I have a left hand Ruger SS rifle on order in caliber 300 win mag. The action will be rebarreled to 338 Win Mag. Since I have had this rifle on order for 3 months I am exploring other options. I have seen some used 7mm mag Rugers for sale and was wondering if there is any difference in the feed rails, etc between the 7mm and 300 Win Mag?
Looking for the easiest possible conversion to 338.
Thanks

Though the 7mm Rem Mag and the .338 Win share the same case, outside of the fact that the 300 is a tad longer, the case taper and dimensions at the shoulder are virtually identical betweeen the two. You will be fine either way.

Malm is correct and just to add more info...
The Ruger action feeds from a combination of mag box feed lips (rear and body of shell) and action feed lips (shoulder area). As Malm said the body dims between the cartridges are essentailly the same, so there should be no problems.
The combined feed allows more combinations of calibers with fewer variations of feed geometry.

the ruger mark II is exactly identical inside ... the ruger feeds 95% out of the mag box rails, which is exactly the same in the 7, 300 and 338. the mark II has a wide flat ramp... the rails only come into play on the last 1" of the case.. which is the same on 7, 300,338 and 458

the ruger box is about 3.4 interally...

and i have had to do ZERO ramp and rails to have it feed the 416, 458, and 470 ar, testing the various rounds in the 470, which was a 7rem to begin with.

only the original rugers, tang safety, have a different ramp... but their mag boxes are also identical from 7, 300, 338 and 458.

jeffe

Thanks Jeffe. You are the man! I am getting tired of waiting for the 300 Win mag to come in. I might as well buy a used 7mm since it is for a project anyhow.