Still looking

[Moiecol]

I'm looking for load data using 250gr cast bullet and AA1680 for 450BM.
I reached the end of the internet 3 times in ten days and found only jacketed loads only. So if anyone know where I can look let me know.

[Rockindaddy]

I have not had any success with Winchester Ball 680 powder and a 250 gr cast boolit out of my 44 Mag Colt Annaconda. However the 300 gr
RCBS semi wadcutter and 16.5 grs of WW 680 works great! Good ignition and powder burn. Really tumbles a bowling pin!

[Rockindaddy]

My stash of WW 680 ball powder is down to about 50 lbs. Still trying to wear out several 44 Mags. This powder is surplus 30 US Carbine propellant. Works good in 7.62 x 39 mm, 7.92 x 33 mm Kurtz Patrone, 50-70 Govt and a 300 gr cast boolit with 33 grs of WW 680 ball.

[TurnipEaterDown]

The Western Powders guide has data for a 250 gr bullet w/ AA1680 in the 450 BM.

There is absolutely no reason not to use jacketed bullet data for cast bullets.
You will never find pressure manual data for every cast bullet in existence, and the general person you meet saying 'use this cast bullet load' doesn't know what the pressure achieved actually is - they look for gross signs and deem safe or not (in most cases).

Start with simply comparing the case depth intrusion of the two bullets (data bullet and bullet being used). If the intrusion is less on the bullet you want - use the book data to start and load to the same Velocity as the book got or stop before if you like your load (accuracy wise, etc.). If the intrusion is More on the bullet you want to use - simply cut the start charge back a representative amount on a case like this, and again load until you get book velocity or stop short if you like some intermediate load.

The Maximum Achievable Energy produced will vary a little with bullet construction differences, but not much, and in the general sense a lead bullet produces less resistance than a jacketed. So, for many applications jacketed bullet data is a fine substitution - As Long As Case Depth Intrusion is heeded, AND Max Velocity with Equal Bullet Weight is not exceeded.

Energy is really the thing here, but if the bullet weight is the same and the twist rate is the same between the data source and your gun, equivalent total bullet energy means equivalent muzzle velocity.