Detachable box magazines

[JKO]

I was wondering:

Would anyone here know if there's a company that makes a detachable box magazine that would fit a long/magnum action Remington 721?

I've talked to Badger Ordnance, and they said that their adaptor system (which converts a Remington 700 to take Accuracy International magazines) won't work with a 721.

Similarly, H-S Precision says that their stocks won't fit that model.

P.S.: I can't be certain, but I *may* have asked this question before. My apologies if I did, because I don't wish to trouble anyone.

Thanks.
--JKO