38 S&W pressures?

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mike p

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so the old 5 shot top break 38S&W pat date 1886? im sure was / is BPowder only so how do you find what the pressures of a case full of BP would be
to compare to some low pressure smokless
as we dont allways want to shoot the holy black
but love shooting these old top breaks . i got 2 of them & my boy has one
 
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There is a strong conviction out there that a black powder cartridge revolver can never fire smokeless loads, no matter how low powered. That is false, and I almost always shoot smokeless with my own antique revolvers. Bullseye powder works, but an even better one for this is Trail Boss, because light weight charges of this powder will still have enough volume that a double charge is much more readily apparent. And a double charge is your real danger here.

Every one has their own method of developing light weight charges, and I have given mine before in this forum.

Donning the asbestos undies...
 
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I'm no expert on antique firearms, but I know this...3.5 gr of Trail Boss in my 38 airweight j frame is a popcorn load... Its like a cap gun But wow, is it accurate.
 
His statement "you get a different pressure curve" is false. The pressure curve is almost identical with similar loads.

His statement "you get a lot more pressure with smokeless" is false. A black powder charge giving, say 10,000 psi has the same pressure as a smokeless charge giving 10,000 psi. 10,000 psi =10,000 psi, and the "pressure curve" (time vs pressure) will be nearly identical.

That was no discussion; it was a monologue, with him passing on false information that he has heard.
 
I am a very big believer in Black Powder. That being said I also like Trail Boss. When Trail Boss first came out, there were instructions on making your loads, my method is based on those original instructions, and I have had some very good results. Start with the bullets and cases you are going to use. Measure from the place your crimp is going to be on the bullet, to the base of the bullet; this is the critical measurement! If you change bullet, start all over! Now add 1/16" to this length, put Trail Boss in case to this height. Now weigh that charge, and that is the charge for that bullet. You can make the gap 1/16" bigger (1/8" total) but that is the limit. These will most likely be your mast accurate loads, if it won't meet your requirements, you best bet is try a different bullet style and start over. At these low velocities you want to get soft lead bullets 1/1000" over bore diameter. NEVER COMPRESS TRAIL BOSS!!!

This method works with rifle and pistol cartridges. I developed a 38-55 rifle load for my 1885 Winchester that shot 4, 5 shot, one hole groups in a row by 4 different shooters using the globe and tang sights at 100 yards. I used that 1/16" method gap on several other cartridges. No the others didn't shoot this well, but I am very happy with those results as well. Ivan
 
mike p said:
...so how do you find what the pressures of a case full of BP would be
to compare to some low pressure smokless...
Click to expand...

It should be the same as the SAAMI max. pressure using smokeless powder. You know, the ones you shouldn't be using. If I get a chance to look I'll try to find out for sure.
 
A few things...

Warren Sear said:
His statement "you get a different pressure curve" is false. The pressure curve is almost identical with similar loads.

His statement "you get a lot more pressure with smokeless" is false. A black powder charge giving, say 10,000 psi has the same pressure as a smokeless charge giving 10,000 psi. 10,000 psi =10,000 psi, and the "pressure curve" (time vs pressure) will be nearly identical.

That was no discussion; it was a monologue, with him passing on false information that he has heard.
Click to expand...

The pressure curve between Bullseye and H110 is different. There may be a smokeless similar to gunpowder but I don't know what it is. I'm sure that why they use powders like Triple 7, Pyrodex, etc.

You are right, 10,000 psi = 10,000 psi. I took his comment to mean that you won't surely blow up a gun, but without test equipment, knowing what quantity of what smokeless powder that equals a BP load is really chancy.

I think that if you start very low and make sure not to stick a bullet in the barrel you could work up a load that would work, but I'd have to know more about what I was doing to try it in an old BP gun.
 
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I checked all my older books but couldn't find anything on the pressures of black powder cartridges. I did find data from 1926 that listed smokeless powder and black powder loads side by side and they only listed one pressure limit for both, which is what I expected to find.

