How do calculated the pressure rating of a bolt?
Specifically, I am tapping some stainless steel pipe to make a rifle barrel. Project is a homemade matchlock just to say I did, and fire once a year to feel proud of myself. I want to plug one end with a bolt (5/8), and was wondering what length of bolt would be required to achieve a 15,000-20,000 psi rating.
What caliber and what is the wall thickness? 1/2 to 5/8 should be plenty for black powder. cant speak or testify other than I assembled a BP rifle that I screwed in the breach plug loaded 150 grains of BP, 2 RLB, set a 30 second cannon fuse and ran for hell. Everything held together and have taken 3 deer and shot over 150 times with 50 grain load.
Nose through this collection for a couple of days http://s1131.photobucket.com/user/runastav/library/?sort=3&page=1
> I am tapping some stainless steel pipe to make a rifle barrel.
Are you terminally stupid, or simply suicidal?
How utterly fucking STUPID do you have to be to use a bit of "stainless pipe"?
>>945222
see pic. It'll be .50 calibre round ball. I was just figuring somewhere between a 2" or 3" 5/8 bolt because overkill never hurt anyone.
>>945229
Will do
>>945247
Are you confusing piping and tubing?
s=Pr/t
>>945308
>s=Pr/t
I am not learned, what variables are those?
>>945143
Right now there's a barrel maker somewhere, maybe from Krieger, maybe from Colerain, reading this thread and facepalming himself like a son of a bitch going, "Of course! Stainless PIPE! And all this time we've been using solid bar stock and machining it to close tolerances!"
But seriously, I've heard stories about guys doing this and being fine, but it's a crap shoot OP. Think about getting a cheap, used shotgun barrel instead, and only loading it with wadding over black powder? You'll still need to weld the breech, so you can still get your kicks, but it might be a little safer.
>>945143
Interesting note. Antique guns used slow burning gunpowder and the pressure behind the bullet built up all along the barrel as it was exiting. New guns of the same type, use fast burning gunpowder that produces higher pressures closer to the back of the barrel. When you use fast gunpowder in an antique gun it will normally make the barrel explode because all the pressure is in one place instead of being more distributed across the entire barrel.
>>945143
Stainless is a relatively soft metal. You may want to consider something like inconel. The higher nickel content makes it quite a bit stronger.
>>945670
...You've got the backwards. The majority of the pressure if BP weapons was in the chamber.
>>945689
This anon is correct. Black powder is an explosive, modern (smokeless) powders are propellants.
>>945670
>Interesting note. Antique guns used slow burning gunpowder and the pressure behind the bullet built up all along the barrel as it was exiting.
That was the justification for the longer barrel. The pressure was still intense in the chamber area. I think.
>>945672
Schedule 80 still has a burst pressure of 20,000, which is about double proof.
>>945698
So should I be using smokeless or BP?
>>945672
seamless inconell pipe costs at least 50 bucks/inch
>>945143
Just so you know, the psi rating of a firearm doesn't correlate with the burst rating of a pipe. Because a gun is vented on one end and pipes are rated for closed systems. Meaning you can probably get away with any black pipe or pressure-rated seamless steel pipe anywhere. A low-pressure blackpowder number isn't going to shatter any pipes or bolts. Basically anything sturdy and made for pressure or structural loads will work.
>>945777
>So should I be using smokeless or BP?
Stick to BP. Generates much lower pressures per volume than smokeless. Either straight-up BP or BP substitutes will work. Don't dabble with smokeless unless you're really sure of your pressure calculations.
OP a rifled blackpowder barrel is like $150 - 200 from Green Mountain or Track of the Wolf. Unchambered barrel blanks are like $30 - 80 from Numrich. Please don't risk your life fucking around with pipe.
>>945689
>>945698
>>945777
You misunderstand what what said. If you use smokeless in the old stuff it blows up the barrel because all old antiques used black powder which is not as powerful as smokeless. Even modern "black powder only" muzzleloaders can't use smokeless for the same reason.
