bronko22000

Well as long as its factory ammo, give winchester a call and have the lot number handy. They should replace it for you or at least refund your money. Big green did it for me for a lot of 17 HMR ammo that had contaminated propellant and the bullets were getting lodged in the barrel. They sent me a check to cover the replacement cost.

TN Lone Wolf

It's strange that factory ammo isn't chambering correctly. I'd do what muzzlestuffer suggested.

Mr. Longbeard

I bought a digital grain scale and I'm gonna take 3 bad rounds pull bullets and weigh each charge then I'm gonna full length resize them add charge back to case then re seat bullet back to factory length... then test fit to see if it chambers

muzzlestuffer

One more thing to try is take a black magic marker and make the entire case and bullet black then run into chamber until resistance is felt pull out round look for wear marks

Mr. Slim

if the brass is new and unfired you might want to check the length to see of the neck is too long. might need trimmed to the right length before loading and crimping.

bronko22000

Seriously I would give Winchester a call and see it there was a problem with that lot of ammo.
But out of curiosity and it may sound dumb, but did you try any other ammo? I can tell by your posts that you do reload. But the last time you fired your rifle did you pick up the spent brass? Maybe you shot at an animal and forgot or lost the spent casing. I could be that the case ruptured and there is a small piece lodged in the chamber. Seems very remote. But stranger things have happened.