In truth, 100% of the recoil in a non- compensated, non braked firearm is caused by the unopposed pressure on the bolt face, one COULD graph the developement of instantanious recoil by looking at the pressure curve during ignition. Now the bullets friction against the walls of the bore actually serves to reduce recoil for a while, but it also serves to cause the pressure to spike higher. Whether these two factors equal out or not, well I would suspect not, the higher pressures would probably result in more felt recoil, by causing the recoil to be distributed over a shorter duration.

There was a statement early in this discussion which was false and I've not seen anyone correct it yet. The bullet and gasses "pushing" against the atmosphere does NOT contribute to recoil, if it did then rockets would not work in a vacuum. In fact the recoil of a rifle would be slightly MORE in a vacuum than in an atmosphere, since the muzzle velocity would be greater. It takes a lot of energy to compress to air in the barrel and get it out of the bullets way. This was one of the things shown by a test which was done firing 32 caliber rounds down a 120" barrel.

Wow! that made me dizzie!
So how would this relate to my pistol in .40S&W, I want less recoil, and you guys have my interest. However I am very new to reloading and ballistics etc, so please give this to me in english as to a good powder to use with a 155gr tmj in a Glock 23 .40 cal. to keep recoil minimal and learn good shootin without getting hammered.
Thanks very much!