No offense, but from the picture quality all I'd be willing to say is that some (not all) look to have punch-staked primers (typically military & commercial, never seen a home reloader do that), and the bullets do kinda look like Winchester SilverTips, which I'd never known Dominion Ctg Co. (DCC) to load with anything similar? Try taking a close look, magnified preferably, of where the crimp triangles are closest to the primers; does it look like they overlap or at least touch the primers? On a factory punch or stab-crimped cartridge they should, though when reloading, de-priming is often enough to push the edges back a bit.
Two things to consider:
1) while you should be able to identify sizing marks like others have said, if the outside of the case is too buggered up for you to be sure, look at the inside. Pull the bullet on the most suspicious-looking one or so (like with a protruding primer?), and look at the brass on the inside of the case. No matter how well you may clean a fired case (especially a bottleneck type), I've never seen a fired reload look anything other than pretty black inside.
2) You want to risk a rifle on some old shells of unknown origin that you got in a trade? I wouldn't. Re-using diamantled components? Done that, lots.
I don't fire other folks reloads either. I and others trust my reloading, and I trust several guys I know's reloads, but I don't fire them. It's kinda like 'what's good for them is good for them, & what's good for me is good for me. I was on an IPSC Black Badge course many many years ago where a guy borrowed a pistol from one guy to do the course (while his was out with a gunsmith for mods), and ammo (reloads) from another guy, because he wasn't set up for that calibre yet. End result; he ended up owing one guy some brass, and the other guy a barrel, bushing, link, and pin for a Colt Government model after clearing a misfire and splitting the barrel from the tip of the muzzle to the back of the lug when the next (possibly over-charged) shot apparently drove two bullets form the bore. Those reloads sure didn't save him any money. Not worth it...
-You rifle, your ammo; your call.