How to determine Foot poundage.

[tikkapaul]

I seem to recall way back when that to find the foot poundage of an air pistol or air rifle there was a gadget, which looked like a metal quadrant on a stand, this had if memory serves me correctly two pendulums , when placed,, a short distance down range the object was to hit a paddle on one of them, this swung the pendulum initiating the second pendulum to swing on impact.
On the quadrant which was calibrated the second pendulum would stay at its most forward position , and the one that was hit by the pellet would return to its original position thus leaving a reading on the pendulum giving the foot poundage of the chosen weapon, am I correct and are these gadgets still around or does one now get the desired info from a chronograph? .

[Turnup]

Google "Ballistic Pendulum". Was a time when this was the only way, but most people find electronic chronographs easier to use and more accurate these days.

[Benelli B76]

Also if you have the speed and weight of pellet there are loads of apps for phone or computer that do instant calculation for you if equipment does not.

Baz

[airgunnut]

Speed of the pellet in feet per second, times speed of the pellet in feet per seconds, times pellet weight in grains, divide by 450240. Simples

[tinbum]

Speed of the pellet in feet per second, times speed of the pellet in feet per seconds, times pellet weight in grains, divide by 450240. Simples

Where 450240 is twice the gravity constant multiplied by grains per lb. (7000)
You can change the constant accordingly if you weight shot in ounces or lbs.
Another interesting number is 671. Any object travelling at 671fps has a ft/lb power the same as its weight in grains. Ie a 15.6gr AA pellet at 671 is running at 15.6 ft/lb. an 8.4gr at 8.4 ft/lb etc.
so a 5lb cannon ball at 671fps is a whopping 35000 ft/lb, but it will still have the same basic trajectory as the .177 8.4gr pellet.

[harry mac]

so a 5lb cannon ball at 671fps is a whopping 35000 ft/lb, but it will still have the same basic trajectory as the .177 8.4gr pellet.

Ah, but the .177 pellet is no good for bouncing through massed ranks of Frenchmen

[MikB]

Where 450240 is twice the gravity constant multiplied by grains per lb. (7000)
You can change the constant accordingly if you weight shot in ounces or lbs.
Another interesting number is 671. Any object travelling at 671fps has a ft/lb power the same as its weight in grains. Ie a 15.6gr AA pellet at 671 is running at 15.6 ft/lb. an 8.4gr at 8.4 ft/lb etc.
so a 5lb cannon ball at 671fps is a whopping 35000 ft/lb, but it will still have the same basic trajectory as the .177 8.4gr pellet.

I think the British, as distinct from the American Standard for g results in a divisor of 450436.68 .

The 5lb cannon ball (and who ever used a 5 -pounder? ) won't have the same trajectory as any airgun pellet because there's a helluva lot more grains per square unit of cross section in the 5lb ball, so it'll retain velocity much better. You'd probably start to notice the difference within 50 yards or so.