Quote:I have a trapdoor that has been cut down to a carbine configuration in 45-70. I am thinking about having the barrel re-bored to 50 cal so I can turn it into a 50-70 govt.Jesse
Hi Jesse -- If you wouldn't mind, may I ask you your intended use of the 50-70 carbine length Trapdoor ? As you may know, the Springfield Trapdoor was a breech-loading conversion after the American Civil War to use up the existing war surplus .58 Cal muzzleloader percussion rifles for their various parts.
The Trapdoor (T.D.) was not designed off of a clean sheet of paper by Springfield designers. The breech piece was original, but the side hammer locks and the barrels were civil war surplus, used up and to a point that the war surplus was exhausted.
The 50 Cal barrels for the T.D. were surplus .58 Cal M.L. barrels that were shortened and threaded for the T.D. breech piece. The .58 barrels were reamed out to accept a 50 Cal liners which were brazed into place. if you were to look carefully at a .50 Cal T.D. rifle muzzle the braze will be apparent.
Of course, Springfield dropped the .50 Cal and relaced it with the more accurate .45 Cal which had a three land and groove barrel arrangement. For modern target shooting, people line the old style .45 barrel with a six or seven land and groove style and wipe (assume B.P.) between shots. Think about it.
If you do replace the .45 with a .50, the existing extractor will work fine with a minor alteration. that being reducing the length of the spur which is forward of the case rim, by using a fine mill file. Explaination; the existing .45 is a smaller O.D. case and the .50 is a larger O.D. case. Therefore the .45 extractor spur will be slightly too long when used with the .50 case. Action is to shorten it by the trial and error method (Read take a little off at a time until it works smoothly)
Keep in touch.
Creedmoormatch