I agree I have no way of knowing if the magazine is the original one (as mentioned, there are no serial numbers on the mag.) also, that the rifle most certainly would not have left the factory with this problem.
The gap between the leading edge of the feed lip and rotor on the magazine is so small there's no chance of the case 'wedging' it's a direct lower shoulder contact with the leading edge of the lip and if forced the pictured damage to the cartridge case occurs.
I have a feeling it's not the feed lip that's the problem now. I think the release tab resting on the top side of the case doesn't allow the bullet and front shoulder to lift quite high enough as the cartridge is fed forward. Not much lift is required, but just a tiny amount more would I think??? resolve the difficulty.
I'm about to strip the release tab out of the receiver to examine further. We shall see!
IOWA 303 that's kind of you & I'd appreciate a look if you can post pic. Cheers, deeangeo
PS. I have stripped out the release tab and examined - it seems OK and the spring assuming orginal has plenty of tension...maybe if not original, too much tension?? It's a tight little spring. The grub screw retaining bolt for the tab are fine and were easily removed and replaced. Hmmmm..
I just e-mailed the previous owner to ask if he'd had this feed problem, also, if the magazine had been replaced while in his ownership (he'd owned the rifle for the past 18 years)