I believe the trial carbine may have been a Mk II** with the barrel shortened to 26". T.R.R.S. also presents a Mk III with a barrel shortened to 26.5" as a possible carbine modification for cavalry use. However, that example is suspect, since the stock has been slimmed and the right face of the butt scrubbed. It would make sense that, at that point in time, a trial carbine would be assembled on a Mk III platform rather than a Mk II. The trial carbine was intended for cavalry use, so the Mk II platform might have been chosen due to it's lighter weight and lack of a protruding magazine. Sir Sam Hughes was not in favor of rifles with shortened barrels, so the project was shelved .