If you don't use the correct powder, you'll end up with a pipe bomb, missing body parts, and/or dead.
>>945143
Use black powder, smokeless ONLY if you are extremely sure it can take the pressure.
BP is much safer. To add to that, look up before and after pictures of people who have loaded older black powder revolvers with smokeless.
Not pretty.
force acting on a bolt when used as a plug = force(psi) / threaded area(circumference of bolt x length of threads threaded into barrel)
the strength of the bolt is determined by the grade of the bolt grade 5, grade 8
in your case x=20000psi / .981"sq(1/2" of bolt threaded into end)
x= 20387psi
you will need a bolt that can withstand 20387 psi of force. a grade 2 bolt with 1/2" threaded into the end will work
>>946202
I see your math, but am not sure where you got the .981
All I know is that I tapped the pipe, and I can thread a 5/8 stainless steel hex bolt 2 inches into the pipe.
Sound sufficient?
>>945310
stress = Pressure * radius / wall thickness, its the formula for the tangential tensile stress in a thin-walled cylindrical pressure vessel. A rifle barrel is certainly cylindrical but hardly "thin-walled."
For a thick-walled pressure vessel you can use this:
http://www.engineeringtoolbox.com/stress-thick-walled-tube-d_949.html
If the stress exceeds the ultimate tensile strength of the material, the material will rupture. If the stress exceeds the yield stress of the material, the material will yield (stretch/bend) but not necessarily rupture. Either is bad, but at least the latter won't rip half your face off.
On top of this, a safety factor is ALWAYS a good idea. And don't even fucking think about firing this thing from the shoulder before you've proofed it by putting it in a clamp and pulling the trigger from afar with a string.
>>946129
This is correct, but black powder still is an explosive and makes its power at the breech. It does not continue burning as the projectile moves down the bore. A round ball in a muzzleloader using black powder starts slowing down at somewhere around 16 or 20 inches? But you are 100% correct, it does not have as much pressure per grain as modern smokeless. I know, I'm being not picky. Sorry.
>>945777
The smallest muzzleloader barrel you'll find in 50 cal is 1" at the breech, yours is .840? And your actual ID is .540? Sounds smallish, OP. Length of threaded portion isn't as critical as you'd think either; antiques usually have a 1/2" threaded section, modern ones use 5/8ths "just to be safe," and it's usually 12l14 leaded steel. You'd better be double damn sure your pipe isn't welded seam, too. If this thing fails it's not going to strip the threads and imbed the bolt in your skull, it's going to burst at the breech, send chunks of wood into your forearm, blind you possibly, surely deafen you, THEN it's going to blow the bolt back and imbed it in your skull.
I hate to say it, but my gut tells me that in spite of all this, this thing will probably work; but there is no way in hell I'd be within 50' of you if you were shooting it. For the love of God, use a machine rest, start with like 10 grains of black powder, don't go higher than 30 (make that 25...), be well away from it when it discharges, and never trust it. And I'm really glad I'm anonymous right now.
Read and enjoy
http://americanlongrifles.org/forum/index.php?PHPSESSID=7lv4lmgqv9b3feos4fisfp5s14&topic=38810.0
>>946053
https://www.youtube.com/watch?v=BVN8_WeleAA
Buy a proper musket barrel unless you want to grenade your face.
Then fit your lock and enjoy.
Some ideas are not wise to DIY. You can buy a blank barrel and thread that for a breech plug. Same effort, but proper material than random pipe or tubing so same "accomplishment".
>>946326
>I hate to say it, but my gut tells me that in spite of all this, this thing will probably work; but there is no way in hell I'd be within 50' of you if you were shooting it. For the love of God, use a machine rest, start with like 10 grains of black powder, don't go higher than 30 (make that 25...), be well away from it when it discharges, and never trust it. And I'm really glad I'm anonymous right now.
OP, listen to this man. Godspeed.
