To get the best acurecy out of a 300 win mag would be to start reloading;moly coated 175 grain sieara matchking, N560 vita vuri powder and winchester brass. Expierment with with diferent charges I had the best luck with 75gn. BUT! the older models can not take that hi of charge. Seat the bullet out to about five thou. behind the rifling. but if you dont want to reload then the best ammo would be
BLACK HILLS ammo with 175gn matchking molly
note
the matchking does work great for hunting "great expantion"
If your barrel is marked .300 Savage then you can shoot .300 Savage ammunition by any manufacturer. I do not know of a "300 Savage Winchester Magnum".
300 win.
No, the 300 ultra mag cartidge is not interchangeable with the 300 win mag.
Only what it is chambered for.
Yes,Remington designed the round, and it can be fired in any good quality gun chambered for 22-250. Just as 300 Winchester Magnum was designed by Win, but any make of 300 Win Mag ammo can be fired in any good firearm designed for 300 Win Mag.
Best to ask a gunsmith for assistance.
Best left to a professional gunsmith.
.300 WM is larger in calibre, it has a longer case, and it generates more energy.
Rifle chambered in one of the cartridges named Winchester Magnum- such as the .300 Winchester Magnum- or .300 Win mag for short.
Information about the 300 Win Mag, also known as the 300 Winchester Magnum can be found on the Wikipedia website. Videos about this item can also be found on YouTube.
Biggest physical difference is case size and lack of belt on the RUM
The M69 suffix identifies your 300 win mag as being a browning BAR that was made in 1969.