Just went through this in 300 BO. Normally shoot 3085 in tight chamber carbine. BUT other 2 will take 310 easy. So how do you find fit? I slugged the 30/30 years ago, never chamber cast. I PC and it is easy. Remove your barrel. Use a fired case from the PX4, your chamber is a couple thous. larger. A 357 bullet will probably fall in. Seat an unsized PC bullet a tad long, Tap it into the chamber. Tap back out with a wood or brass rod. Look for marks on the PC where the bore/chamber scrapes. If the case won't chamber, bullet is too big. Roll size it. I use 2 10# barball weights, roll the bullet in between.
What I describe is really just a 'plunk' test and you should do it on all your loaded ammo! Just start big. Simple and cheap.
PC with ~50 and ~teaspoon of powder in #5 plastic bowl, thicker the wall the better. Sometimes I wear cotton gloves, swirl a bunch - builds up the static and up/down to 'puff' the powder. Low humidity helps a bunch - moisture absorbs the static. A little technical here but you get static from friction of the powder/bullet on the tub wall which is an insulator. Thicker wall, more insulation! After coating, knock off excess - I haven't done the dump method yet. Keep stored PC dry.