The old Remington 514 was a very cheap rifle and the barrel was very soft steel, compared with others of it's day, as well as today's steel. Examining the chamber, after cleaning, the belled area located between the short and long rifle shell lengths was quite pronounced. To make matters worse, the extractor wasn't as good as in other rimfire rifles of it's day.
The rifle cost less than $20 in the mid-1950s, so it was basically a "throw-away" starter piece, but it shot well for a long time and could have worked for several years if I hadn't shot .22 Shorts in it. I got tired of prying LR shells out with a pocket knife, so it was time to let it go.