7mm rem mag to 7mm STW magazine conversion

I have a used savage 110 tactical in 7mm stw that I want to change from single shot to a drop out mag. It was a 7mm rem mag with internal magazine originally. I dont know if this can be done since the 7mm rem mag cartridge is 3.29" and 7mm stw is 3.60". I think I need RUM length magazines but I dont know much about changing the magazine setup. Any input would be helpful. Also looking for a place to get quality stocks for this. Thanks

AFAIK Wont work except single feed.
You need a RUM length Action.

You could build a 7mm/375 Ruger and that would fit in a normal long action. Been thinking about one myself.