Early Pressures vs Modern Pressures!

March 29, 2019

Somewhat of a conclusion to my thinking. Sometimes the best way to get answers is to post conflicting information rather than simply asking a question.

So...... Recap In 1894 Winchester first offered their smokeless powder for the 44–40. The new boxes had a Red label specifically marked for the Winchester 73 but NOT FOR PISTOLS. This new smokeless powder gave velocities to 1,300fps but produced high pressures. Dupont #2 powder was used. Dupont #2 was quickly replaced with Sharpshooter which was designed to be used in black powder firearms and produced less chamber pressures than black powder. Sharpshooter was used all the way up to 1948. However, Dupont #2 was not discontinued until 1926. In 1913 SR80 (Sporting Rifle 80) was introduced. SR80 was also used for High Velocity rounds in the 44–40. Published loads of 18gr of SR80 with a 200gr JSP produced 1,625fps. Even today, SAAMI list the 44–40 as a rifle cartridge.

Black Powder Testings I have tested 40gr/w of Swiss FFG black powder with a .18″-.20″ compression with original early semi-balloonhead unheadstamped 1880’s brass and produced 1,373fps @ 14,285psi. Same loads using Goex FFG produced 1,356fps @ 12,648psi. The same loads using Starline Brass with .21″ compression produced only 10,000psi. The same loads used in post 1890’s semi-balloonhead mixed headstamped cases produced 10,500psi.

Early Smokeless Powder Thoughts I am lead to believe that early 44–40 black powder cartridges produced around 14,000psi while early Dupont #2 smokeless powder produced even higher pressures which is why they should not be used in early black powder frame revolvers. I am lead to believe that when Winchester switched to Sharpshooter powder, the pressures dropped to the 11,000psi mark and is what set the standards of today. My testings have been consistent but I can not dig out actual historical pressures. I doubt I ever will.

My replicated 1,600fps High Velocity loads produce in the 18,000psi range which leads me to believe that this would be close to 22,000cup according to Lyman’s 49th handloading manuals load data and Winchester HV data.

Sounds reasonable but who knows...???