Wnat a reason to buy a Sig 551 look at DSA
I just went on line and typed Sig 551 mags and by mistake typed Sig 550 mags . DSA dsarms.com has a SIg 550 drum (Beta Mag Style) for $279.95. 100 round drum. Damn!!!!
I lieki my 551A1 and I'm buying one of these today.
Honestly you are better off spending the same money on the standard Swiss mags. The Beta is pointless on a semiauto rifle. I bought an AR15 Beta mag during the mag ban, used it a few times on a semiauto AR15, which was really pointless, then when I bought a fullauto M16 I used it a few times. It quickly becomes a novelty even on fullauto. I eventually sold it a spent the money on Colt AR15 mags.
Do yourself a favor and don't bother buying a Beta for any semiauto rifle.