Ok, so first off .. why would smith&wesson discontinue this rifle?? It obviously was a great choice for them to make because a lot of use like to shoot and I myself do not believe in 22lr for training purposes because there is no punch to it, there is no loud boom to it, so to me simulating training would have to be with a centerfire cartridge (like this Russian one) .. it's cheaper than the .223 (5.56nato) and it's ballistics are just about the same 5.45x39mm= 2,900 ft/s & 1,034 ft·lbf out of a 55.9gr projectile and the 5.56nato 55gr with a nosler ballistic tip goes about 3,240 ft/s & 1,282 ft·lbf so as you can see if you truly want to simulate the feel of AR-15/M16/M4 Platform i dont think the .22lr is the way to go at all.. this 5.45X39mm is by and large the best choice due to similar ballistics, similar weight, similar BANG, and similar capacity.. That's just my .02 penny's