Theres a few Malt, TR Robb,in the uk,and Crooked Barn in the states.If i was you i would try the link below,they have everything you need to tune the rattys,and the guy that runs it really knows his stuff.Word of warning tuning rattys can go on and on,and be quite expensive.
http://www.sdcustomdesign.com/index.htm
I've spoken to Steve before, via Email. There's some cracking custom guns on his site. I was hoping to get a full length barrel off him. I'm not sure if I could get one sent through the post now though!
Thanks again for the info!
Go for it Malt,order the 24inch