Weatherby Vanguard Youth

[gunluvr]

Been looking for a 243 in a youth model for my daughter and noticed the W'by youth model has a removable buttstock insert 1 inch long to shorten the regular L.O.P. Does anybody own one of these, and could one saw the insert down to whatever length needed? She's new to guns and I'm not sure what L.O.P. she's going to be most comfortable with. Is there a way to measure someone's arm,neck, whatever, to determine proper L.O.P.? Hard to fit a rifle to someone that doesn't have a scope mounted.What other things should I be looking at when shopping for a first rifle for a novice shooter?