walt1980 Posted October 13, 2015 Report Share Posted October 13, 2015 Anyone know if the muzzle velocity is any different between a semi auto and an over and under? He thought maybe if the gas goes out the barrel vent it's less resistance so might be faster? Also when I was chatting to a mate he asked if an a400 with the kick off stock effects the velocity as well? Quote Link to comment Share on other sites More sharing options...
Savhmr Posted October 13, 2015 Report Share Posted October 13, 2015 Errrr...if gas is bled off for reloading, then barrel pressures will be less, so velocities I'd guess would be less and not more. Quote Link to comment Share on other sites More sharing options...
a303 Posted October 13, 2015 Report Share Posted October 13, 2015 Didn't Bob Brister cover this subject in his book. (Think that's his name) I'll check when I get in but the bottom line was it was such a minuscule amount it wasn't worth thinking about. Quote Link to comment Share on other sites More sharing options...
Harnser Posted October 13, 2015 Report Share Posted October 13, 2015 Self loaders are timed so that the action does not start to move until the shot and the pressure in the barrel has dropped and the shot has left the barrel . They work by using the latent gas left in the barrel . There would be no noticeable difference in muzzle velocity . Harnser Quote Link to comment Share on other sites More sharing options...
ChrisAsh Posted October 13, 2015 Report Share Posted October 13, 2015 Dont some do it on recoil Quote Link to comment Share on other sites More sharing options...
Savhmr Posted October 13, 2015 Report Share Posted October 13, 2015 So it's a non-issue and not worth worrying about. Better to just pick a cartridge that works well and forget all about the small differences that may or may not exist. Quote Link to comment Share on other sites More sharing options...
Harnser Posted October 13, 2015 Report Share Posted October 13, 2015 Dont some do it on recoil Yes they do . They are a different animal . Harnser Quote Link to comment Share on other sites More sharing options...
walt1980 Posted October 13, 2015 Author Report Share Posted October 13, 2015 It was just something that came up in conversation. Didn't think it'd make much difference, cheers peeps! Quote Link to comment Share on other sites More sharing options...
sportsbob Posted October 14, 2015 Report Share Posted October 14, 2015 Dont some do it on recoil Yes but the recoil happens after the shot has left the barrel. Quote Link to comment Share on other sites More sharing options...
neutron619 Posted October 14, 2015 Report Share Posted October 14, 2015 (edited) Yes but the recoil happens after the shot has left the barrel. The recoil happens immediately the wad and shot begin to move - it is the force opposing the force which accelerates them out of the barrel and begins at the instant that the powder starts to combust, producing the combustion gases which cause this acceleration. See Newton's third law. Edited October 14, 2015 by neutron619 Quote Link to comment Share on other sites More sharing options...
walt1980 Posted October 15, 2015 Author Report Share Posted October 15, 2015 So if the stock has a kick off thing the action will go backwards at the time of the bang? Surely the energy being used to move it backwards reduces the energy pushing the shot forwards? My mate said it'd be like an Olympic sprinter using starting blocks that moved backwards when you push on them?! Has anybody done a back to back test through a chrono?? Over and under Vs gas semi auto Vs semi with a kick off? Quote Link to comment Share on other sites More sharing options...
Harnser Posted October 15, 2015 Report Share Posted October 15, 2015 (edited) On the old recoil operated self loaders the barrel recoiled backwards and worked the action . These guns were timed so that the bolt could not open until the shot had left the barrel . Remember we are only talking milli seconds for the gun to ignite the powder and the shot to exit the barrel . If the bolt were open before the shot and wads left the barrel you would have massive pressure blowing out of the side of the bolt across your face . You would then instantly loose pressure in the barrel to have the shot drop out of the end of the barrel . If the barrel recoiled before the shot left then you would not be able to stay on target . It would be more like a flint lock gun . If you have access to a recoil operated self loader , stand it on the ground barrel up and push down on the barrel , you will see that the barrel will move back an inch or so against the main Spring pressure before the bolt starts to open . This is the guns timing. Harnser Edited October 15, 2015 by Harnser Quote Link to comment Share on other sites More sharing options...
sportsbob Posted October 15, 2015 Report Share Posted October 15, 2015 The recoil happens immediately the wad and shot begin to move - it is the force opposing the force which accelerates them out of the barrel and begins at the instant that the powder starts to combust, producing the combustion gases which cause this acceleration. See Newton's third law. Quite right you are, I was confusing recoil with muzzle flip caused by the escaping high pressure gasses from the end of the barell . Quote Link to comment Share on other sites More sharing options...
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