A few weeks ago I took my dad's S&W 4516-1 to the range (it's of course chambered in .45) but every so often it wouldn't go back into battery, the slide would stop about an 1/8 of an inch or so. We called S&W and they sent us a new recoil spring after I installed it I took it back out and it was still failing.

I was using 3 different kinds of ammo, steel cased Russian called Monarch, Winchester white box and some of my friend's hand loads (he cast his own bullets)

With the steel case it fail on almost every shot, friend's hand loads failed maybe every 3 to 5 shots and the Winchester white box shot perfectly, not a single malfunction if I recall correctly.

Any recommendations?

Thanks y'all

It's the low power ammo. Stick to shooting good ammo and it will be fine.

Sounds like it may have a tight chamber...steel cased ammo can be very finicky in some S-A pistols, same holds
true with unknown/non factory (sized) lead reloads...

I would take the dimensions of the factory Winchester white box ammo with a digital caliper and compare them to
the steel cased and the cast lead reloads and see what you find...

Steel cased ammo can sometimes be loaded to lower power levels and often using rather no so clean burning powders,
after all they are  sold as bargain ammo for a reason.

If it is found that the barrels chamber is very tight it is a rather easy fix, some Flitz polish and a felt bob on a Dremel
tool and a mirror polish later to the chamber should resolve the Issue...

Good luck.

Steel case isn't as 'slick' as brass.  it doesn't feed as smoothly, or as fast out of the mag.
Reloads can be slightly oversized, or slightly scuffed and rough.
Factory ammo in new brass is the right size and slick... it's usually the least failure prone (although my reloads do better.. I'm anal like that).

I tend to consider a weapon 'combat reliable' when it feeds the cheapest / nastiest steel cased ammo with ease.

I'd consider that an 'ammo' rather than a 'gun' problem, and use quality ammo.

There's a perception that a 'quality gun' should be able to run on anything, but out-of-spec sizing, below-minimum power levels and rough/out of true case heads and walls aren't the gun's problem; if it runs on WWB, in my opinion it runs.


Larry

I agree with this  being an ammo problem and not a gun problem to a point.  I also think the chamber is tight and you would benefit from finding a gunsmith with a chamber reamer and have him ream the chamber.  Clymer makes a reamer that is 0.0005" larger than SAAMI minimum.  Even 0.001" over minimum would work for a carry gun.