In relation to Clammy's recent post - https://voat.co/v/TheGunClub/3149176
I wondered if one could make an open bolt RIFLE instead of a sub gun. In theory, all one would need was a heavier bolt. The weight should be proportional to chamber pressure, right? If not exactly proportional, at least in relation to it somehow.
So I did a little research and I found, of course, someone else already had the idea. I mean guns have been around a long time and I'm not even 25.
Here's a page that describes open bolt weight in relation to different cartridges of diff speed and weight.
http://orions-hammer.com/blowback/
But it occurred to me, .300blk subsonic is basically a .45acp by weight and speed. It has double feed mags and is easily suppressed. So wouldn't bolt weight be about the same as a .45acp? That's 2.3 lbs of steel.
One CUP of steel is ~4.1lbs. So with a bolt that weight one could made a blowback .300blk if only subsonic was used. 10mm would need 2.8 lbs.
But can you do 5.56? Yes of course you can. You can do anything. But what's the weight? About 7 lbs for a .223 remington.
There's more.
What about 'advance ignition'? That's pretty complicated and can't really be done by most peons in their garage, myself included. But if done, it would allow one to use the forward momentum of the bolt as a surrogate for bolt weight.
That means a lower weight for more powerful cartridges. I think if you wanted to do this, you would need to use some integral calculus. Any ideas about this? I guess we would need to start from bullet velocity and back pressure. From there we can add backward velocity. However, I'm not great at calc and don't care to do it.
@Clamhurt_legbeard @Nadeshda
ExpertShitposter ago
I was looking at that particular orion's hammer page last year when i made a little something something in my garage. I calculated bolt dimensions for 9mm and instantly it was clear that making anything bigger than 9mm in straight blowback was pointless.
You have to consider the reason why would you even make you own gun, since its almost always be shitter than anything you can buy. The only reason is an untraceable firearm, to be used by drawing from concealment, in a time when all firearms are banned. Or if you wanted someone removed, and the gun melted down with no remorse for the cost, because it was free for you. In both cases, the gun would have to be light, no heaver than say....6lbs. If your bolt alone for .223 weighs close to that......yeah......
Luckily, recent studies have shown, that caliber wars are a meme, as there is no noticeable difference in killing power between different handgun calibers after you get into 9mm, and almost everyone dies from 3 shots of 9mm, vs 2 shots of .223. And if you make an accurate weapon, a head shot with a 9mm is guaranteed death. Considering the people who you would be fighting in such a scenario would be wearing body armor anyway....you would need to go for those head shots anyway. So killing power becomes not so critical.
One advantage you would still get from .223 is a flat shooting trajectory. If you wanted to keep within the pressure of 9mm to maintain a bolt weight of 1.7 - 1.5lbs, but flatten out the trajectory, you could make a custom Tokarev style cartage. A case turned on a lathe from a single peace of 8mm brass rod, elongated to maintain the same volume as a 9mm case, fitted with the same primer, and crimped to a 5.56mm bullet turned from a 6mm solid copper rod. Not sure what kind of velocity would you get, but it would certainly be flatter than a standard 9mm.
That's my theory at least. Its something i will test in the future when i get the time.
As for advanced ignition, i wouldn't bother with it. Even if you could make it, design should be made super simple, so that most people can do it. Otherwise you didn't make anything revolutionary, just....cool toy for your self. I would rather make a bolt action .223 at that point.
clamhurt_legbeard ago
bolt actions and break actions are much easier to make for rifles than semi auto
best designs are probably blowback pistols
revolvers
blowback open bolt smg
bolt action rifles
ExpertShitposter ago
Easiest design is "thread action single shot pistol". Don't ask me how i know ;D
middle-path ago
Just like the RN-50 but I think they're fucking retarded.
ExpertShitposter ago
I think they are brilliant. It depend's on what your goal is. If it is to make an untraceable gun for your self...yeah, its retarded, because you can do better than that. My goal is different tho.
middle-path ago
Hmm, yeah I can agree with that.
A gun to remove a single threat in a self-defense scenario, in minecraft. Or to get to another gun? Seems pretty good.
ExpertShitposter ago
Yeah. Imagine say, you were playing minecraft, and most characters are wearing say.....yellow vests. But the zombies and skeletons are wearing blue vests! In all the commotion, there would be plenty of time to reload say...a break action single shot. Now imagine if every tenth allied player with the yellow vest had such a pistol....
middle-path ago
Yes, or better yet, I'm playing minecraft(yay! :3) on the 'City Name Here' server and I come in contact with a Netherman who has been terrorizing the server for years. He's levied unfair taxes and taken goods/children from the players on the server. He's essentially the equivalent of a king or senator on the server.
I'm cornered in an alleyway and the Netherman puts me in a self-defense scenario. What if, as a last resort, I am forced to defend myself with an improvised weapon with a homebuilt silencer.
I wouldn't be happy about taking the Netherman's life, but I would be happy that I had defended my own.
ExpertShitposter ago
Netherman's have a tendency to force our hand. Nobody is ever happy about the devastation. I also hear night sights are very clear against "dark" background tones.
clamhurt_legbeard ago
lately im looking at zombies and how they always have exposed necks and joints
lately im looking at squirrels and how small they are
lately im looking at how effective at 200 m a 22 can be
22 is very simple
very very simple
that receiver is cast zinc magnesium
so tiny and quiet
ExpertShitposter ago
I've learned, than even aluminum is enough for a 9mm barrel. Not kidding.
clamhurt_legbeard ago
did you rifle stuff too
ExpertShitposter ago
No, i saw the results from a video. I'm gonna order a rifling kit, its pretty cheap actually.
clamhurt_legbeard ago
can you order 22 barrel liners
those are nice too
ExpertShitposter ago
If they sell em on ebay, they would probably go through, but legally no. In EU, gunparts aren't just a lower receiver. Its anything that "bears pressure".
clamhurt_legbeard ago
barrel liners arent even a barrel
just the insert
but ya your regulations are more restrictive
hey just to make sure
youve seen my pasta right
a lot of the pdfs are from a guy named professor parabellum
he too has a family of very basic arms for defense against tyranny
like you were talking about
Page 1
Page 2
Page 3
Page 4
Powder chemistry
Borz pdf link
Table leg typewriter pdf link
Pocket sized sheet metal pdf link
World's Simplest SMG
Box tube MAC11 pdf link
STEN pdf link
Simple and compact pdf link
ExpertShitposter ago
Yeh i got a bunch of his stuff and yours.
clamhurt_legbeard ago
good man
and theres a video series on youtube where the guy builds the sheet metal one and troubleshoots it
clamhurt_legbeard ago
dude this is good shit
you want blowback in a rifle huh
well i got good news
this month has a fifth tuesday
and thats exactly what were talking about in the bonus article
but as youve already started to discover
shits tricky yo
Nadeshda ago
Cool beans!
Nadeshda ago
You know this is a good question, I am wondering whether @thebuddha and his higher level maths background would be able to answer it for you :)
Secondly, @Expertshitposter might be able to give some ideas.
I understand what you are asking but honestly I do not know where to begin.
Maybe @Awful-Falafel knows something and @Rotteuxx is very smart with his hands and mind so let me ping these people and see if they can help.