The base design of 105 light gun is quite old. The recent sighting updates were only finished around the 1990's, and of course are subject to constant upgrade. The original trail was tubular, and I don't remember a table on the prototype. The actual production ended some time ago, Royal Orrdance were the main contractors, some were even made at Wolwich. One thing I remember is that one stage the barrel underwent a 54 hour heat treatment. To get every mark including the L115, blank firing only version, you'd need about two dozen kits. :-D The traversing table was originally thought up in the 1920's. With the improvement of recoil systems on artillery the carriage would stay stable , but if you were on soft ground there was still the problem of fast traverse. As pneumatic tyres came into use when motor transport , and hence higher speed of towing, was adopted, the problem became worse, no big spokes to grab and twist. So someone had the bright idea, carry your own smooth low friction surface with you. I think it was the 18/25 lb was the first to deploy them. I'd have to check the books to get an exact story. Firepower probaly have a lot of info, they inherited a lot of local material when the Arsenal finally closed.