Changing the internal dimensions of a rifles chamber

[RB II]

Make up a dummy round with the bullet resulting in the longest CBTO measurement (you said you'll live with the longer jump for anything else) and give it to your smith when he gets back; tell him how much jump you want based on that round.

Keep in mind, the 22-.250 is a throat burner- you can smoke one in less than 500 rounds, or stretch to a couple thousand maybe if you keep loads light and don't light it off like a MG. It won't be long until you're chasing that freebore as the throat wears away- so keep that in mind. Depending on how much jump you generally like- you may want to consider seating that bullet a little deeper than you might like initially because that will allow you to seat further out as the throat wears initially, while maintaining the same jump.

Already have the dummies ready for him to get back. I also am intending to shoot the 169 TGK, which is a shorter bullet than the solid copper. Have a dummy for that load as well. Might have him throat for the 169 and chase the burn out as it occurs.

I am taking it PD hunting in May so lots of shooting of the 55 gr. I may not have him work on it until after that hunt as I won't shoot any heavies there.

Got a range bag full of test loads, one of which is the 70 HH seated 20 off the lands. It is as short as the 55 grs. But going to see if it will shoot like that. Maybe!!! Will report back.