Have a few bases and ring sets from auctions, unfortunately the leupolds I have are all for less than 300 win mags as can be seen on the 2 piece info, as this is one set I have #50016.
STD REMINGTON 700 2-PC MATTE
Part # 50016
Leupold® steel Standard (STD) rings and bases are the most versatile of any mounting system we offer. This specific model fits a Remington 700 and is the perfect choice for standard calibers less than .300 Win. Mag.
Like someone else said, those std bases are not good for heavy recoilers. The windage adjustable screws are a weak point. Glad to see Leupold admitting such in writing. With that being said, any base ring combo that will work on a 300wm, will also work just fine on a 338wm. Talley lightweight's even work, for what it is worth. It seems like you are preparing for a recoil that is going to rip your head off or something. That is not the case. I've actually seen many 300wm's kick harder than a comparable 338wm.
