Dear Maraki and others, Thanks for the info. I do use a chronograph and only slow burning powders, including R22 and IMR 4831. I have not exceeded 2,300 feet per second and my best load produces about 2,250 in the left barrel and a little less than 2,200 in the right barrel, well under the 2,400 advertised. So I don't think pressure is the problem. I will check for drag marks. Thanks again, Keith

PS Is it common for doubles to be proof marked for one load and regulated for another? My Jeffery is proof-marked 42 grains Cordite 300 Max, but the barrels are inscribed "for 250 grain bullets."