[Fanky]

I was trying out my new Marlin 1895 GBL the other day with some Winchester 300 grain hollow point ammo. I only took 4 shots with it to check function, and noticed the primers were visibly backing out quite a ways. I also noticed that the rest of the rounds in the package seemed to be excessively crimped. I don't have any pictures handy, but the primers backed out at least half of the primer's height, but weren't flattened or cratering at all. I'm probably just going to pull the rest of them apart and try loading them up once I get some dies, but was just curious what other insight or experiences could be shed on the subject.

[rcmodel]

Probably nothing to worry about.

The 45-70 is headspacing on the rim.
Rim thickness and chamber variations create excess headspace.
Too low a pressure to reseat them.

Primers all back out to a certain extent.
Rimmed calibers more then rimless.
Lever-actions more then bolt-actions.
But then pressure slams the case back and reseats them.

Yours are loaded to a low enough pressure the cases grip on the chamber isn't being overcome so they can reseat when the case comes back against the breechface.

It is very common in 30-30 lever action factory loads too.

rc

[Fanky]

That does make sense now that you mention it, RC. I was assuming that most factory 45/70 is loaded pretty anemic in case it's loaded up in an old trapdoor by accident, but I never looked at low pressure being the suspect. Guess you learn something new every day.