No Question is Stupid Unless Unasked

Since the above is true, here goes! Am going to do a switch barrel gun using an Axis II XP in 6.5 CM. However, I have been told by one person that there are two distinctly different sizes of receivers and by another that the receiver is the same and only the magazine determines whether short or long action. So, not being a Savage man (More Mauser than anything), what is the actual difference? I know that a "long"
action will take all of my calibers ie., .308, 257 Roberts, 8X57 and 6.5X55 but is it necessary? Old man, set in his ways, wants clarification. God Bless and shoot safe, Y'all.

The receivers are all the same length, the difference is the magazine. They still use the same stock, what determines the length of the magazine is the interchangeable trigger guards. If you decide to upgrade the stock to wood, you will have to determine what magazine length you are using when you order.

Also the Axis is going to use small shank barrels and barrel nut. Sounds like that may have been what one of the folks you were talking to was referring to.
Pretty sure large shank barrels were only used for some fat magnums(WSM, RUM) and on target actions in various calibers.
Hope this helps

Thanks to both of you for the help. I am starting a "switch barrel" project and have never worked with Savage receivers since I am a Milsurp Mauser fan.