Mizar
Member
CraigC revived my interest in damascus barreled shotguns and I started to read more and more about the subject. A mighty interesting issue I must admit! The tests performed by the guy from Double Gun Journal are really an eye opener.
BP VS smokeless pressure curve and effects on guns?
- Thread starter gilgsn
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Here is something to awnser the question. The older black powder Naa mini revolvers use to also give you a charge of smokeless to use until it was found illegal because it was sold as black powder with no ffl dealer. They would shoot both. There is going to be the correct charge of smokeless to equal the black powder. But unless you have the testing equipment you will never know. Theoretical: take a 45 colt load of what ever smokeless that is safe for the replicas and pit that in the bp cylinder, if you get the bullet seated to the same length as the cases load would be, then it should act relatively close. The problem is loosing the " case capacity" when seating the projectile on top of the powder charge changing the pressure curve on smokeless powder. Then if seating on top of the powder the charge would half to be greatly reduced to no one knows where. Trailboss would be a good one to try if you were to experiment. It is loaded almost the same way black powder is loaded in cases. So again in theory. Trsilboss would act alot like smokeless as it is loaded to base of bullet for a max charge without a reference to case size, just like black powder.
Driftwood Johnson
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Perhaps you missed what I said earlier. Trailboss absolutely is not a Black Powder substitute. And it absolutely is not loaded like Black Powder, all the way up to the base of the bullet! It is loaded just like any other Smokeless powder, with X amount of grains as dictated by the loading tables. How far that fills up the case will be determined by what the loading tables say for the Maximum load for that weight of bullet. Trailboss is much too fast a powder to be considered a Black Powder substitute, and it generates a very sharp pressure spike.
The rest of your post is unclear to me, but if you are advocating loading Smokeless power into a Cap & Ball revolver cylinder, that is a big mistake. There is a reason modern Black Powder revolvers are stamped "BLACK POWDER ONLY"!
because most smokeless loads are at less than 100% load density. try this with black powder and you will get the same kaboom in your bp gun. probably why bulk smokeless powders (like trail boss) work so well in the cowboy action game.
murf
Well if you read from the manufacturer recommended way of loading trailboss it is loaded exactly like I said. That is how they recommend loading it when data is not available for your cartridge. I am not advocating it in any way. I am pretty sure I included to say you don't have the testing equipment to try it and. Used the word theoretically a couple times. I suggest you look up some more info on trailboss. Before you make comments on how it's loaded without knowing.
Also all the max loads for trailboss seem to be at the base of the bullet for the several calibers so you might have no experience with this powder from your statement. I'm going to attach a picture of how hodgdons/imr tells you to load trailboss and it clearly states this is your max load at base of bullet.
The rest of my post that you do not understand is simply saying with the proper voided air space between bullet and powder I'm sure a load for smokeless could be made to work. However again no one has this testing equipment so that is theoretical.
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DriftWood... You are 100% Correct.
Keep Trailboss away -- in any loading configuration -- from BP-designed/rated weapons
in any form other than modern/repro cartridge guns. Opinions may vary even as to suit-
ability in top-break revolvers re accelerated loosening, but I'll leave that to your experience.
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Driftwood, You are a great guy, well meaning, but I must take issue with this assessment. Any firearm passing a 30% over pressure has simply passed a 30% over pressure test. That does not mean it will not fatigue fracture sometime in the future, as continued stresses cause weak welds to break, and stress fractures to accumulate in poor quality materials. In fact, I am going to claim that continued over pressure loads will cause any steel structure to fail sooner. I had to go to the library to examine fatigue curves, but one I remember clearly showed for steels, that when steel is over stressed, its fatigue lifetime is dramatically, and I mean dramatically, reduced.
All those welds in a Damascus barrel, they are sort of like wood rot and termite damage. At some point, the structure is eat up and will fail.
Driftwood Johnson
Member
Howdy Again
I bought a bottle of Trailboss back when it first came out. It was difficult to find at that time, but I did find a bottle. I still have the bottle.
Looking back through my reloading notebook I see it was 2007 when tried Trailboss. I was looking for a mild, clean load for 44 Special. The load I tried was right in the middle of the published data for Trailboss with a 200 grain cast bullet in 44 Special. The recommended starting load was 4.3 grains, the MAX load was 6.3 grains. I chose a charge right in the middle of the data, to be sure I was not over stressing anything. I eventually chose to go with my old favorite Smokeless powder, Unique. One of the reasons I decided not to go with Trailboss for any of my Smokeless loads is a standard bottle is only 9 ounces, rather than the 1 pound you usually get when you buy powder. This probably owes to the fact of how fluffy the grains are, and a full pound would not fit into one of Hodgdon's standard bottles. Notice I was developing loads for modern revolvers, a S&W Model 624 and a Model 29.
The technique you are referring to is to determine the MAX load for any undocumented cartridge with Trailboss. A MAX load of Trailboss would most likely burst the cylinder of Cap & Ball revolver.
See the warning on the back of the bottle. Trailboss is not to be used as a Black Powder Substitute. In keeping with my policy of never shooting Smokeless powder in any of my antique cartridge revolvers, and since Trailboss is not a Black Powder Substitute, I will not use it in any of my antique revolvers.
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rdstrain49
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With all due respect, Black Powder is generally not loaded to the base of the bullet as Driftwood suggests, but rather loaded as a compressed charge. Any air gap between powder and bullet can be disastrous plus compressed BP shoots much cleaner (less fouling) than not compressed and just up to the base of the bullet loads.
J-Bar
Member
Driftwood Johnson is too much of a gentleman to drop a microphone, but he would be justified in doing so with his last post. 
