I found a link over in Rimfire Central that mentioned that Promag was going to make a 20 round magazine for the 17 HMR for 10/17 Rugers and so I went to Midway USA and found that Promag is also making a 22 round .22 magnum magazine for the 10/22 magnum Ruger.

Also -- besides the 22 magnum and 17 HMR, check out the 22lr Hi-Caps -- one is a 50 round drum mag.

www.midwayusa.com/esearch.exe/search?TabID=6&category_selector=all_products&search_keywords=ProMag+Magazine+Ruger+10%2F22&Click+to+Begin+Search.x=15&Click+to+Begin+Search.y=7

and they are probably gonna be as great as the other pro-mags

And did you read the 1 comment ?  It didnt even fit in the rifle,.......keep up the good work promag.

I have a friend that uses the Promag HK USP .45 mag, and they work.  Don't have any experience myself.

Quoted: And did you read the 1 comment ?  It didnt even fit in the rifle,.......keep up the good work promag.

Not sure what magazine you're talking about -- neither the 22 magnum or the 17 HMR magazine have been released yet. There was one post in RFC about a magnum magazine not fitting but that was a factory Ruger mag and the problem seemed to be the non-factory stock.

Some people have problems with different brands of aftermarket 22lr mags but the ProMag 22 magnum and 17 HMR mags are going to be the only Hi-caps available for those rounds. The after-market magazine thing is a crap-shoot -- they either work for you or they don't.