Re: us model 40x 22lr
They can get pricey. They are loved by a variety of shooters for different reasons. Rimfire benchrest shooters love it because it has great ignition and when it is trued, it is one of the best rimfire actions out there. The better custom rimfire actions are in the $1,000 range, so a 40x at $500 - $700 can be a deal with a little working.
For the tactical guys, the 40x is great as a trainer because it will drop into a 700 footprint, which means it will fit pretty much any stock out there without inletting issues. If you use an Anschutz action, for instance, none of the McMillan tactical stocks will work. You are limited to a handful of varmint guns and Anschutz replacements. Also, even without work, the 40x is inherently a pretty accurate 22LR action.
As for disadvantages... it is only available in single shot. There were around 700 or so repeaters made and they fetch about $3,000 in the open market. If I were to get one, I couldn't afford to drop it into another stock... and if I did, I would probably end up needing to the stock custom-inletted for the mag. And then the price... these are pricey for what they are... old 22LR's. They are expensive because so many types of shooters want them... supply and demand.
Stiller has been working on a custom action that will be a clone of the 40x it will sell for around $700 and you will be able to get a repeater. I can't wait for them to come out with it... that will basically give the best of both worlds in a tactical trainer. I do wonder if you will be able to just drop it in most stocks. It depends on what he does with the mag situation.