How much energy is my rifle producing?

Question

I designed a single-shot homemade railgun that fires copper ball bearings. After test firing it a bunch of times I tested it on a common tree squirrel. When he was on the ground I fired a shot at him and when I heard the bb hit him, his body was lifted off the ground and thrown almost 5 feet.

I do not have a chronometer (can't afford it yet) but I'm thinking my muzzle velocity must be higher than 2000 fps. I was wondering if anyone knows how many ft/lbs are required to "lift" a squirrel off the ground.

Answer 1

To find kenetic energy, you multiply the weight of the projectile (in grains) by the velocity (in feet per second) squared and divide by 450,240. This will give you ft/lbs of kinetic energy. The reaction of the squirrel was probably muscular reaction, not the impact of the BB.

Answer 2

A chronograph costs less than $100. No amateur ballistician should be without one. Without knowing the mass of the squirrel, where it was perched at the time, if the projectile remained in the squirrel, or if it penetrated it through-and-through, and the mass of the projectile fired, it would be next to impossible to accurately determine the KE or velocity of the projectile fired.

For a better (well, more interesting) test, get a bunch of old newspapers or telephone books. Soak then in water overnight, and then line them up until you have a backstop six feet deep. Then fire, find how deeply the projectile penetrated, and then consult the second link. A .45-70 firing a 450 grain solid copper bullet at 1713 ft/sec penetrates 47 inches. Which is great until you consider that a lowly factory .45 Colt load throwing a 250 grain bullet at a measly 950 ft/sec penetrates 21 inches in the same medium . . . almost half the penetration with a sixth of the KE.

Answer 3

Did ya cook him yet? LOL


SQUIRREL STEW

Ingredients
2 squirrels cleaned and cut into pieces
1/4 cup flour
1 teaspoon salt
1/2 teaspoon pepper
2 tablespoons olive oil
3 cloves garlic, minced
2 large onions, chopped
4 cups water
4 beef bouillon cubes
1 large potato cubed
2 large carrots, diced
2 ribs celery, diced
2 cups frozen lima beans
2 14 1/2 ounce cans diced tomatoes
2 cups frozen corn kernels
1 teaspoon Worcestershire sauce
1 1/2 teaspoons sugar
3 tablespoons flour
Few squirts of Tabasco

Directions
Dredge squirrel in flour, salt and pepper
Heat olive oil and garlic in large Dutch oven and brown squirrel
Add onions and cook until soft
Add water, bouillon cubes, potato, carrots and celery
Cover and simmer for 1 hour
Add lima beans, tomatoes, corn, Worcestershire and sugar
Cover and simmer for 30 minutes
Mix 3 tablespoons flour with 1/2 cup cold water, stirring until smooth
Add to stew and simmer until slightly thickened
Season to taste with salt and pepper

Answer 4

Honestly i couldn't tell ya.. but if you know the weight of the ball bearing and velocity this calculator will help.

http://www.firearmexpertwitness.com/customguns/calcnrg.html