Good info DJ, Well done and thank you!
Good info DJ, Well done and thank you!
rdstrain49
Member
I agree with DJ regarding the Trail Boss, nothing more to say on that. Not sure what dropping microphones has to do with anything, but I suspect Mr. DJ can likely speak for himself.
Gaucho Gringo
Member
Trail Boss was made as a powder to fill up black powder brass which has way more space than needed with smokeless powders. It was conceived as a way to prevent double charging as most smokeless powders when double charged in BP cartridge cases like 45 Colt and others don't overflow the case. Also some smokeless powders have a problem with a tiny bit of powder in a large capacity case and have erratic ignition. It has gained some popularity as reduced loads in some rifle cartridges like 30-06 and 7.62x54R for recoil sensitive shooters such as the young or inexperienced. It was never intended to be used as a black powder substitute or is it marketed as such..
whughett
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A "niche" powder so to speak, but it seems to be the nature of us humans to multi task.
RecoilRob
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One of the weird things about light charges of smokeless powder is that they can sometimes exhibit pressure spikes that far exceed their normal performance....likely due to static charge spreading the powder all around the case which is then simultaneously lit by the primer vs the normal more progressive burning when the powder is stacked against the ignition source. I had a weighed charge of 231 make a BIG flash/boom and recoil out of a 45 Colt that made people on the line look over and ask 'what the hell was that?!' No way was this a double charge...and all fired before it went 'pop' as they were designed to be light 'cowboy' type loads. But I'm certain if this had been in a blackpowder gun...the normal loads before most likely wouldn't have bothered it in any way, but that loud one sure could have ripped it apart.
If you can guarantee that the smokeless loads will perform exactly as desired every time...then you likely could use equal max pressure loads in a BP gun. Problem is I don't think you can make such a guarantee with smokeless in the pressure region where BP lives so grenading is very possible.
If you can guarantee that the smokeless loads will perform exactly as desired every time...then you likely could use equal max pressure loads in a BP gun. Problem is I don't think you can make such a guarantee with smokeless in the pressure region where BP lives so grenading is very possible.
Peak pressure in smokeless vs Pmax with BP is akin to comparing an apple to a similar-sized orange. The BP pressure application curve is significantly spread out under the peak -- akin to a push, rather than the closed-fist punch from a fast-burn smokeless propellant -- including/especially that of Trailboss
Driftwood Johnson
Member
High pressure spikes with very light loads in Smokeless cartridges are very difficult to document. Some shooters insist they cannot happen. I have never heard the static charges explanation before.
What I have heard, and tend to give credence to is a phenomenon called premature shot start. The theory is that with a very light load of Smokeless powder, as the powder begins burning it may build enough pressure to push the bullet out of the case, but enough pressure has not been generated yet to keep the bullet moving down the barrel. So the bullet stops moving, often in the forcing cone. An instant later, because the volume where the powder is burning has now become finite, the powder begins its normal progressive burn, but the stuck bullet now acts as a barrel obstruction. The pressure builds much higher than would normally happen because the bullet cannot get out of the way fast enough. In extreme cases, even with a small charge of powder, the pressure gets high enough to burst the cylinder.
When loading very light loads with Smokeless powder it is important to crimp the bullet very firmly, so it will be retained in the case until the pressure builds enough to keep it moving down the bore.
robhof
Member
To answer the 1st question, it's not the brass, but the cylinders, made of modern steel and for cartridges, the ROA is actually a modified old model Blackhawk, made of the same metal as the Blackhawk, in revolvers the bulk of the pressure is in the chamber, some dispersed by the barrel/cylinder gap, so the barrel gets a reduced pressure push for the bullet/ball.
Jim Watson
Member
The Pressure Trace literature has examples of loads that produce a pressure spike well after the normal maximum. Makes you want to stick to standard loads.
Trail Boss is a fast burning powder, burn rate close to Green Dot which is a shotshell and occasional pistol powder. Its selling point is its low bulk density which gives uniform loads in large volume black powder revolver and carbine rounds. Low power rifle ammo is possible but I for one would not use it in a black powder rifle.
Once upon a time, Speer made a one shot "cylinder" with pressure gauge port to fit a real revolver. They found that the maximum pressure occurred before the bullet had made the jump from "cylinder" to barrel.
Trail Boss is a fast burning powder, burn rate close to Green Dot which is a shotshell and occasional pistol powder. Its selling point is its low bulk density which gives uniform loads in large volume black powder revolver and carbine rounds. Low power rifle ammo is possible but I for one would not use it in a black powder rifle.
Once upon a time, Speer made a one shot "cylinder" with pressure gauge port to fit a real revolver. They found that the maximum pressure occurred before the bullet had made the jump from "cylinder" to barrel.
RecoilRob
Member
That's interesting theory of 'shot start'...never heard of that but it's certainly possible. The only place I've read where a light smokeless charge can reliably be made to cause issues is in a bottleneck cartridge where the powder MUST be kept back against the primer or bad things happen. One fellow reported that he had fired hundreds of light loads in his rifle (sorry...forget make and caliber) then without thinking allowed another shooter to fire it without telling him that the muzzle must be elevated to settle the powder then carefully leveled before the shot. This new shooter loaded it muzzle down, raised to level and fired....and it came apart.
I think it safe to say that load density is something that should be carefully considered with smokeless and might play a part in the odd cap-n-ball blowup being that the rammer can't push the ball down far enough to seat on a tiny smokeless charge and could lead to unstable/freakish combustion. After my 231 Colt incident I've used Unique exclusively as it fills the case much better and have not had another problem.
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