Im not sure that they would be legal here either, but we have an FPR class with extra flexibility and rear monopods etc are allowed. Rifle has to have a magazine and a folding bipod. Basically a PRS gun shooting FTR. Mine is a Tikka T3X action with a proof barrel. GRS bipod.They do look like they would work nice but can't use them here in the USA for NRA F-Class.
. Section 22 Rule 3.4(c) Elevation Adjustable Stocks Prohibited – Rifle stocks equipped with any form of device or equipment which allows for the rear stock, or any attachments to that stock which interact with the rear bag or the ground, to be raised and/or lowered mechanically between shots through the use of screws, knobs, posts, or like devices are prohibited.
I put one on my Christensen Arms MPR(338LM)a year or so ago and use it with a small Protektor rear bag and an Atlas CAL Gen II bipod and the thing is awesome.Lots of vertical adjustment and no more fooling around with bipod height changes,squeezing(or stacking)rear bags,etc.Definitely spoiled me,as I took out my CA BA Tactical(300WM)to the range 2 weeks ago(no ABR)and spent most of the morning fooling around with rear bags and adjusting the bipod height trying to get on target.Really like mine.
View attachment 1461130