I have a carbine barrel that has been rechmbered by Mike Bellm to 375x444,I also have a 375JDJ. My question is the JDJ rounds will chamber in the 375x444 are these safe to shoot? The difference is the shoulder length, I believe that this would be like fireforming for a improved round if the rounds were interchanged. Also does anyone have any experence with the 373x444 in a carbine barrel?

I HAVE BOTH A 14" 375JDJ AND A 23" 375 X 444 BELLM AND IN MINE I CAN SHOOT THE SAME SHELLS. I HAD A AMMO MANUFACTUER MAKE A LOT OF 100 375JDJ LOADS AND THEY FIRED FINE IN EACH BARREL EVEN THOUGH I KEPT THE CASES SEPARATED FOR EACH BARREL SO THAT THEY WOULD BE FIRE FORMED TO EACH BARREL. I DONT SEE ANY NOTICABLE DIFFERANCE IN THE CASES,BUT IT COULD BE DIFFERANT IN MANY INSTANCES BECAUSE MIKE COULD /WOULD CUT THE CHAMBER DEEPER IF NESSASARY TO CLEAN UP THE THROAT .I ALSO BOUGHT A SET OF DIES WITH EACH BARREL THAT WERE CUT AT THE SAME TIME SO THAT THEY MATCH EACH BARREL.AS FAR AS BEING SAFE I GUESS THAT DEPENDS ON HOW YOUR CLOSE THE BULLET IS SEATED AND HOW THE CASE FITS. I GUESS THE ANSWER TO YOUR QUESTION IS MAYBE.BOTH ARE FUN TO SHOOT I HAVENT CHRONO'D ANY LOADS YET BUT PLAN TO THIS SUMMER.ERIC

They're both a 375 Express.

Good day,
vhram, you mentioned you had an ammo manufacturer make up some ammo for your 375/444!What headstamp came on the brass?
Mike

it was 444 brass