Shooting Smokeless In A Green Mountain Barrel

[RedFeather]

Smokeless powders have a much different burning curve than black. Black reaches peak pressure over a long curve, while smokeless spikes early. Double-charging black is not a good thing. Double-charging smokeless is much worse. Smokeless powders are coated to burn at a progressive, controlled rate for the type of firearm cartridge they are designed for. Putting the powder into a different configuration (i.e. spread across your breech) can cause it to burn at a different, maybe faster rate. Short-starting over black powder (ball short of seated) will cause a burst barrel or walnut bulge. Short starting over smokeless may be more devastating.

In short, don't do it.

RedFeather

 

[Zonie]

I think John Taylor makes some valid points concerning the burning charactistics of smokeless powder. It requires pressure to accelerate it to a useful burning rate and the hole in the nipple may not permit enough pressure to develop to achive this rate. That could result in a ball stuck in the barrel. Then on the other hand, if enough powder is added to overcome the leakage thru the nipple the pressure may rise to a totally unacceptable amount and it's ability to accelerate the ball/bullet would be totally unpredictable.

Remember, the pressure curve for black powder (pressure vs time) is constant reguardless of the pressure it is subjected to and it is rather gradual (read, "slow") which gives a (relatively) slow push to the ball/bullet.

Smokeless on the other hand, when subjected to high pressure, generates it's full pressure almost instantly with the pressure dropping off only as the ball/bullet starts down the bore. This rapid pressure "spike" has a radical effect on how the container (the barrel) will safely resist it's effects. In fact, the rapid pressure spike reduces the margine of safety by over 50%.

One of the assumptions made in the original post is that the barrel is made of a comparable material to a modern smokeless rifle.
This assumption, in my educated opinion, is totally false.
Modern guns use alloy steels with very high tensile and ultimate strengths and are fully heat treated to assure these strengths are met.

The modern muzzleloader on the other hand is made from a low carbon steel which is very low in both tensile and ultimate strength. These low strength steels can be compared with the common cold rolled steel used for wheelbarrows and shovels.

Couple this low material strength with the weakened basic design of a muzzleloader as mentioned by pondoro, and the pressure caused hoop stress could easily exceed the ultimate strength of the material.
Putting it another way, the barrel could easily blow up or the breech plug could blow out. Probably both.

I am not saying the barrel will blow up. I am saying there is a high degree of uncertainty which nullifies any potential benifit one could hope to achieve by using smokeless powder in a muzzleloader.

 

[mikelange]

I think the bottom line ought to be that this has been tried many times since the introduction of smokeless powder, and as of yet not a single authority on black powder firearms has given even conditional approval to doing so. Most of the modern brands of muzzleloading gun barrels have been around long enough that, if any of them could safely be fired with smokeless, under any circumstances, those of us who are heavily into this pasttime would know.

I've seen pictures of black powder cartridge guns which were fired with mild smokeless powder loads. One only hopes the shooters survived; the guns certainly didn't. Since guns of this type are much, much closer in design and the nature of their ammunition to modern firearms, than even modern muzzleloaders are, the fact that it's advisable to shoot them with black powder only would indicate to me that loading a muzzleloader with smokeless is out of the question.

Something I was taught by some very wise people, a long time ago, that's in large part responsible for my still being here: when the repeated experience of many others shows that the odds are against a certain course of action turning out well, it's not a good idea to assume that taking that same course of action will turn out well for you.

 

[Jäger]

Well, nothing like waking up the board... So a few general comments after reading the responses.

Thanks for the comments regarding stupidity... those were really enlightening. As I do believe I mentioned, I wouldn't be doing this without my strain gauge setup in place, and while I hope it would be obvious, the rifle would be bagged and I wouldn't be anywheres near it when I pulled the string. I have my own range on my place, so those who assume I would be doing this at a public range can relax now.

Quite aside from reloading/casting/shooting, during my adult life I've been a miner, blast hole loader, commercial diver, and paratrooper. I have yet to spend a day in the hospital and never had an accident in those occupations.

Some of you may assume I'm stupid, I prefer to believe I put a lot of thought and planning into anything I'm considering doing that may be risky in any ways. That includes asking groups of people if they know of anyone who has done this kind of thing - by which I mean approaching it with some kind of plan and precautions, not just dumped a a full measure of powder down the barrel. And lots of interesting projects have been put aside because I thought hazards were unmanageable, by the way.

