Curious about marks on Winchester P14

Recently bought two P14's: one had Winchester action/ barrel fitted into a nice ERA "fatboy" stock, the other a nice all matching ERA action/ barrel fitted very, very poorly into an M1917 stock. I've swapped everything ending up with one totally ERA rifle and this one. Have now properly inletted the M1917 stock and it's looking OK but rifling is quite washed out near muzzle and I'm not expecting great things from it. The photos show most of the markings on the Winchester action body/ barrel and I'm curious if any of them mean anything to anyone. Specifically, "MNS" is present in 3 places, along with a shamrock on the barrel and VP in a circle. Thanks, in advance, for any info.

Ridolpho

VP in a circle is a Winchester proof mark, Visable Proof
MNS
Midvail Nickle Steel

Chuck: Thanks- so Midvail was responsible for producing both action bodies and barrels or just supplying raw materials?

Ridolpho

midvail steel provided steel for barrels, actions and bolts for winchester, for actions on all 3 makers.