doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Does choke affect MV

I remember a chapter in "The American Shotgun" that presented data from a 1920-30's test by one of the big arms makers (Remington?) that showed increasing MV with increasing choke constiction. I also recall a discussion on said topic here. Does any one have a URL for this test data?

DDA

No shotgun citation from me, but it sounds like the venturi effect as applied to shotgun pellets. Yes, I know pellets are not a fluid, but they may behave in a somewhat manner when flowing through a constriction. Following is from Wikipedia, just because it was the first Google hit for "venturi effect:"

"The Venturi effect is a jet effect; as with a funnel the velocity of the fluid increases as the cross sectional area decreases, with the static pressure correspondingly decreasing. According to the laws governing fluid dynamics, a fluid's velocity must increase as it passes through a constriction to satisfy the principle of continuity, while its pressure must decrease to satisfy the principle of conservation of mechanical energy. Thus any gain in kinetic energy a fluid may accrue due to its increased velocity through a constriction is negated by a drop in pressure. An equation for the drop in pressure due to the Venturi effect may be derived from a combination of Bernoulli's principle and the continuity equation.
The limiting case of the Venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound. In choked flow the mass flow rate will not increase with a further decrease in the downstream pressure environment."

Any engineers out there to comment?

BTW, the speed of sound at sea level is listed as 1126 ft/s.

Here you go:

http://books.google.com/books?id=fYsoAAA...p;q&f=false

Should be simple enough to verify with a chronograph.

Pete