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Comment by wizdumb | Hacker News Reader

I wrote a long-form article about an experiment that I conducted this summer to explore the question of whether or not recoil-management techniques have an effect on muzzle velocity. It involved a bit of data science (Python, pandas, plotly), some hardware (arduino, 3d printing), and math (LaTeX). I hope that this content is high quality enough to justify the time you spend reading it, and how much time it took me to create it!

I’d love to hear your feedback and answer any questions!

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That's a great article even if the results were a little inconclusive due to unanticipated uncontrolled factors (bullet length). I'm just happy to see someone showing how the worlds of firearms and hobbyist hacking can fit together.

It's unfortunate that everything related to firearms is now viewed as political. There are just so many interesting things unique to thos subject matter that inquisitive and mechanically inclined people, like those on HN, are missing out on.

I think Destin Sandlin, of the youtube channel SmarterEveryDay does a good job of having firearms related physics videos (in addition to other science, physics and space videos) that are non-political.

Thank you for reading it and sharing your thoughts!

I'm just here to learn and share. Hopefully this will help towards breaking down some negative stereotypes about a fun an interesting hobby!

Very interesting article! One comment - when the firing pin is released and moves forward, the gun recoils backwards slightly to conserve momentum.

I suspect what you saw was the sudden release of the couple of pounds of rearward trigger pressure causing the gun to move forward shortly before the pressure buildup and recoil drove it backwards. That would swamp any small recoil associated with the firing pin.

Great feedback! It's definitely true that I need to do some more research on this particular aspect. My trigger is set to 1 pound before it breaks (some folks set theirs to 2 oz!) Pulling it gently, like you're supposed to, shouldnt generate the same acceleration as if you were to "slap" it (which is a bad practice for accuracy and precision).

It may require faster data acquisition, so I hope that folks will contribute to the accelerometer project that I open-sourced to make that possible! https://github.com/ammolytics/experiments/tree/master/recoil...

Thanks again!

I'm not sure if you are correctly interpreting wrycoder's explanation. Or maybe I'm not, but I think his point is not about how fast the trigger is pulled, but about what happens as right after the trigger mechanism releases, independently of proper technique trigger finger technique.

Just before the trigger releases, you are pulling back with 1 lb of force on the trigger, and to maintain aim, are pushing forward with 1 lb of force on the butt (likely with your shoulder). When the trigger releases, suddenly there is no more force being applied by your trigger finger, but the same amount being applied by your shoulder. In response, the gun starts moving forward. It keeps moving until the trigger bottoms out and the force from your finger stops the forward progress, or until the recoil from the acceleration of the bullet begins.

I'm not sure he's right, but I think this is what he's saying, and I think it fits what you measured. I am confused though how the gun can move forward in the "preloaded" case. Isn't the gun already pushed forward as far as it can go against something incompressible? If so, how does it accelerate forward?

The easy way to control for this is to run the same measurements with a spent cartridge chambered.

I enjoyed the article, and you did a great job presenting the data in a clear way. Whats the name for the type of graph that looks like a box and whisker plot inside of a probability distribution?

Thank you! Yes, as merlincorey correctly mentioned, they're called "violin plots".

Are you talking about the Violin plots?

yes, thanks

If the violin plots don't do it for you I recommend Georgia O'Keefe paintings as an alternative.

This is cool. When looking to muzzle velocity, did you measure the diameter / weight / length of the bullets? It seems there could be some interesting effects there.

1. Interference with the rifle barrel 2. Interference with the shell casing (is there a measure of how tight a shell fits the bullet that changes the velocity / is more interference fit good?) 3. do slight variations in diameter or weight matter more?

Great work!

Thank you! As I mentioned in the Next Steps section of the article, measuring the effects of bullet sorting by weight & length is definitely a topic for a future article.

I really enjoyed this. I'm not a shooter, but it's hard not to be excited by the analysis you've done. I learned a ton.

Thank you so much, this really means a lot to me!

Yes. Uncontrolled recoil has effect. It is a physics problem most undergraduates do (throw something heavy on ice, two bodies move in opposite directions, energy spent sliding the thrower is removed from the projectile due to conservation of energy, etc). The question is not whether it does, but to what degree?

It looks like youre measuring muzzle velocity with a device mounted to the barrel. If that's true, i suspect it almost entirely negates the difference you are looking for because the rifle recoiling adds perceived muzzle velocity that the target (and the rest of us) do not experience.

Thanks for the feedback! I've heard this suggestion a few times, and it is an interesting thought. I believe that the calculations I did which show that the bullet has left long before the rifle moves under recoil contradicts this.

That said, I'm more interested in the truth than who is right or wrong. I've open sourced all of my data and want others to try this experiment for themselves and share their results rather than rely on me as a source-of-truth!

Excellent article, I learned a few things.

Thank you for taking the time to read it!

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