My Hornet is also one of the older 158 models. I've never full length sized a case for it, and have no problem chambering my reloads. I do know my rifle has a slightly irregular chamber though, and I always load cases in the same orientation, (first letter of headstamp name up).
If you're having problems, you may just have to FL size your cases, but you could try putting the case back in the chamber in the same position each time. From what you say, trying them all, culling the ones that stick, then finding more that stick when you try the "good ones" again, it sounds like a similar situation to my own rifle.
By the way, mine shoots very well, so I would say the chamber is not a problem for accuracy.
In any case, I doubt the trouble is with the brass. I use mainly Remington, but also have WW, Prvi, and Hornady. The only ones that do not make it more than six loads is the Hornady brand.