Doesnt hold up to 450 bushmaster - Caldwell XLA External Spring Shooting Rifle Bipods - Pivot Position

I bought the large one for my deer hunting gun but it never made it past the range. It was wobbly at first but when i finally got it somewhat stable the first shot made the tightening screw jump or slide over the raised sections and it would just not stay on again. Everytime i try to tighten it the bolt just slide off to the side. It seems to me that it is just too large for the components and with a heavy recoil round i say dont get it. I will only use a picatinny mount for this application.