Multi-Stage Delayed Blowback

[Sam Cade]

The MG will have mixed mode firing, firing from closed bolt in semi and open in full auto, like the M60.

M60 is open bolt only.

I would appreciate a mod to clean up the side talk in this thread too, please.

ehhh? What side talk?

The long stroke in MGs is cliched

Is the wheel cliché?
Designing for novelty is a bad idea.

and direct impingement, well lets just put it bluntly: I hate the stoner system.

That is illogical.

 

[Justin]

and direct impingement, well lets just put it bluntly: I hate the stoner system.

What actual hands-on experience do you have with the Stoner-designed direct-impingement system?

 

[Dreamcast270mhz]

The M41 Johnson was what I was referring to for mixed mode firing, my bad.

I chose delayed blowback because I have a lot of respect for the CETME and G3, both in military forms are really nice rifles with good accuracy and nice ergonomics. I also would love to own a FAMAS, one day maybe I will.

I really wish people would shut up about the blasted Blish Lock, it has nothing to do with this design. The main application I see this is a partial replacement for general purpose mgs in infantry support versions, where something like the FN Minimi does suppressing fire at close range, and this is used for supporting marksman and EBR bearing units, where belt feed is impractical.

 

[Sam Cade]

What actual hands-on experience do you have with the Stoner-designed direct-impingement system?

That is a durn good question.

Will the OP answer?

 

[45_auto]

Let me make myself clear: This is Delayed blowback, in which there is the bolt mass, spring pressure, toggle system (2 of them) not to mention the toggle springs, which can be much stiffer than the main return spring.

What delays it?

You have no mechanical means of delaying the unlocking of your breech. All you have are springs and the mass of your recoiling parts.

If you get someone capable of doing an actual analysis you'll find out relatively quickly that at rifle power levels the spring force required to delay the breech opening long enough for the pressure to drop to usable levels (bullet exits the barrel) will be so high that the bolt cannot recoil far enough to extract the fired case.

That's why every other successful high power blowback system ever fielded uses some form of mechanical locking (or bolt inertia in the case of the previously discussed Oerlikon).

Nothing wrong with dreaming, but it helps to mix a little reality in every so often. Do a scale drawing of your system and get someone to analyze the time scales and forces based on the pressure of the cartridge you propose to use. I get the impression that you have no background at all in basic physics or mechanics and are incapable of doing an analysis yourself.

Do you have any idea how long it takes a .30 caliber bullet to exit a 16" barrel? Can you figure out how much spring force it will take to hold a bolt of a given mass closed (not really closed, but you'll have to decide how far back it can move and still hold chamber pressure and call that closed). You'll need to calculate the acceleration of the bolt to figure out how long it'll take it to move the minimum distance you decide until the bullet leaves the barrel.

The toggles in your system as currently proposed do nothing to delay blowback, they are just a lever to amplify spring force. For example, a 100 lb per inch spring on a toggle with a 10:1 moment arm is the equivalent of a 1000 lb per inch linear spring. You can accomplish the same thing with either spring, each one will slow the bolt down equally. Probably easier to package the spring loaded lever, but you can always just wrap the linear spring around the barrel (like an Oerlikon). In neither case is there any mechanical method of delaying blowback of the bolt. Once you've calculated the spring force required, you can figure out how to best package it.

 

[rcmodel]

What is the point anyway?

Every major power in the world has long since settled on gas-operated locked breach system of some sort to be the cheapest, lightest, & most reliable method of building rifle caliber weapons.

You ain't gonna change anyones mind now.

rc

 

[Dreamcast270mhz]

I have plenty of friends with AR variants, two of which who have short stroke versions. They all spent in excess of 1k for the gun, accessories and such and my father's $500 Mini-14 shoots just as well if not better (it is a 2008 with forged barrel).

