Has anyone had any problems with Magtech ammunition - especially .44
magnum?

I had a Henry Big Boy jam with the lever down and a cartridge only
partially out of the feed tube - totally locked up, and I couldn't push the
cartridge back into the tube or raise the lever past it.

I have trouble believing anything wrong with the cartridge could cause
problems in a lever gun (except, perhaps, a _very_ long OAL), but my
gunsmith swears it is a cartridge problem, that he has seen problems with
Magtech .44mag in other [types of] guns, and insists I shouldn't use it.
I'd previously fired a box of 50 out of the same case with no problems, and
the first dozen or so out of the current box caused no problems - if the
assembly line has sloppy quality control, though, that probably doesn't
mean anything...

Anyone have any experience like this? I've only seen a couple of good
reviews of Magtech in the gun press, and no negative ones, but I don't read
all that many commercial gun magazines so could have easily missed all
kinds of discussion about it.

Cheers,
Rich