I fired my MkIV Martini-Henry for the first time today. The rifle is a IMA rifle with a pristine barrel and chamber. First shot went off and clocked 1200fps. Second shot clocked 1010fps and the case separated. I am pretty sure I know what happened and need a few of you to chime in and tell me what I did wrong then roast me for doing something dumb.
Top round is loaded cartridge.
Middle is first round fired.
Bottom is second shot fired. As you can see, the neck and a good portion of the shoulder ended up in the barrel. The brass is a nice representation of the rifling
The load was 85gr of FFg, and 20 gr of Cream of Wheat under the RCBS 468-485 FN, all stuffed into converted MagTech 24ga shot shells. Let me know what you think.
I'd like to be able to throw out a disclaimer or excuse as to why I screwed this load up, but nothing creative comes to mind.
So, what I think happened is that the COW was below the shoulder and when I fired, the COW became a plug that ripped the case apart. Fortunately, since this was the first time loading for this, I only loaded five rounds. The converted shot shells have fairly thin walls and even 85grains of FFg leaves a ton of space in the brass.
COW was not the answer and I know better but I guess I just didn't give my load a sanity check.
Maybe one of these days when I have a few hundred extra dollars lying around I'll get a box of 20 Bertram cases. If someone has some 577/450 Bertram cases, I could trade a box of new .43 Spanish Bertram cases...