I watched a Youtube video where the channel creator explained the "Rim Jam" or "Rim Lock" that happens loading an Enfield. He stated that the reason for present day rim lock is due to the newer 303B SAAMI brass doesn't have bevels on the rims, and are essentially square. These square rims cause the rim lock, where the beveled rims allow the rim that is behind another slide over and rim lock isn't an issue.

I knew there had to be some reason my No.4MK2 would rim lock every time I tried loading the second original patterned staggered stack clip. Heck, it even rimlocks on the standard staggered rounds in the clip. So, what is this bevel? What does it look like? Can someone post comparison photos of new vs old rims?

This really made me question how the Enfields were regarded as such great battle rifles. This rim lock couldn't have been going on back in the great wars, or it would be regarded as the worst rifle in history, and that is not the case. Lol