I was shooting my brass frame remington last weekend and was having a very strange problem. My load was 25 grains (volume) of American Pioneer fffg substitute. I was using a wonderwad for the first time, and .454 round balls which I normally use. I was also using Remington No 10 caps.
Here's what happened. I was shooting at about 35 yards and was not getting the accuracy I am used to. Also, a few times I would fire and there would be enough pressure and flash coming out of the nipple to force the hammer back and advance the cylinder a little. It didn't advance enough to cock it or anything, but it would advance enough to move the just fired chamber out of line with the bore.
I have always heard that the American Pioneer powder is actually weaker than fffg black. I was shooting the same volume that I would normally shoot with goex, but I was getting this freaky high pressure like activity. Could the wonderwads be contributing to the high pressure? Could it be that the flask was almost empty and only the fine grains remained? Could it be that the nipples have been enlarged by so much shooting and now allow too much fire through? I think I am due for a new set of nipples anyways, so I might as well try that while I am waiting for advice. Thanks in advance.