One of them has had his for a year and has went to the range at total of 39 times, and has broken his extractor 3 times. He uses brass ammo only, and reloads until the brass is no good. He also reports he is getting a short stroke upper, after shooting the short stroke AR-10 owned by my friend who really likes it because it stays a lot cleaner than his previous Bushmaster upper.

I'm not changing anyones mind, gas operation has its place. Look at the MG3, it is not long stroke and is used by many countries.

The toggles delay the breech. Did you even read my previous posts? Look at the Pedersen operation or Scharzwalose, both use a toggle system.

I'm not a math person by any means, all I do is design concepts and such. In fact, at my college we adopted a computer security system I aided in designing.

 

[Sam Cade]

I have plenty of friends with AR variants, two of which who have short stroke versions. They all spent in excess of 1k for the gun, accessories and such and my father's $500 Mini-14 shoots just as well if not better (it is a 2008 with forged barrel).

So.... you have no first hand experience with DI weapons under operational conditions to base your "hatred" on.
OK then.

I'm not a math person by any means, all I do is design concepts and such.

You arent going to get past the napkin stage then. If your ideas arent based on tacit knowledge, actual hands on skill or anything even remotely empirical, you don't have anything at all.

In fact, at my college we adopted a computer security system I aided in designing.

Neat.

 

[Dreamcast270mhz]

So, just reviewed my sources for John Pedersen's rifle design and it was only 8 lbs, in a similar caliber to what I was thinking (6.8 Rem or 6.5 Swede). All things considered, this concept I feel has potential to get off the ground, pending some more research, more detailed design and such. Pedersen's design used waxed cartridges to ease extraction, replaced here by the fluted chamber.

Things pertaining to actual design, building/testing will have to wait a few years until I can start my mechanical engineering degree. In the meantime, finalizing a system that has potential, and is patented will suffice.

I like how people don't take into account that many designers started out like me, zollen and other people with great ambitions. I don't see instant success and I don't see this as the only design I will come up with before I enter a 4-yr college in 2 years, but it is promising and based on past designs that came close to manufacture.

@45auto

Look up John Pedersen, his toggles used were up breaking ones like mine too.

 

[Jon_Snow]

I like how people don't take into account that many designers started out like me, zollen and other people with great ambitions. I don't see instant success and I don't see this as the only design I will come up with before I enter a 4-yr college in 2 years, but it is promising and based on past designs that came close to manufacture.

Yes, but they all followed one of the basic tenants of design: you don't design something JUST to be different. What advantage does this system have? No one adopts a new design unless there is a definitive reason to do so, and there doesn't seem to be any reason here.

 

[Dreamcast270mhz]

It is generally simpler than gas operation, with fewer parts/ less barrel machining, can be free floated as there is no gas tube hanging off the barrel. It also has potential to be easier to port the design to cartridges with different pressures, mass of the bolt is directly proportional to the total force exterted by the cartridge. These systems are also simpler to clean.

 

[Sam Cade]

It is simpler than gas operation, with fewer parts/ less barrel machining, more accurate as there is no gas tube hanging off the barrel.

It also is easier to port the design to cartridges with different pressures, mass of the bolt is directly proportional to the total force exterted by the cartridge. These systems are also easier to clean.

"It depends on what the meaning of the words 'is' is." –Bill Clinton

Since there is no weapon you can't say things like "more accurate" or make claims as to the nature of its operation.

Its an Incomplete Comparison.

 

[Dreamcast270mhz]

I fixed it, thanks for catching that...

 

[45_auto]

It is generally simpler than gas operation, with fewer parts/ less barrel machining, can be free floated as there is no gas tube hanging off the barrel. It also has potential to be easier to port the design to cartridges with different pressures, mass of the bolt is directly proportional to the total force exterted by the cartridge. These systems are also simpler to clean.

I'm still trying to figure out why you're posting here. You obviously know more about everything than anyone else!

