Home Forums Hunting & Shooting Hunting Rifles Help: Ammo won't chamber!! (but brass will...)

Yes, my handload is seated out into the throat for my Tikka. I wasn't shocked that it didn't fit the Cooper.

But why in the world would factory winchester 243 ammo not fit? I thought this was one of the draws to an AI chamber...using the vanilla caliber rounds to fireform brass to the chamber.