The bolt head is more important than the action length in your case. IIRC, the bolt head of the '06 measures .473. You can use almost any round with the same Dia. In your long action you could consider 7x57, 6mm Rem, 308, 243, 7mm-08, etc. You might try swapping rifles with someone rather than re-barreling. Are you aware that Remington makes managed recoil ammo for the 270? If you reload ( may be a good time to start ) you can load lighter bullets at less velocity to suit your recoil needs. Good that you are encouraging your GF to shoot.

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