So I have a model 10 McMillan on order, but it looks like it is going to take a couple of weeks to arrive. In the mean time I am shopping around for a bipod. I have pretty much settled on the Atlas BT10-LW17. My main question is can somebody take a measurement between the two sling studs on the forearm of the stock, so I can figure out which length rail I should get (3.5" or 4") Also, If anybody has mounted one of these bipods on their rifles I may have some other questions for ya.