I have a 60 round Surefire for 223/556. Seems to work pretty well.
We were looking at a Surefire 60 rounder when the topic of quad stack magazines came up. I am not sure if they use the same system. The Suomi uses tapered dual springs, two followers, and has a stop for one follower to prevent it from interfering with the other follower. I would like to see a similar video on the Surefire magazine.
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