| huntingsgr8 |
| (.224 member) |
| 18/07/16 11:57 AM |
Black Powder Bore Gun Pressures??
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I am looking for information on the pressures generated by a 10 bore with a heavy African style charge (700 grain ball-1200 grain conical over 5-10 drams of black powder), but at this point I will take ANYTHING, and I mean ANYTHING that is remotely relevant to that. I have asked on the muzzle loading forum, shotgunworld, doublegunshop, and castboolits, without avail. Please somebody give me a hand. I am designing a 10 bore hammerless, under lever, and as I cannot afford commercially made barrels, or quality steels like 4140, and 4340, I have to improvise. Because of that I have to determine what pressure will be created by this thing, in order to determine if my barrel will survive. With what I have done so far I would consider 18000psi to be the maximum load pressure I will use in this thing. The math says I'm safe until 26000psi (and that's only the yield point of the steel), but I don't want to push it. Any and all help welcome, and appreciated!
| DarylS |
| (.700 member) |
| 19/07/16 12:40 AM |
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Re: Black Powder Bore Gun Pressures??
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The only "data" I have is for a .75 shooting patched .715 round balls weighing only 545gr.
130gr. generated 1,136fps
150gr. generated 1,213fps
There is no pressure data with the loads and the powder in the 70' when this data was produced, was poor quality.
We can extrapolate or guesstimate pressures from this data if using the same powder as equal velocities produce equal pressures in this book's data.
LUP- lead units of pressure - copper crushers do not register this low with accuracy.
1,136fps generates APPROX. 4,400LUP
1,213fps generates APPROX. 5,300LUP
Using heavier conicals, in % ratio to the 10 bore's difference between round ball and conical, we get pressures as below using G-O 2F.
1,200fps generates APPROX. 9,450LUP
Now - what a 10 drams load would produce, I have no idea.
I've shot up to 7 1/3rd drams (200gr.) in my 14 bore muzzleloading rifle, generating 1,700fps. Other than kicking rather hard, no other problems.
From the extrapolations, this load generated only 9,100LUP.
If you were to get round ball speeds up to that level, they would produce about the same pressure.
At a more realistic 1,550fps, you might develop 7,500LUP to about 8,000LUP tops, which is very low indeed.
Even (or maybe especially) armed with all this guesswork, I would not build a rifle with steel having yield strength of only 26,000psi -
THAT IS SCARY!
| huntingsgr8 |
| (.224 member) |
| 19/07/16 06:22 AM |
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Re: Black Powder Bore Gun Pressures??
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Quote:
Even (or maybe especially) armed with all this guesswork, I would not build a rifle with steel having yield strength of only 26,000psi -
THAT IS SCARY!
The steel's yield strength is 53'000 psi, if I use that as the tensile strength value in the formula it gives me the point at which the barrel will begin to yield to the pressure, in this case around 26'000 psi. Actual burst pressure estimated at 31'000 psi.
| DarylS |
| (.700 member) |
| 19/07/16 09:17 AM |
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Re: Black Powder Bore Gun Pressures??
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The bore guns do not make much pressure - however they do make recoil - giving the impression of a hot load.
As to my scary statement- it was based on your previous words.
"With what I have done so far I would consider 18000psi to be the maximum load pressure I will use in this thing. The math says I'm safe until 26000psi (and that's only the yield point of the steel), but I don't want to push it."
For interest's sake - what is this steel?
| huntingsgr8 |
| (.224 member) |
| 19/07/16 09:41 AM |
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Re: Black Powder Bore Gun Pressures??
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At worst, 1018 mild steel, at best 1026. Using a piece of DOM, it's all I have access to, and all I can afford. I understand how my initial statements could have been cause for concern, I wrote that up in a hurry. As far as recoil is concerned, well, I'm willing to see just what's what. A 3.5" Black could from my Mossberg 535 hits with about 64 ft lbs,and only bothers my neck after rapid shooting, I think it'll be fun to take it up a notch.
| Omnivorous_Bob |
| (.333 member) |
| 13/08/16 05:08 PM |
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Re: Black Powder Bore Gun Pressures??
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Contact Tom Armbrust at barbmiller49@yahoo.com.
I don't know what 10-bore data he has or what he may be willing to share, but he has by far done the most pressure testing of 8-10-12 bore rifles and shotguns of anyone I know of.
Also I remember a Double Gun Journal article from way back on 12-bores that has some data. While not translatable into 10-bore, I found it interesting how the pressure varied between brass and plastic cases and if a plastic case was crimped or uncrimped. I'll dig through my collection and see if I can find it.
Bob
| rigbymauser |
| (.400 member) |
| 15/08/16 06:13 AM |
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Re: Black Powder Bore Gun Pressures??
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A full 10dram of Swiss 1,5F will push a 900grain conical 1735 Ft/sec. Interestingly 10dram to a 982grain conical 1650-1700 ft/sec. Thatīs from a 10bore!. The power of the these 10bore stands in shade of the slightly bigger 8bore. However a heavy 10bore rifle weighs 14Ibs the 8bore add 3Ibs more. Hauling around all day I am sure 3 Ibs difference might feels a easier at the end of the day.
| DoubleD |
| (.400 member) |
| 15/08/16 11:09 AM |
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Re: Black Powder Bore Gun Pressures??
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Are you making you own barrel?
I understand costs and I would think 1018 would be fine at blackpowder pressure, it is the minimum recommended for cannon building.
The cost of a 1" x 36" 1018 is about $15 US
Same size 4140 is about $35 US.
Those are mail order prices.
Quite a bit of difference, but doesn't seem unreasonable.