Lane

There are people who have already done this. I'm quoting some other sources for sure. https://archive.org/details/RifleAccuracyFactsFullV1.0FirstFullScan

Do you want a strain gauge to use as a mic to attach to your lower? Use the one, or a very similar one; that someone uses for the strain gauge on the chamber. You can collect audio data with any PC sound card, or tablet, or cell phone. If you have access to audio recording equipment it's a lot higher resolution. But again; you don't care about more than ms resolution already, so regular CD quality or DAT is fine if that's all you get.

Oh. So you overdrove the input. No problem at all. Use a different Mic. You'll certainly need adjust for the violence that happens inside and outside of a gun. The conductive mic on the lower is probably the starting point. Use negative gain.

Are you still nipping his fins? You better watch yourself. I'd rather not get the full weight of that gorilla.

Which one? It's really all a matter of what data you want. A triggered recording of all of the above would be quite simple. Where do you want a strain gauge? They can be placed almost anywhere. The standard measure is over the chamber to measure the pressure inside the cartridge. That's tough in an AR with the barrel nut in place. To modify your own gun you might need to replace that (break perfect timing), or use a sub-standard placement. They can also be placed on the upper, or the barrel; or even the lower. Record the sound at the highest sample rate possible. Record the Gyro data from the barrel and acceleration data on the upper receiver. Where have I heard of this before? Anyway. A quick an dirty would be an old cell phone. Preferably the lightest weight model you can find. Don't know what kind of Go Pro has high speed video recording these days. But that would be a good start as well. Seriously. An audio recording from your Phone or with a Microphone attached to the lower would give you almost 100% of the data you care about up front. You can add more when you find a hole.

I don't want to thank the wrong person. But @SimonSays was around back then. I can't find it in the search at the moment... There's a LOT of good reads to add on. TONS of research from the turn of the previous century is GOLD. I wouldn't ONLY stick to modern literature. You'd all likely be shocked at how much we knew back in 1905-ish.

To be frank. You can measure that with a microphone attached to your gun. But yes. There is certainly some research in that area. Even a high speed video camera would do a lot (since it has synced audio too). There are plenty of slow motion youTube videos even. Since there are so many variables (including part fit, and absolute friction (the sum of all those)); you're not going to get a perfect fit calculator. Too many other factors too. Bullet fit in the barrel (amount of blow by), twist, barrel profile, caliber, amount of blow by in the chamber as the cartridge seals), etc. etc etc. The good part is, the timing on the bolt side is so LATE in the process you can "hear it all" in your own gun. If you want to add and IMU (gyro/accelerometer) that could help if you had some mechanical issues too... But I still don't know what you don't know, or what you want to know.

Did we link that one before? I think not... http://www.the-long-family.com/optimal barrel time.htm http://www.the-long-family.com/OBT_paper.htm https://thebloke.co.nz/lab-radar-obt-testing/#:~:text=OBT – Optimal Barrel Time,pressure wave) down the barrel. https://pierrevanderwalt.com/obt-calculator/ Beware. I'm a firm believer that all calculators are going to be a "bit" off. By a few kernels of powder, really depending on the actual barrel you have.... But that's just my personal "feeling" on the matter. I've yet to compile proof either way.

I could link it if I had to try. You can find a discussion searching this forum if you want to see my previous reactions. I know there is a way to calculate them with QuickLoad (software). Optimum Barrel Time. Refers to the the flex of the barrel, and the absolute moment in time that the bullet exits the tip.

There are others around here... But you'll need to come back with a list of new questions. There is a TON of research on both bolt, and gas operated guns. Focus those questions deeper. Try to find a niche that needs an explaination. Your initial questions about speed can be informed by reading about OBT. Your questions about one hole will at least partially be explained by the Houston warehouse experiments.

He has a relative contribution, or 10; or 100. But you'll have to read first... I know you didn't read those in full; because you didn't reply with a whole string of "What about....." questions. But yes. At the core of it. The initial question is about gas operation which is 100% internal ballistics minus the moments after the bullet left the barrel. And while there is still internal "activity" happening after the bullet is gone; the bullet has left the building before the action cycles. So; what do you really CARE to know about?

I'm not trying to punk you. I read it myself. And it spurred a whole lot more thinking. In general. It's trivial to hit 1 hole every time at 100 meters. Or even 200 meters.

