The magazine spring broke on my Mark V 378. Can't seem to find one on the internet, anyone know if a spring from another rifle will work? Thanks!

While the 378/460 followers are proprietary and cost roughly the same as a small, 2 bedroom bungalow in Las Vegas, I believe the follower springs in all of the Mark Vs are the same in the long actions. But I have been wrong before. As far as putting in a 700 or model 70 follower spring, you would just have to try it and see.

Before the mid 1990's they used a different magazine spring for the 378 and 460, a taller, stronger that the std spring.

They apparently they ran out and then started using the std MV magazine spring.

I made some copies of the older heavy spring a number of years ago and still have some. If interested drop me a PM.

J Wisner