>>946748
no fuck that, Colt Walker revolvers took 60 grains erry day. Modern BP rifles have to be not just strong, but lawyer strong, ya know. Just do remember to proof any gun with at least a double load. But do, for the love of god PLEASE DO remember to firmly pack your powder and ball. Loose powder, or a chamber with an air gap, will cause extreme pressure spikes. The flame propagation will become faster than the burn rate of the BP, causing it all to explode at once, not in an even cylinder.
>>946833
Oh also, if you stick with that pipe, look into getting some .54 cal balls, not .50 cal. Old guns measured caliber on the lands, not the groves. Also, since you don't seem to know much about black powder OP, you probably don't know how powder is measured. A BP "grain" is not a traditional grain, but a measurement of "volumetric weight" and therefore can't be measured with a scale. HOWEVER, it also means black powder is not an exact science because it was developed by people who thought volume=weight.
>>946836
This guy is right, and don't use a modern powder measure, they have been known to explode from guys trying to use black powder in them.
According to OP he just wants it to go bang once a year, he's not taking down a bear, or holding the thin red line or anything. Let him use a .495 ball over 15 grains of black powder, less pressure in his pipe bomb, and that way he might be able to type out a report for us with the two fingers he has left.
Joking aside, I really would like to hear if this thing works or not.
>>945143
Idiots like you ruin it for responsible gun owners OP.
Buy a barrel, then make a gun. You're obviously in over your head, don't blow it off.
>>946846
You are an even bigger fag than OP. The only thing more American than buying a gun is making your own and telling da guberment to FUCK OFF.
>>946833
I was aware of the grain measurement. But the eyeball formula I was told was that your grain load should be the sameish as the calibre. So, since I will be shooting .50 calibre round ball out of this contraption, I would use 50 grain of BP.
Of course, I would build up to that, as as some other guy said, try 100 grain as a doubleproof.
All from a vice because it is more functional and cheaper than a gun rest, if you haven't picked up on the theme of the project yet.
>>946846
>>946848
1) I am Canadian
2) I am building a matchlock rifle, which is considered an antique, and therefore not a gun, as per Canadian law (unless used in the comission of a crime.) So therefore, I am telling the RCMP "You can't touch this" while they lock at me with wide eyes and think I am a whacko, not a responsible gun owner.
>>946844
I have this week off, I might be able to at least test the barrel this week, since all I really have to do to make it complete is drill the match hole and attach a bowl.
>>946893
>>I am Canadian
And with that, the entire thread began to completely back OP in his endeavour. Yes, definitely proof it before you do any more work, and how are you planning on attaching this thing to the stock, assuming this based ass Canadian pipe bomb holds together? I'm the anon who said my gut tells me it might work, but with walls that thin I wouldn't attempt dovetails in it like a flintlock. You talking wrapping a strap around the barrel, or would you try soldering a lug on the bottom, or what?
>>946893
Wait... A vice? You are talking about going outdoors, correct? WAY outdoors, where no one can get hurt, and you have some foolproof method to set it off where you can be like, 50 yards away, behind a huge tree when it goes boom? It would probably be smart to AT LEAST use some good calipers to measure your breech before and after firing, a micrometer would be better. If you can't think of a way to test it safely, don't do it anon.
>>946893
how is it an antique if you just built it eh?
btw if it shoots its a firearm theres no such thing as an "antique firearm" in canadian regulations so have fun with your illegal homemade firearm
>>947548
http://www.rcmp-grc.gc.ca/cfp-pcaf/fs-fd/powder-poudre-eng.htm
>Muzzleloaders made after 1898
>All matchlock, flintlock and wheel lock long guns are considered antiques no matter when they were made. Like older firearms of these types, they are exempt from the licence and registration requirements set out in the Firearms Act.
I might have mixed up the "not a firearm" part with flare guns, but as you can see, there is such a thing an antique firearm. And, in Canada, you are allowed to build any firearm you have the appropriate license for, but you are not allowed to transfer it without additional licences, and are suppose to register its design with the RCMP.
But, again, as above, this firearm does not require a license, and therefore, anybody can build it legally. The only hitch is you have to be 18 to buy black powder.
