runngun
I have a 223 Rem, 7mm-08 Rem & 308 Win, all in Remington M-7!
I just went and measured them, and they are all exactly the same length as far as the action goes!
The only difference in them besides caliber is that there is a spacer in the back end of the 223's magazine!
I believe that the difference in the standard model and the youth model is only the length of the stock! Some people get by, by just adding a slip-on recoil pad!
Hope this helps you out!