Gentlemen I am new to your forum. I am working on a 20ga 3.5" magnum slug cartridge with a sabot/bullet in the 240-265gr weight. I have taken a H&R 20ga Ultra Slug Barrel 24" and reamed the chamber out to a full 3.5" work has been done by a professional gunsmith reamer was made by Pacific Tool&Gauge.
My question is What powder's can I use that will get this into the 2800-3000fps while keeping the pressure under 35000.
The brass case's were made by Rocky Mountain Cartridge. As a crude gauge I measured 176.5gr of IMR 4831 to seated sabot . So I believe that
that this is close to a maximum charge. I believe that this powder would prove to slow and pressure to high for sure.
Any Ideas can not get any help from the big boys as always. Ideas suggestions Gents??

176.5 gr. of IMR4831? Isn't that the same load that they launch the space shuttle with?

I talked to IWillhunt and suggested to
start with lighter sabots and 90% fill
of W-760. His cases fit chamber tight and ball powder will cause least amount of expansion,
while getting him the velocity he wants.
Also advised him to weight gun and get a big pad.Ed.

accuratereloading.com has developed a new powder just for this type of round...it's called BBBruce and it's perfectly designed to create a very large amount of hot gas for large cavities.

Recoil will be light using this new powder as it barely moves the bullet (or anything else for that matter) but it makes a helluvalotta noise and can be fired often with no cost at all.

sorry IWillhunt....I couldn't resist....

quote:

Originally posted by IWillhunt:
As a crude gauge I measured 176.5gr of IMR 4831 to seated sabot . So I believe that
that this is close to a maximum charge.

Where in Colorado do you live? 'cause I don't want to be anywhere near you when you drop the hammer on that load in a shotgun barrel

Just an FYI, Shotgun powders tend to be fast like pistol powder(s). As a matter of fact sometimes they are interchangable. Note that a typical load for around 1 1/8 oz. of shot is 35 - 45 grains.