I have a Rolling Block rifle barrel, I purchased it along with the receiver and from from what I tell the barrel is not original to this particular receiver. My problem is trying to figure out what cartridge the barrel is chambered for. The fellow I got it from stated it was in .43 Spanish of which I have two rolling blocks at present. My Argentinian is chambered for the bottleneck .43 Spanish round and the other is in the Reformado round. I have no Reformado brass but one of my Argentinian .43 rounds will chamber in the Reformado chamber, it's my understanding they both use the same brass, one is just bottleneck the other is not. The new barrel, although it resembles the .43 Reformado, will not chamber my brass, it will start and then it gets hung up. I have some Carosafe and can make a chamber cast but once I do where can I go to figure out what round it is a cast of? This barrel in pristine inside and I would really like to use it to replace the barrel on another rifle the the bore is a sewer pipe, but I need to find out what I have before I start that project. Any help would be greatly appreciated.