I have a 760 Remington in 300 Savage.
It came with the original magazine which is marked ".300 SAV"
and has the spacer that some of the other fellows are taking about.
I've been to 4 gun shows (Perth and Eganville) in the last two years
and never seen another .300 SAV mag for 760.
(One dealer told me that they would be at least $50.)
So what did I do?
When I first bought the rifle, I tried a bunch of ".243 Win" 760 mags and took
the one that went in and out fairly easily. My first spare mag
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This year at the Eganville show I bought a old but unused ".243 Win" mag. I when I brought it home I spend an hour sanding it and shoving it in and out (no joke) of the rifle to get it go easily. It has a strong follower spring and is my main magazine.
P.S. Don't know what "rear spacer" these guys are talking about the spacer is in the front of the magazine where the bullet tips are.