Konstantin,
Turnscrews (what some call screwdrivers), no matter how expensive, are made to be especially ground by the new owner, to fit specific pins (what some call screws), so you are most unlikely to find pre-ground turnscrews to fit your gun/rifle. Different British makers of the past, used different turnscrew design patterns, so unless you can find an original case, or picture of it, with accessories, from your rifle maker, you are unlikely to determine exact design type. Buy a copy of an original catalog originally sold by maker of your gun/rifle, and look in that, to find pictures of cases and accessories originally sold by your maker, to determine design type of accessories, etc. One source for such copies of early catalogs is in U.S.A. (do a google search for gun catalogs). Buffalo Horn handles were available, as were real ivory handles, and wood handles, etc. Personally, I like buffalo handles. Such tools can be bought from custom makers, who work to duplicate original tools. In trying to find some original ones, try the following: peterdyson.co.uk, and finesportingcollectables.co.uk, and online website, Micks Guns in UK, and there are other locations too. If you decide to buy modern copies of original tools, search for them on websites. They are available from numerous dealers; most of these modern tools are made in India/China, as you would imagine, except of custom made by one of the few modern custom makers. In aforementioned catalogs, from your gun/rifle maker, you will see the original type cleaning rods sold by maker of you gun/rifle when catalog was originally printed. Let me know if I can help any other way. Best, Jack