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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Why I think the Satterlee and Audette Ladder Tests Work and Why-- You Decide!
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<blockquote data-quote="Veteran" data-source="post: 2438239" data-attributes="member: 118038"><p>Yes, I was referring to the pressure profile in the can as the bullet pushes and compresses air and possibly some gas from the explosion that leaks by the bullet in the land grooves, into the can vs. just pushing that on out the barrel into atmospheric 14.7 psig.</p><p></p><p>The pressure in the can especially in a longer bbl. has to be a bit higher than 14.7 psig atmospheric pressure. It just has to be mechanically, therefore it is exerting some amount of back pressure on the bullet before exit. </p><p></p><p>If you put a filter on the end of s garden hose what happens?</p><p></p><p>Flow rate slows due to back pressure. So I have no idea whether we can measure backpressure due to a can or how much it may slow muzzle velocity but I think it does. The only caveat I can think of is if you have a long bbl and a very slow powder, then the pressure curve or burn rate curve may have time to more fully develop giving added force from the chamber side of the explosion and increasing velocity that way. It would be similar to deeper bullet seating w crimps on a slow powder and long bbl. </p><p></p><p>So, perhaps there are boundary conditions where it can go both ways? </p><p></p><p>Short bbls. with fast powders, its more likely to slow the bullet because there is no time for the burn curve to do anything more than its already doing....Burn curve = proxy for pressure curve or profile in the bbl.</p><p></p><p>In a long bbl w slow powder, maybe the velocity can increase because the back pressure delays bullet exit time in milli seconds that allows for a more complete powder burn to occur equals more force on chamber side of the bullet.</p><p></p><p>Gonna have to read up on cans. But I do know its proven they will change bbl. harmonics.....mainly I think due to weight and sin wave interactions along the bbl. There may also be a delayed bullet exit time as postulsted above causing the shift in POI and different bullet groups or MOA with and without a can.</p></blockquote><p></p>
[QUOTE="Veteran, post: 2438239, member: 118038"] Yes, I was referring to the pressure profile in the can as the bullet pushes and compresses air and possibly some gas from the explosion that leaks by the bullet in the land grooves, into the can vs. just pushing that on out the barrel into atmospheric 14.7 psig. The pressure in the can especially in a longer bbl. has to be a bit higher than 14.7 psig atmospheric pressure. It just has to be mechanically, therefore it is exerting some amount of back pressure on the bullet before exit. If you put a filter on the end of s garden hose what happens? Flow rate slows due to back pressure. So I have no idea whether we can measure backpressure due to a can or how much it may slow muzzle velocity but I think it does. The only caveat I can think of is if you have a long bbl and a very slow powder, then the pressure curve or burn rate curve may have time to more fully develop giving added force from the chamber side of the explosion and increasing velocity that way. It would be similar to deeper bullet seating w crimps on a slow powder and long bbl. So, perhaps there are boundary conditions where it can go both ways? Short bbls. with fast powders, its more likely to slow the bullet because there is no time for the burn curve to do anything more than its already doing....Burn curve = proxy for pressure curve or profile in the bbl. In a long bbl w slow powder, maybe the velocity can increase because the back pressure delays bullet exit time in milli seconds that allows for a more complete powder burn to occur equals more force on chamber side of the bullet. Gonna have to read up on cans. But I do know its proven they will change bbl. harmonics.....mainly I think due to weight and sin wave interactions along the bbl. There may also be a delayed bullet exit time as postulsted above causing the shift in POI and different bullet groups or MOA with and without a can. [/QUOTE]
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Why I think the Satterlee and Audette Ladder Tests Work and Why-- You Decide!
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