I picked up a "Gander Mountain Exclusive" - A Rossi single-shot 'matched pair' combo in .22 LR, .243, and .410... It comes with a shorter composite stock but it's still long for my son (he'll be 4 this spring). Does anyone make something like the 6-position collapsible M4 stock for this Rossi? I'd like something that will fit my son better so I can ease him into shooting with the .22 LR.