BSA also did a 300 cc bottle for a while- I had one for my S-10 as well as the 400cc one. Had an alligator skin cover made to fit the bottle.. looked cool and wasn't cold to the touch either. The only difference when it comes to fitting BSA and Theoben bottles back and forth is the bottle tip length and contour of the curve of the bottle. The curve must fit into the carved out area of the stock without interfering with the wood. RB