45-270-SAA 280gr bullet, best load?

[gilgsn]

Hello,

I just got the 45-270-SAA RCBS mold, and I can't wait to try it..
(I do have the Brian Pierce article by the way..)

Which of these loads should produce the best velocity with that bullet in a 4-3/4 barrel without too much pressure (Pietta SAA):

1. 8gr of Unique.
2. 16gr of 2400.
3. 17 to 19gr of IMR4227.

Any other suggestion?

Also, I measured the chamber throats at .4525. Would it be better to size at .452 or .454?
I wish .453 dies were available..

Thanks!

 

[DWFan]

The first two loads you list are part of the 14 kpsi group; the 4227 load is on the 20 kpai table and only at 19 & 20gr. The Hodgdon website doesn't list 4227 as a potential powder for the standard pressure (14 kpsi) Colt loads. The load I hear about the most is 7.5gr of Titegroup with that bullet and should give you approx. 950 fps with your 4 3/4" barrel. It's listed with the 14 kpsi group.

 

[USSR]

Of the powders you listed, you will be better served with Unique. 2400 is an excellent powder for the .45 Colt, but is best used in larger quantities and higher velocities than are possible in you gun. Forget 4227, it's even slower yet and burns quite dirty, leaving bits of unburned powder kernels in your gun. Other powders worth trying are Red Dot and most any powder suitable for 12 gauge shot shells.

Don