of my Hodgdon "Annual Manuals" include load data for anything other than Hodgdon powders.