I was wanting some technical info on Double Rifles (Not specific to any particular make, calibre etc) My understanding is that regulation of the barrels is where the art/science and cost comes in. Firstly, so as I'm not starting off with the wrong info, is regulation the aligning of the barrels so that at some point in space if a bullet is fired from each barrel simultaneously they would hyperthically collide? Assuming that is correct; is there an optimum distance that this should occur and if so is this dependant on a particular calibre and its designed use. Eg. a 470 nitro express might be regulated for 100m and a 375H&H for 200m?? Do the gun makers have standard distances for certain calibres and if so what are they? My understanding is that load development also takes on a critical part of the equation. Did/do the famous/expensive gun makers (Rigby, Holland and Holland, Purdy Beretta etc. no offence to all the other fine gun makers I haven't mentioned) develop an optimum load for their rifles and if so do they publish this info or advise the client what it is, or is it up to the client to work this out for themselves? I would imagine that like any other single barrel rifle, a double rifle performs better with one load than another. Actually, it must be more difficult to find this load for a DR as you are dealing with 2 seperate barrels. I know DR's are not designed for target shooting (this subject was brought up earlier) but you still don't want one barrel shooting totally different to the other. (once again, I guess this is where the expense comes in) Anyhow I am hoping for some info and perhaps some good discussion might occur. If these questions have been asked before, I appologise. I haven't had the chance yet to review every post on this Wonderful site. Thanks to all those involved.