We have often touched on the series of US magazine rifle trials that took place through the late 1800s – those trials brought out a slew of interesting new ideas and clever (or not so clever) designs. However, the trials were also responsible for an experimental version of the old standby Allin conversion Trapdoor Springfield.
In order to have some rational standard to judge the new rifles against in the later trials (after the .30 Army, aka .30-40, cartridge had been specified instead of the old .45-70), the Ordnance Department decided to rebarrel a handful of Trapdoor rifles for the .30-40 cartridge. These would act as the baseline against which the recoil, accuracy, rate of fire, handling, etc of the new designs would be judged. Few if any of those original conversion exist today (I have not ever seen one, but I suspect one or two are probably in museum collections somewhere), but I did have the opportunity to try out a modern reproduction of the pattern made from original parts.