But the problem isn't with maximum chamber pressures, as too many people seem to think, it's with what some would call the "pressure curve".

After the responses to the video above, I had to watch it, even though I swore I'd never waste my time watching another one of Hitchcok45's videos. He obviously doesn't understand what he is talking about, but the fact still remains that the reason you should not use smokeless powder in a black powder firearm isn't because of "pressure" it is due to the way that pressure is generated owing to the burning rates and characteristics of the two types.

His biggest mistake is in his demonstration comparing the burning rates between the BP and the Unique. Black powder is an explosive and smokeless powders are propellants, they are very different. Black powder burns very fast and violently in the open air while smokeless is quite a bit slower and less impressive. But smokeless powder isn't meant to be used in that manner and when confined it burns a lot faster and more violently than black powder because it need the heat and pressure of confinement to reach it's full potential.
 
Well, let's put it this way....

I listen to hitch when he tests and compares guns but he's not a chemist or physicist and taking it all with a grain of salt, what he said boils down to the fact that smokeless CAN be used in BP weapons, but you'd better know what you are doing because it can easily be unsafe without proven data.
 
The SAAMI pressure limits are 13,000 CUP for the 38 S&W. The reason why the pressures are so low is consideration for the older and weaker revolvers that have been around since before the 1900's.

Lyman #47 has data but only lists pressures for W231. I'm sure the other loads are similar.
1.9gr W231 = 6,400 CUP, 2.8gr W231 = 12,300 CUP under a Lyman #358480 bullet. (133gr without lube)

Byllseye - 2.0gr to 2.9gr
Red Dot - 2.4gr to 3.1gr
Green Dot - 2.5gr to 3.2gr
Unique - 3.5gr to 4.1gr
SR7625 - 2.7gr to 3.3gr

Always verify the data for yourself.

IF you are still worried you can always load one of the BP substitutes but don't use Triple7. Pyrodex P will do a good job for you.
 
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Thanks for the link Warren. If you want to see the "proof to the contrary" that glowe mentioned, come on over and I'll show you plenty of it. I would invite glowe over too, but since he contradicted his proof with his own opinions later down, I doubt it would do him any good.

My research of the subject began when I was looking at a copy of the Cartridges of the World" and noticed that factory loads of BP cartridges gave higher velocities than factory loads of smokeless. I wanted to find out more, and did, and none of it was on the internet. I am going to try to find a copy of that article glowe referred to though as those traces contradict everything I'd read, and why the factory loads would be different.

Anyway, the reason not to use smokeless powder in a black powder gun is not the maximum chamber pressure. It is damage due to stretching and erosion because of the soft steels that were used at the time. Shooting them with smokeless will not make them "grenade" as was suggested in the link, at least not for a while, although it could happen eventually.

I have two top break revolvers that I shoot with smokeless powders. They were made for smokeless but due to the inherent weakness of the top break action, I use minimally low charges of Bullseye. I also have an early S&W .32HE. I do not shoot it at all.
 
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How would today's factory loaded .32 or .38sw be in older BP designed guns like the 1st and second gen Iver Johnson's or mod 1 & 1/2 Smith and Wessons? I have shot Rem and Win loaded lead RNL from both rounds in older guns, very low velocity stuff.
 
Jellybean said:
Anyway, the reason not to use smokeless powder in a black powder gun is not the maximum chamber pressure. It is damage due to stretching and erosion because of the soft steels that were used at the time. Shooting them with smokeless will not make them "grenade" as was suggested in the link, at least not for a while, although it could happen eventually.
Click to expand...

Otreb, I'm not sure what the generations of Iver Johnsons revolvers are, but I'm sure the first generation, as well as the S&W 1 1/2 would fall under this. The second generation would depend on when they went to the "new" process.

In anticipation of counter arguments, I started looking through some of my
"reloading manuals" for their opinions on the subject. So far the only one I found that said anything about it was Accurates Loading Guide number one, which said the same thing I did above. I have also been looking for information about Sherman Bell's article, without much success.
 
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