Marlin 44 seperating cases

[bmortell]

I just got a new marlin 1894 44mag and when shooting handloads the cases nearly split in half on the first fire and usually does on the second, the front half is a loose friction fit in the chamber at that point and falls out from a brush down the bore. It does it with new and many fired starline brass. Loads were avg charge 4227 with keith and 11gr unique with keith. Bullets loaded .430 - .432 and chamber easily. The damaged cases measure .455 from the mouth down and .458-.457 from the stretch down.

With the gun i got pmc 180gr ammo fired em, loaded 1-2 times more and they are fine for some reason.
Any ideas whats goin on?

[fcvan]

I have no experience with a Marlin 44, but do with an 1894 in .41 Mag. I have not had your experience either. I have read however that the head spacing can effect case life. It sounds as though the mouth of the case is gripping the chamber wall and the bolt face may have some play. The cases look like halfway back in the chamber it is opened up so not getting as much 'grip' and so causing the brass to stretch right where the chamber opens to .457/.458 as you described.

How long have you owned this rifle? Did you buy it new? How many rounds down range? These things could determine if the bolt face is setting back upon ignition due to wear. It also seems the chamber may be faulty. If it's a newer gun the chamber might have been cut with a faulty reamer. SAAMI chamber dimensions call for .456 at the case mouth and .457 at the base. Cleaning up the chamber with a new reamer might make the chamber grip the case more evenly and eliminate the stretch. I'm just guessing, there are real experts here. I hope they chime in with their expertise.

[bmortell]

The gun is brand new and ive only shot maybe 50 rounds, none of them hot rod loads either so its not worn out. I agree with the chamber shape and the front half gripping, just dont understand why it did it to starline but not PMC cases, my only theory is that maybe the factory bullets have a resdue or coating on the brass from manufacturing and starline is raw brass, and maybe raw brass + fresh machined chamber is just too much grip for the amount of bolt play.

Hopefully im wasting my time worrying about it and starline cases will be fine after the chamber is good and carbon-ed over. Tommarow ill get it dirty with some loads that dont make enough pressure to case seal the gas and then fire some magnum loads in new starline cases and see what they look like, unless anyone has a better idea first.

[BK7saum]

My initial thought is that it is a headspace issue and needs to be returned to the factory.

[TCFAN]

My 94 marlin 44 mag. Cowboy did the very same thing as yours. It quit when I stopped using old reloads I had for my superblack. Bought new brass and started using .433 boolits and never had a problem since.

[Skipper]

Since it headspaces on the rim, check the Starline rim thickness vs the PMC thickness. Sometimes you can adjust the thickness slightly by peening the rim with a center punch.

[Jeff Michel]

Get some new brass or you can anneal your old brass.