The Firing Line Forums - View Single Post - Is the impact of being hit by a bullet the same as the recoil felt by the shooter?

shikijiyu · December 18, 2009, 11:18 AM

Wow. This is a better turnout than I had dreamed. Thanks everyone for pitching in. Here are some of the points, that in terms of my own argument with my potential future father in law, were very salient:

Theoretically, and at least initially, the answer is yes. Equal forces pushes in both directions.

Good points were made about energy loss during bullet flight from friction with the atmosphere, indicating that, to some extent, the bullet has less energy when it reaches the target. At first, I thought this might not be so relevant. How much energy could a bullet in flight really lose? The answer is related to the weight of the bullet, but the answer is potentially a LOT.

The counter point is that the mechanical parts in the firearm will also absorb some of this force – especially if the firearm is a semi auto . But even if not, stocks, grips, and even bolt housings and threading will absorb a small amount of force as the all move a tiny amount.

There are several comments (and a mention of a thought experiment) that I think give me some serious “ammunition” for the next time we get into this:

rsgraebert: “The firearm weighs an order of magnitude more than the bullet.”

wpcexpert: “Go to a recoil calculator like the one found here:http://www.handloads.com/calc/recoil.asp”

I looked at the calculator, realized an important aspect of the calculation was the weight of the firearm, was thinking about rsgraebert’s magnitude comment, and I came up with the following thought experiment:

If a ruger 10/22 weighs five pounds, that’s actually 35,000 grains. That would be THREE orders of magnitude greater than the weight of a standard 22lr round.

So the thought experiment is this:

Imagine if you took your bullet and made it a THOUSAND times heavier before you shot it. Imagine, if instead of a bullet, what you were firing was the rifle itself. If the force of the propellant was used to accelerate something the same size and weight as the rifle, the effect when it hit your target would probably NOT be particularly brutal. It might just be (ignoring atmospheric friction and mechanical force absorption on the part of the firing rifle) about the same impact as the recoil experienced by the shooter.

Theoretically, the same concept could be extended to ANY firearm. The subjective experience of recoil is less for rifles because of their greater weight than firearms (assuming the same caliber cartridge). If you were to take a .40 pistol, and use it to shoot a round that was the same size and weight as the pistol (physically impossible – I know, this is just theoretical), then I would wager that the impact of that pistol sized round hitting a target would be very comparable to the force felt when firing said pistol (although the feeling of being struck by something, compared to holding something that jerks, would of course be different).

Anyway – just my two cents, given all the great feedback.

December 18, 2009, 11:18 AM	#45
shikijiyu Junior Member Join Date: December 17, 2009 Location: Albuquerque Posts: 4	Wow. This is a better turnout than I had dreamed. Thanks everyone for pitching in. Here are some of the points, that in terms of my own argument with my potential future father in law, were very salient: Theoretically, and at least initially, the answer is yes. Equal forces pushes in both directions. Good points were made about energy loss during bullet flight from friction with the atmosphere, indicating that, to some extent, the bullet has less energy when it reaches the target. At first, I thought this might not be so relevant. How much energy could a bullet in flight really lose? The answer is related to the weight of the bullet, but the answer is potentially a LOT. The counter point is that the mechanical parts in the firearm will also absorb some of this force – especially if the firearm is a semi auto . But even if not, stocks, grips, and even bolt housings and threading will absorb a small amount of force as the all move a tiny amount. There are several comments (and a mention of a thought experiment) that I think give me some serious “ammunition” for the next time we get into this: rsgraebert: “The firearm weighs an order of magnitude more than the bullet.” wpcexpert: “Go to a recoil calculator like the one found here:http://www.handloads.com/calc/recoil.asp” I looked at the calculator, realized an important aspect of the calculation was the weight of the firearm, was thinking about rsgraebert’s magnitude comment, and I came up with the following thought experiment: If a ruger 10/22 weighs five pounds, that’s actually 35,000 grains. That would be THREE orders of magnitude greater than the weight of a standard 22lr round. So the thought experiment is this: Imagine if you took your bullet and made it a THOUSAND times heavier before you shot it. Imagine, if instead of a bullet, what you were firing was the rifle itself. If the force of the propellant was used to accelerate something the same size and weight as the rifle, the effect when it hit your target would probably NOT be particularly brutal. It might just be (ignoring atmospheric friction and mechanical force absorption on the part of the firing rifle) about the same impact as the recoil experienced by the shooter. Theoretically, the same concept could be extended to ANY firearm. The subjective experience of recoil is less for rifles because of their greater weight than firearms (assuming the same caliber cartridge). If you were to take a .40 pistol, and use it to shoot a round that was the same size and weight as the pistol (physically impossible – I know, this is just theoretical), then I would wager that the impact of that pistol sized round hitting a target would be very comparable to the force felt when firing said pistol (although the feeling of being struck by something, compared to holding something that jerks, would of course be different). Anyway – just my two cents, given all the great feedback.