Correct. You only shoot one shot at a time... Read that stuff.

I'm going to have to LOL you on this too. The reason is that gas autoloaders aren't going to significantly change the physics you were asking about in terms of ONE HOLE. And you can surely adjust one way or the other if you missed the ONE HOLE accuracy.

YEAH!!!! That one too. You can read about O.B.T. after that. You'll need both. In all seriousness. There is a TON of research beyond that; but both of those are a super jumping off point. Frankly; I'm suspicious about the barrel length variable in OBT. But the general theory is absolutely correct (pretty sure the basic formula is still wrong though).

Don't need a copy of either, and I don't care about them. Wana see my FAA license too? LOL. I think we need a new waterboarding for science thread.

Well you might not care as much about internal ballistics as you think you do. I've been pointed here in the past. But read up on OBT. Let me know what you think of that theory... That should solve most of your problems besides the smooth cycling.

This is what broke me too. Distance shooting would be a dream. It's trivial to build a rifle that's accurate for 100 meters (hunting). Some of us rarely get a chance to reach out further. Once that sinks in; it's easy to become curious about the other nuances at play. It's sort of the best one can do in terms of preparing for that "one day" when they'll be allowed to shoot at long range. But at the surface. It sure would be "neat" to have a calculator for the gas system vs. recoil. Spring constants are VERY easy to calculate (had to do that in university physics labs). Those other variables could be determined easily enough with some data collection (and I mean A LOT of data collection)...

This is about what I expected intuitively. One could load blanks, and super light projectiles to mess around with this. Not really sure off hand what kind of recording equipment would be useful though. Really depends what you are most curious about in this situation. Design an experiment. Execute. Talk about it. For some people, that's daily life... Don't be afraid to be curious. Try to focus your questions.

I know I will!

Speed of sound is 330m/s, at standard temperature and pressure. It changes with temperature, and; pressure as well. Your ears are obviously useless inside the barrel, but physics still applies. What I was trying to figure out when I first read the initial question; "is this actually a plasma, and not a gas at those pressures"? That changes the game 100% (and from your deduction that "it's all pressure" I still think that's entirely possible).

I disagree. In terms of internal ballistics (before the bullet leaves the barrel); the speed of sound is the same as the flame velocity inside the barrel up to the bullet passing the gas port. (pretty sure, feel free to correct me if I'm wrong here)... This is an interesting rag chew regardless of whether any of us fully understand the physics behind the gas system in that amount of depth. I could spam this thread with a ton of research papers, but even then; we would all have to read and understand them to be on the same page. High pressure is a very interesting field of study in so many disciplines; including internal ballistics. While reading some older research I was totally SHOCKED that the author used a hydraulic system to simulate case pressure to test a strain gauge attached to the outside of his rifle chamber. He wanted to calibrate it to a known pressure value, so he used what amounts to the brake system on a car to pressurize a modified brass cartridge inside the gun...

I'm not exactly afraid to move... I've moved around before; and it was always at a whim. There was some tipping point, and it was time to go. Maybe I packed up in 8 hours and bolted, maybe I had a few weeks. Every time it was always a quick, but surgical operation. I lost a lot of belongings in the process for various reasons (couldn't pack everything in one vehicles, sold stuff to fund something, etc.). Also lived the homeless life here and there; and always with a car. So couch surfing, sleeping in my car, camping; whatever it takes to make it happen. I'd rather hold on tight when I'm stable, until I just can't take it anymore. I recently did the math, and even a trunk load of just guns will weigh down my suspension pretty good. Not to mention all the tooling I would "like" to take with them...

You and me both brother. I'm really not sure what color any state will be this year... It's NOT going to be the same as 2016, that is for damn sure! I don't talk much about what I do (it sounds kind of pretentious); but I can work out of the trunk of my car if need be, or any old hole in the ground. Just keeping my ear to the train tracks these days; wondering what happens next.

Was personally intrigued when I read the original question... I had to google the speed of sound vs. temperature to refresh my memory. I still don't know how the gas pressure comes in to play though; I assume the speed of sound is changed by that as well? Further; since it's not just "gas", a flame front moving through the barrel also going to change things a bit. Having experimented with bags full of oxy-hydrogen, I can say it's likely that the flame velocity is different than the speed of sound to begin with. I'll keep a curious eye on this thread.