Traditionally, .22 LR pistols are equipped with 10-round magazines. This includes the Ruger Mk IV and Mk IV 22/45 lines of handguns.
Tandemkross makes a range of accessories for rimfire firearms. One of the company’s newest products is the Maximus Plus 1 Follower. This follower allows a shooter to stuff one more round into a Mk IV magazine to give him or her 11 rounds on tap. One additional round may not sound like a lot, but for competition rimfire shooting where 11 round magazines are allowed, it can help improve your times.
The follower is made to fit standard Ruger magazines and should not decrease feeding reliability. They are tested to make sure they work will all factory base plates and the aftermarket bumpers made by Tandemkross. However, the company does note that combining the +1 follower with the +1 pad does not combine to allow 12 rounds into a factory-sized magazine. 11 rounds are still the maximum.
The follower is made of a red polymer that gives a shooter a high visibility was of telling that a magazine is empty. The below video gives you additional information on the follower including a step by step demonstration on how to install it:
Tandemkross sells these in packs of two. The suggested retail price on a two-pack is $24.99, though, at the time of this writing, it appears they are on sale for $17.99.