A good rule of thumb in these situations is, when a firearm works fine with most ammo but has a problem with one batch of reloads......it's the ammo.
A sure way to find out is to buy some factory new ammo and try it.
If it works, the problem is the reloads and a smart shooter will discard the problematic reloads, or break them down for the components to be reused in better quality reloads.
A not so smart shooter will try to use them, possibly in another gun.
If the reloads are bad enough they won't work in one gun, that's a pretty sure sign of a poorly loaded batch.
Question is, what ELSE may be wrong with it.
The what else can take the form of "Oops, I just blew my expensive gun apart" or "Oops, I just did serious damage to my hand or lost an eye", or "Oops, the poor guy standing next to me just got hit in the head with a piece of my gun, wonder if he'll sue me"?