I got a PM with a question that the community may benefit from (in general) so I will post it:
"I have a Euroarms m1861 rifle musket and I intend to retrovert this rifle back into a m1855.
I plan to use an 1855 lock plate from S & S firearms and from what I have read/researched, I will need to buy new screws and lock plate bolts to fit the new lock plate.
My question is this, will the EOA tumbler, mainspring, hammer and sear fit the new plate? Also if you have any tips/lessons learned from doing this endeavor, they would be highly appreciated."
Here was my reply...
Funny you should ask because the very first project I ever did was this retroversion exactly so I am very familiar with the challenge and it is a tough one as these things go but you hit one thing right on the head...you will need different screws for all the lock internals and the lock plate. The EoA are metric threads and the plate you get from S&S is tapped for the original threads which (I think) are something odd like 10/24. They may sell the screws or if not Lodgewood Mfg would be a good place to call for them. The lock internals including the springs for the Euroarms will generally fit with very little or no adjustment. The hammer needs to have a notch cut in the nose or else replaced with an original hammer. The stock needs to be mortised (cut out) to accept the hump of the lock plate which requires a bit of careful woodworking, but still nothing that can't be done yourself.
Several problems to overcome are greater than those with the lock, stock and hammer...the flash guard on the 1861 barrel needs to be ground off because with the high hump of the 1855 lock plate, it was not a feature of that model. The rear sight is slightly different on the later versions of the 55, or completely different if you are doing yours to be pre-1860 as most of the lock plates are dated 1857-58 (those had a sight very similar to one on the US 1842 rifled musket and located quite a bit further toward the front sight and the part costs around $250). If you do go that route, then you are going to need a gunsmith to tap the barrel in the right place and you will have the issue of the notch in the barrel where the old 1861 rear leaf sight was previously...which can not really be filled in to look like it should. That is kind of an insurmountable problem. It also takes a brass nose cap, which can be overcome by modifying an Enfield nose cap, but it again requires some fitting and woodworking.
Hence, the easiest thing is to do the later version and just screw in the correct rear leaf sight, it's easier cosmetically at least. That particular sight runs about $95. However, with the later version (with that rear sight) it had a patchbox which will be another challenge which requires not only the cost of the patchbox but also mortising out the rear stock flat and butt plate to accept it. All in all, it was quite an expensive and time consuming project. In the final analysis, I wasn't really happy with it because it was still a big, heavy, clunky Euroarms reproduction with all the other issues those have. If I had it to do over again knowing what I know now, I would probably just spruce up the 1861 you have with an original contractor lock plate. Still unique, much more common than Armory version (US Springfield marked), under represented in the hobby and much less of a headache and expense.
"I have a Euroarms m1861 rifle musket and I intend to retrovert this rifle back into a m1855.
I plan to use an 1855 lock plate from S & S firearms and from what I have read/researched, I will need to buy new screws and lock plate bolts to fit the new lock plate.
My question is this, will the EOA tumbler, mainspring, hammer and sear fit the new plate? Also if you have any tips/lessons learned from doing this endeavor, they would be highly appreciated."
Here was my reply...
Funny you should ask because the very first project I ever did was this retroversion exactly so I am very familiar with the challenge and it is a tough one as these things go but you hit one thing right on the head...you will need different screws for all the lock internals and the lock plate. The EoA are metric threads and the plate you get from S&S is tapped for the original threads which (I think) are something odd like 10/24. They may sell the screws or if not Lodgewood Mfg would be a good place to call for them. The lock internals including the springs for the Euroarms will generally fit with very little or no adjustment. The hammer needs to have a notch cut in the nose or else replaced with an original hammer. The stock needs to be mortised (cut out) to accept the hump of the lock plate which requires a bit of careful woodworking, but still nothing that can't be done yourself.
Several problems to overcome are greater than those with the lock, stock and hammer...the flash guard on the 1861 barrel needs to be ground off because with the high hump of the 1855 lock plate, it was not a feature of that model. The rear sight is slightly different on the later versions of the 55, or completely different if you are doing yours to be pre-1860 as most of the lock plates are dated 1857-58 (those had a sight very similar to one on the US 1842 rifled musket and located quite a bit further toward the front sight and the part costs around $250). If you do go that route, then you are going to need a gunsmith to tap the barrel in the right place and you will have the issue of the notch in the barrel where the old 1861 rear leaf sight was previously...which can not really be filled in to look like it should. That is kind of an insurmountable problem. It also takes a brass nose cap, which can be overcome by modifying an Enfield nose cap, but it again requires some fitting and woodworking.
Hence, the easiest thing is to do the later version and just screw in the correct rear leaf sight, it's easier cosmetically at least. That particular sight runs about $95. However, with the later version (with that rear sight) it had a patchbox which will be another challenge which requires not only the cost of the patchbox but also mortising out the rear stock flat and butt plate to accept it. All in all, it was quite an expensive and time consuming project. In the final analysis, I wasn't really happy with it because it was still a big, heavy, clunky Euroarms reproduction with all the other issues those have. If I had it to do over again knowing what I know now, I would probably just spruce up the 1861 you have with an original contractor lock plate. Still unique, much more common than Armory version (US Springfield marked), under represented in the hobby and much less of a headache and expense.