300BlkTalk

I want to try some softer (AC) alloy in the BO for hunting, 142gr PB. What powder (normal 4227, Rx7, 1680, cfeblk) can be downloaded to slow these down (1500 fps?) to retain accuracy? Even min. book loads still push the alloy pretty hard. Still needs to cycle carbine gas so 231 etc. pretty much out.

4227 will get you where you want to go...but best accuracy is going to be a compressed load.

Your best bet is to get 2400 or AA9 if you want to reach your goals of good accuracy as you chase down your speed range.

Any of the powders you mentioned should work fine. R7 is possibly the most difficult to work with in that bunch.

Depending on how soft of the alloy, you might want to consider pressure and bullet deformation. In that case CFE would cycle with with the lowest peak pressure, you might get that to work with something as soft as 10 BHN. 1680 would probably be next up would a bit harder bullet.
1680 will be less sensitive to case fill as will 4227, CFE will want to be compressed.

Soft lead and fast powders are not the best mix, so that would be a consideration.

Thks, figured R7 was the slowest so might work best. I could add some dacron but it's a pita. Probably load below any book data, just don't want any problems.

CFE BLK is easier to work with to get the action to cycle throughout range of accuracy low to high....

It does offer lower chamber pressure for given velocity, and nice metering.

Lots of people have noted the crappy SD until compressed, but I still like using it.