Hello, again:
Further on the import blocks:
From an Armisport importer who visited the Italian factories and assembly locations:
For some time, at least with the Armisport Spencers, when worn tooling was replaced, measurements for the new tooling were taken from the WORN items! He saw as much as .060" of dimensional variation. Dimensions of internal parts vary by production batches. The Armisport/Chiappa warranty center in Dayton, OH has not been able to determine, at least for Spencer's, which dimension part ties to a production run or serial number. It's a buy and try situation. In a few cases, owners of Armisport Spencers progressed through a few, cheerfully provided replacement parts from Dayton with no cycling success. Chambers can be all over the place and not come close to the EU approved drawing. Ask those that line them.
I have also encountered two Armisport 56-50 Spencer carbines, owned by a father and son, that would allow the complete block assemblies to "fit" in either, but one would not cycle ctg's if it had its original block. Careful measuring showed no significant variations in dimensions. The cycling problem with one was cured by swapping the complete block assembly, but it took a couple years of trying to find out why. We discovered that the one with cycling issues had been barrel swapped at Taylors from 45 Colt to 56-50 to fill an order when no complete 56-50's were in the U. S. When I shared this saga with the Manager at Taylors, Winchester, SHE told me "That could have happened". To this day, the one with the swapped barrel will not cycle ctg's's with its original block, so the father borrows his son's block assembly. The warranty aspect, which does not involve mod's that would invalidate the warranty, has been left out of this at the owner's request. Sorry to belabor.
Please be sure an Armisport upper block will be ok. Smiles.
El Supremo/Kevin Tinny