I have a Remi 700 in 223 with a 1 in 9 twist 20" barrel.

As background despite trying a multitude of powders and bullet combinations it has never grouped below 1". Also the cases I have used have only been neck sized so far.

I had some Lapua brass that had been fired in a Savage 4 times. To try to ensure the cases were back on spec to use in the Remi I full length resized them.

Having reloaded them the bolt would not close on the round.

I have about 80 Hornady cases that were once fired so with no sizing done I tried the empty cases in the Remi and the bolt closed on all the cases apart from four where the bolt closed but was a bit stiff.

I full length resized those four and now the bolt will not close on them!

I don't use a hot load where the base of the case might have expanded and the full length die has been set as per the Manufacturers instructions (Hornady)

Any suggestions as to what might be wrong?