Case sizing may or may not be a factor. I kinda doubt it as a slightly oversize case would not increase pressures. It would make it hard to chamber and extract.RR said:Fogducker
If they were small base They would have a SB after the caliber stamp.
First I am going to explain something you all probably know.In lever,pump and semi auto rifles they usually have a slightly shorter chamber , There are some exceptions to this old winchester such as 30-30 and 25-35, all the savages, I am not sure about Browning as I have only loaded for a223 in a BLR.The point is cartridges loaded in ordinary full length dies tend to either jam tight or not chamber fully.This is what Small Base dies are for.
As for the SB die thing, I load for 4 different Remington pump CF rifles and just use regular dies for all. FL re-sizing is enough for smooth chambering, but results may vary.
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