for what it is worth. Have a model 70 XTR push feed (1986) 300 win mag with magazine box marked BF. I moved the box in the magazine back and shorten the bolt stop to go from 3.4 to 3.6 inches. My mistake was fiddling with the feed lips of mag box and rifle would not feed properly. Was going to order a replacement box but the BF was discontinued. Pulled mag box from a FN controlled round feed long action 25-06 marked ML. The BF and ML box where same dimensions and the ML box cycled cartridge's in the 300 WM flawlessly. So ended up reshaping mag box lips on the BF to match the ML box and rifle cycles perfectly. only thing I did with mag spring and follower was to repin the spring further back on the the floor plate so the follower sits towards the rear of the rifle just a smigen more. Short answer is the ML box will work.
sorry for the confusion, I have a long action that has been customized and currently running 220 swift barrel which is basically shot out. The gun is currently using a L/A box “A” with a spacer which I believe is similar to .308 length. I hope this helps.
Thanks to everyone that has taken time to reply to my post.