16ga.com ~ View topic - pressure between smokeless and black powder

I know this has been discussed before, but I haven't been able to find the thread; so please bear with me.

I have a Tolley English single barrel in 16 ga coming my way, it has Damascus barrels.

I purchased it from Vintage Doubles, whom I have a high respect, the owner said he would shoot it with 2 1/2" Rst shotshell smokeless powder, rather than the Game Bore Black powder as the pressure generated by the Game Bore's were higher than the RST smokeless loads.

Approx 6200 psi for the Game Bore's, I am awaiting info on the pressure of different RST loads.

NOW, this leads to the question: Black powder is an explosion, smokeless is a burn, right?

So which pressure is harder on the gun, smokeless or Black, or does it not make a big rat's ass?

I have a case of RST's 1oz loads at 1200 fps, which RST has informed me have a pressure of 6800 psi., but am afraid they may be too hot for the old girl.

Any info would be appreciated.

Dale

Joined: 06 Aug 2009 Posts: 960

The burning events, time to peak and otherwise are very similar, between Black Powder and Smokeless Powder.

I believe Woodcock posted a nice chart showing the similarity.

Maybe he will post it again.

Someone else will have to give you the OK to shoot smokeless in a damascus barrel, as I don't own any, and I don't know much about damascus barrels.

Revdocdrew has a TON of information about damascus barrels.

Maybe Revdocdrew and Woodcock will wade in and give you some good advice.

Mark, thanks.

Dale

Member Joined: 02 Oct 2007 Posts: 1975

I have a Damascus barrelled LC Smith and I shoot loads up to 7000psi with no problem. The reason for staying down in pressure is because of the wrist area of the stock. That is the weak part of the gun. I reload my own though.

[quote="spr310"]I have a Damascus barrelled LC Smith and I shoot loads up to 7000psi with no problem. The reason for staying down in pressure is because of the wrist area of the stock. That is the weak part of the gun. I reload my own though.

Thank you for your input, I was led to believe from various sources, that the problem with Damascus wasn't the way they were made, OTHER THAN, rust could develop between the various strips used to make the barrel; thus resulting in rust developing between the bands.

No mention was made as to the wrist of the shotgun, I can easily keep the pressure under 7,000 psi, but I am not sure that would be good enough?

Dale

Joined: 28 Jan 2009 Posts: 107

I don't believe chamber preasure has ANY effect on the stock of the gun........with that being said , the weight of the load along with the specific velocity, would....that would be your calucated recoil, if you are a member of the low preasure group the excel spread sheet willl calculate that for you. Might be a good idea to have a gunsmith who deals with this type of gun look it over.

The RST loads I have used were the 7/8's light, I can't rember exactly but they were very low preasure.

Jack

My 16 is a Joseph Lang, rebarreled by James Woodward in damascus. The gun dates from 1866 and the barrels probably date to 1872 or earlier. I shoot RST 2 1/2" loads and low pressure nitro reloads in this gun. In the 2 3/4 years I've owned this gun I've shot more than 500 RST's and 2,500 nitro reloads through it.

My J&W Tolley is a 12 bore that dates to between 1887 and 1894 and has damascus barrels. I've only owned this gun six months and have shot about one flat of RST 3/4, 7/8 and 1 ounce loads plus about another flat of my 7/8, 1 and 1 1/8 ounce nitro reloads through it.

Kirby Hoyt at Vintage Doubles has a good reputation but I would still have another knowlegeable gunsmith measure the barrel wall thickness and look at the barrel. If he says OK then I would shoot RST's or equivalent nitro reloads.

From what I've read I believe that because of the similarity of the pressure curves it's the maximum pressure generated that matters not whether the powder is black or nitro.

I reload straight from the Alliant, Hodgdon and other reliable guides for all of my modern guns (including my 20 gauge 1926 Fox Sterlingworth ) but in my pre-1900 damascus guns I only shoot loads that I have sent to Tom Armbrust for testing.

Pressure has no effect on the stock - it is recoil that damages wood and that is determined by the velocity and weight of ejecta, not the pressure.

Flychamps, as you know I am dealing with Kirby Hoyt of vintage Doubles, his gunsmith is Scott King, who I have knowledge of, he has done some choke work for me.

This little single shot only weighs 4 1/2 pounds, that makes me try to be extra careful.

Thanks,

Dale

FlyChamps, the barrel is suspossed to be "bright with only the slightest amount of pitting".

The minimum barrel thickness is .032.

Dale

Joined: 26 Apr 2010 Posts: 3177 Location: NCWa

Chancing the possibility of recurring the wrath of some, I'll answer your question: Black powder is an explosive, but when ignited in a closed space where the pressure builds on a shot charge seated firmly on it, the generation of pressure per unit of time is predictable & can be graphed. Nitro based smokeless powders burn as a function of the pressure involved and it has a much higher energy than black powder. So a smokeless powder load can imitate the pressure curve of black powder and as long as that is done, there is no great difference on the operation of the gun. the danger is that since the burn rate of smokeless powder is a function of the pressure, small changes in charges result in an increase in pressure, which increases burn, which increases pressure- an so on; so it is very easy to run pressures way up. But if you stick with pressure tested loads and keep the pressures within the levels of the guns design, you should get a lot of pleasure and use from the old gun. Smile

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan

Dave, thank you for the info, RST doesn't make 2" 16 gauge shells, but does make 2 1/2" 3/4 oz lite loads.

I will check out that web site. Smile

Dale

Member Joined: 27 Jun 2005 Posts: 1545 Location: Michigan