OK, I'm getting it now. I would suggest you keep your Garand brass separate from the bolt gun. You can save a lot of grief with the bolt gun, if you only use brass that has been fired in it only, starting with new brass.
If you just get a Lee Collet Die, you should be able to size brass that has been fired in the bolt gun only for quite some time. And instead of buying a new body die, you could use the FL die you have now to size the body and bump the shoulder back should it become necessary. And in fact you can even use use the FL die to essentially neck size only, by short stroking the press so only about 2/3 of the neck is resized. Like using a collet die, if you keep the brass separated, you could get away with that for a long time too.
Another, but a little more complicated (and expensive) option on the bullet seater is to go to a Micrometer adjustment style. See link below. It lets you set the seating depth for a variety of bullets for both guns and simply record them. The micrometer lets you easily go back to each individual bullet setting, with no die adjustment other than the micrometer setting.
Forster Ultra Micrometer Seating Die