Why would I do it? Because I'm curious, because I've been experimenting with firearms for 40 years now, because it might be useful. Some people are into the whole era of black powder: the rendezvous, dressing in period clothing, nothing but authentic gear. Some are possibly into competition. Some because black powder seasons extend their hunting season. Some because they just plain like it. Some, of course, a combination of the above. Well, technical issues and questions intrigue me, and always have.

One thing I have found over time is conventional wisdom is usually pretty much right. On the other hand, sometimes it is bogus: you're not supposed to be able to fire high velocity cast bullet loads without badly leading your barrel and losing all accuracy. But then Tom Slater comes along and wins cast bullet benchrest competitions with cast bullets doing 2800 fps+ and group scores well below .5 moa.

And wait a minute... I'm sure most of us remember the conventional wisdom that "you can't overload a black powder rifle, the excess just goes out the end of the barrel". 30 years later, that has sort of changed...

Do I respect Green Mountain's engineering? Certainly. On the other hand, there is the little matter of legal liability and due diligence here. Not to mention that the far more likely scenario is somebody pouring 60 grains or so of rifle or pistol smokeless into one of their barrels. Even if somebody using pressure test equipment developed a "basement load" that developed no more than, say, 16,000 psi (just to use some numbers), could Green Mountain (or any other barrel maker) put anything other than "Black Powder Only" on their barrels? Not hardly.

I'm not interested in in-lines (although they are perfectly legal for hunting here and have pretty much eliminated traditional designs in this area). But then again, I'm not interested in learning to knapp flints, make a set of mocassins, etc.

That should deal with the why and background. I'm not trying to justify the "why" regarding my interest in technical issues any more than you will see me ask anyone to justify the "why" of staying with period correct firearms and acountrements.

Anyways, with the drama out of the way, it's clear that nobody has heard of anyone investigating this with a pressure recording setup. But some interesting comments did come up that were technically interesting.

The first was the strength of the sidelock design in general, along with the nipple. In one of the other threads, it was pointed out that some loads published by Lyman are in the 26,000 psi range. I don't have that newer Lyman manual, but I think it is safe to assume Lyman feels that load is safe to publish whether the reader is using a rifle with a Spanish barrel, or a rifle with a Green Mountain barrel.

Switching over to the smokeless side of things, I load a 93 grain wadcutter in my .32 H&R with 3.0 grains of Unique. Hogden says that it takes 4.0 grains to develop 19,000 psi. Certainly, much less than the 26,000 psi generated by the published Lyman black powder load.

So... putting that same load in a .32 muzzleloader... what would change the dynamics enough to turn a load that generates less than 19,000 psi in a hangun (which is not enclosed by a breech, incidentally), to one that develops more than 26,000 psi?

Black and smokeless powders do burn differently, obviously. Now... my .32 wadcutter loads have a very light crimp as that's where I get my best accuracy. I really can't say how that relates to the resistance created by a patched ball seated on top of the powder charge. That is a definite unknown.

Anyways, where and why the dynamics would differ is of interest to me, and I will investigate it once I pony up and purchase the pressure test equipment that is mandatory for anything like this.

For those interested in things like chronographs, pressure trace equipment, etc, here's a link:
CED pressure test software/hardware

 

[***Sean***]

Why??? :shake: :shake: I like the big blast of smoke out of the barrel. If you do it use a long string to pull the trigger...Make sure you are in a fox hole.

 

[roundball]

RLowe, with all due respect, this is a "Traditional Muzzleloading" site, and you did post your question in the active "Percussion" category.

If you knew all along that you were just "curious" and into experimentation for experimantation sake, then you should have posted this at the bottom of the Forum in the non-muzzleloading category.

Posting it as you did in the active "Percussion" category certainly implied your consideration of trying smokeless in "shooting percussion muzzleloaders" as opposed to running some sort of lab experiment.

While the use of some adjectives like "stupid" probably should have been left out under any circumstances...I guaged everyone's reaction as being seriously strong attempts to get the attention of someone who seemd a little too casual about his suggestion of trying smokeless powder in a GM barrel.

If you had posted your latest explanation at the beginning of the thread instead of the end, we could have all wasted a lot less of our time trying to help you.

This thread needs to be moved to the non-muzzleloading category.

