Do they examine the components of the round that are left? Pieces of the casing or primer? I'm just curious how they could prove 100% without a doubt that the round was not factory. Are they able to determine, for example, that the casing was Federal brass and contained a Winchester primer?
Possibly. On the other hand, as mentioned, all the gun maker really needs to do is determine it was not the gun's fault. And, generally, if it was really a factory round, the shooter will have, and be happy to supply proof, to both the gun and the ammo maker.
Trust me, if a round from R-P, Win, Federal, etc wrecks ANY of my guns, I am not just going to talk to the gun maker, I will be talking to the ammo maker as well.
And they are going to want things like the lot# of the ammo, (the box it came in), where/when you bought it, any unfired rounds from that box, etc.
Oh, and here's something else to consider, by the wording, even if it IS a factory round that wrecks the gun, if you have ever shot reloads the warranty is void. Now, how would they know that? sometimes one can tell.
And even when they can't tell, if they claim it, you have to be able to disprove it.
you may also note that while "no reloads" is standard boilerplate in about all warranties, Ruger doesn't say that.
Because Ruger doesn't give a written warranty anymore. They just stand behind their products.