>>thanks for clearing that up. I've not gotten a chance to shoot a .40, but I wonder if it may also have to do with the relative weights of the guns involved.<< I think it is internal ballistics -- 40S&W operates at higher pressure than 45 ACP, so it kicks the slide back harder and faster than a 45 ACP does.

The .40 does operate at much higher pressures than the .45 acp. This leads to higher Bolt Thrust. Bolt Thrust = PSI X case head area. This, as you said, leads to higher slide velocities and more ware on the pistol. If you reload the higher operating pressure is also a factor as case life is much shorter. Also recoil springs will need to be checked and replaced more often with a higher Bolt Thrust. Bb

I often hear it said that while some rounds will result in fast, sharp recoil, others will have more of a slow push. Personally, I really don't believe in it, as the recoil is still going so fast either way, does a bullet going 600m's compared to 1000m's really make a difference? The best I have done to compare to it, was a while back when I had the chance to fire various weapons. I fired an H&K51 in 5.56mm, and then straight after fired a No.5 Jungle carbine in .303, where the expected strong push back was replaced by a mule kicking me in the shoulder. The only reason I fired 20 rounds was because I didn't want to be seen giving up. ;) so I say the "slow push" thing is a myth.

Yimmy, I can't tell you that what you experienced with those rifles was not as you said. But as far as autoloading pistols go, based on my experiences I have to disagree. Whether it's internal pressure, muzzle velocity, the weight of the weapon, or some combination of all three; a Glock 22/.40 S&W has more "snap" (I don't know how else to describe it) than a Glock 23/.45 ACP. So far I haven't encountered a single person who has fired both weapons that has not said the same. Maybe they exist, but I haven't met them yet; and I know lots of people who have fired both pistols. Horsesoldier and Bigbro, thanks for the explainations.

Yimmy, total recoil energy my be the same for a given ejecta mass and velocity however that is a sum of the energy. This is an area under a curve. The peak acceleration to the weapon will change due to the pressure curve of the cartige and the ratio of ejecta mass to velocity. The peak acceleration is what makes for the difference in preceived recoil. Shoot a 3 1/2 " 12 gau. mag and a .338 win. mag. push vs. slap. You well have a mark on your sholder with both however. Bb

Bigbro (chuckling) that last post was impressive but it made my head hurt! You need to drop by snipercentral.com, you could have a great conversation with a guy who posts there as madgunsmith. I've seen Yimmy over there and I'm there too. I use another nickname over there but I doubt I'm hard to figure out!

Semi Autos in a given cartige will have less preceived recoil than a fixed breach weapon. Take a .308 winchester bolt gun and x semi in 7.62 X 51 nato. fire the same ammo in each and adjust the weight of both weapons to equal each other . the bolt gun will seem to kick harder. Stock design, you should know all about this in altering felt recoil. I was on a hunting trip a few years ago in Canada. My guide was not happy at first when I showed up with my .338. He was concered about me flinching. of 12 people in camp I was the only one to take two animals with a total of two shots. The longest shot was only about 250 meters. Recoil tolerance is a highly personal thing and should govern the largest weapon that a person takes out. The move to 5.56mm was a good one in terms of over all marksmanship as you have less than half the recoil of the .303 or 7.62 x 51. As a note, when firing multiple weapons at a range always start with the one with the heaviest recoil. Bb

Sorry I get a little tooooo into things sometimes. I have not heard of snipercentral before. May be I will check it out if you think that it is a good site. thanks Bb

Heh, I didn't know you posted at SC longrifle. It is a great forum, despite my clashes of opinions with the locals. :D Whatis your username there, if you dont mind my asking? I sometimes feel my always using the same name puts me at a disadvantage!

My username at snipercentral is classified info Yimmy! LOL! In all seriousness though, see if you can figure me out. I doubt I'm that difficult to spot.