You need to do it proper with 11.6 like we do!
...It was always a ''off the shelf'' gun sport to begin with, and old league photos I have seen and old boys I have talked to in our league seem to confirm that the guns used were normal springers. Obviously BSA underlevers dominated in the early days, but post WW2 guns like Airsporter clubs / Webley mk 3's arrived and these seemed to be the staple up to the 1980's with a few diehards still doing well with 45" CS BSA's (I have seen old score books and people were getting possibles back then and 23's / 24's were quite often seen). Now those 3 guns ran about 10-11+. The German stuff started popping up then and becoming more popular due to the weight, with several people now still using HW 80's, but I would say these days it's about 60-65% HW 77's the remainder various marks of TX200 with a few odd Webley Omegas / Superstars / others.
Many of the guns I see have been circulating in the league since the 80's with stunning early venom Tyro HW's being seemingly common...I have never seen so many since I started doing this discipline
Obviously all the leagues started with full power guns way back, but we are talking 8-9 for the shorter BSA's maybe 10.5 for the 30's long guns...I don't know how the various leagues morphed into using 6 pound guns, maybe it was because the target boys got involved and that is what they used (FWB 300's and the like).
ATB, Ed