The first two years of engineering school are basic mathematics, physics, calculus, materials, statics, and dynamics. Come back to this thread 4 years from now if you make it through those first two years of engineering basics and you'll get a good laugh out of it!

Good luck!

 

[Dreamcast270mhz]

Uhh, no. I don't make claims, but I am very mechanically oriented. When I was at the range about 3 months ago, a guy downrange had his Auto-5 and was trying to figure out why it jammed. In 2 minutes I had the thing apart, and put it back together in about 3 minutes.

I had no prior experience with a long recoil action, the owner was a retired Navy vet who collected all sorts of guns. I am one of those guys who you can hand me something, I take it apart and put it back together and by that time I have 90% of the operation down, not seeing it fired or any diagrams.

 

[tyeo098]

How is it simpler? In your original description I got tired from counting the moving parts.
And I tried to explain what was wrong with it the best I could, and why.

The best gun would only have 1 moving part, bolt(/carrier group), hence the stoner system we know and love today. (or the Kalashnikov system, as the only moving part there as well is the BCG too)

The best thing to do is to find a way to unlock the breach without moving anything.

Also,

In 2 minutes I had the thing apart, and put it back together in about 3 minutes.

Impossible, Browning himself wasnt able to do that! (Auto5 internals are SCARY!)

 

[45_auto]

I don't make claims, but I am very mechanically oriented.

Where do you go to school?

If you think you're mechanically inclined, put your money where your mouth is. Join a FIRST robotics team and build a robot to compete with 2500 other high school teams from around the world. Show us what you can do. Should be a simple competition for someone with your claimed abilities that's capable of designing a gun. My guess is you've never built anything from concept to completion.

I've been a FIRST mentor helping high school kids build robots for 6 years now. We've qualified for the World Championships 4 times, best finish was 12th. There are many aspects of mechanical design that you are not aware of just because you haven't been exposed to them. Being mechanically inclined doesn't necessarily mean you're able to design a mechanical system if you're incapable of learning and understanding the basic building blocks. Nothing wrong with being a great technician or gunsmith, but it's not the same thing as design engineering. Being able to take existing systems apart and put them back together again is a good way to learn what's out there.

The 3 minute video below shows this year's Mandeville High School robot, designed and built by a team of 10 high school kids. It finished 5th at the regional competition, didn't qualify for the World Championships since only the top 3 get to go. If you're really interested in learning mechanical system design skills in high school, there's no better way to do it. It's very difficult to find kids in America these days who do more than talk and fool around on the internet. Unfortunately, talk is cheap (especially when you don't know what you're talking about) and doesn't get the job done.

http://www.youtube.com/watch?v=yPf-RsseeEE

My youngest son just graduated last week with his mechanical engineering degree, he's going to Georgia Tech in the fall on a full scholarship to get his PhD. Out of the 50 engineering Master's degree graduates, 9 were from this country. All the rest of the were all from China or India. There were 11 PhD engineering graduates, 2 were from here, all the rest were from China or India. Not hard to understand why the US is losing technical jobs and leadership so quickly.

You seem to have a very limited viewpoint on what it takes to design something that works. Hopefully you'll prove me wrong and actually design and build something, but my impression so far of you is that of an "Internet Commando"!

 

[PercyShelley]

I've actually never understood why all the new GPMGs and SAWs are gas operated instead of short-recoil. There's no gas system to fill with carbon, and while the carbon fouling issue is probably overblown in infantry rifles machine guns have much more rigorous firing schedules. Supposedly brens had issues with the gas block getting clogged after a few thousand rounds and some barrel changes. Additionally, the barrel has to move relative to the receiver anyway, so one need not worry about it threading to the receiver when designing the quick-change barrel.

Then again, I can't think of any 5.56 recoil operated designs. That cartridge would impose a fairly high ratio of barrel mass to recoil momentum, so maybe it wouldn't work that well. 7.62 NATO recoil operation seems to work just fine though, I can't fathom why there aren't more MG3 clones and derivatives.