 

[Leatherbark]

If I were inclined to experiment with smokeless ,I would use a very slow burner like 4831 or 7828 and use 3 grains of that before I would try Red Dot......OH and I would use a lanyard to pull the trigger and cram the buttstock down into a tire letting the barrel rest on the tire.............And hide behind a tree............And not compress the load........This is if I were inclined to try it.....
Not sure how the nipple hole would react with smokeless.......I'm sure the barrel would handle it,but its the breech end thats scary...................Bob

 

[Jäger]

I think John Taylor makes some valid points concerning the burning charactistics of smokeless powder. It requires pressure to accelerate it to a useful burning rate and the hole in the nipple may not permit enough pressure to develop to achive this rate.

I very much agree that John's bringing up the subject of burning characteristics is particularly important. The hole in the nipple certainly is a consideration - in your experience, do you think as an "escape route" it is significantly worse than the gap in a center fire resolver between cylinder and forcing cone? There is much more area available for escape in the revolver setup than there is in the area provided by the hole in the nipple. Would gas dynamics make it something other than it would seem?

Smokeless on the other hand, when subjected to high pressure, generates it's full pressure almost instantly with the pressure dropping off only as the ball/bullet starts down the bore.

On that point we'll have to disagree. I've seen enough pressure traces from my friend's equipment and commercial reproductions to know that full pressure is not reached prior to the bullet starting to move. Within the first quarter of the length of barrel, certainly, I can agree to that.

This rapid pressure "spike" has a radical effect on how the container (the barrel) will safely resist it's effects. In fact, the rapid pressure spike reduces the margine of safety by over 50%.

So... the working pressure of a barrel depends not only on its' proof, but on the pressure curve? A barrel that could safely contain 26,000 psi arrived at on a gradual pressure curve could not contain that pressure if it were arrived at by way of a smokeless burning profile?

One of the assumptions made in the original post is that the barrel is made of a comparable material to a modern smokeless rifle.
This assumption, in my educated opinion, is totally false.

I think I mostly spoke about a "quality rifle barrel" - which meant something better than the Spanish proof barrels on so many rifle. And yes, that might even be the same as barrel steel used in centerfire rifles.

Green Mountain is the only manufacturer I can quickly find which gives information on their barrel steels. They mention 4140 - which is definitely used in centerfire rifles - and 1137 which they apparently feel is good enough for sabot bullet loads in inlines. Seeing as some of the recommended sabot loads hit 25,000 - 27,000 psi, I would have to conclude that Green Mountain makes very high quality barrels. Whether 1137 steel has been used in centerfire firearms at any time, I don't know.

I think the bottom line ought to be that this has been tried many times since the introduction of smokeless powder

Now we're getting somewhere. Can you tell me where you saw the discussions or reports where somebody has tried very small charges of smokeless, and used pressure trace equipment while doing so?

Not large charges of smokeless, by accident or design, mind you. Nor even "mild" loads. And certainly not in the low proof Spanish and Italian barrels that were predominant twenty years ago.

After all, no point in recreating something that has already been tried and the data and results recorded. Just seeing the results would more than satisfy my curiosity.

It's really no different than curiosity about original formulas to brown firearms or anything else - I'm not suggesting or advocating blindly stuffing random smokeless powders into a muzzleloader or doing it in an uncontrolled fashion at the bench, without pressure trace equipment, bagging the rifle, and firing it from a distance.

 

[bradmartin]

Let me know when you are going to try this. I'll hang on to your other guns till your test is done. :winking:

 

[Jäger]

RLowe, with all due respect, this is a "Traditional Muzzleloading" site, and you did post your question in the active "Percussion" category.

Well, it is a percussion ignited muzzleloader, not an inline or centerfire, and it does involve shooting a patched ball rather than a sabot or something different, and I did see discussions of other powders other than true black powder.

However, I see your point. It wouldn't be traditional.

I guaged everyone's reaction as being seriously strong attempts to get the attention of someone who seemd a little too casual about his suggestion of trying smokeless powder in a GM barrel.

I'm not sure how a post that includes using pressure trace equipment - pretty much identical to what commercial ventures use - can be construed as being "too casual", but I guess that is all a matter of perception.

we could have all wasted a lot less of our time trying to help you.

I apologize for wasting all the time required to write the helpful posts telling me I was stupid.

This thread needs to be moved to the non-muzzleloading category.

Being as the rifle in the discussion is a muzzleloader, it wouldn't fit there either...

Actually, given the disinterest in discussing the technical issues involved and the potential for generating more heat than light in the group, probably better if you just deleted the thread, thanks.

 

[Jäger]

Let me know when you are going to try this. I'll hang on to your other guns till your test is done. :winking:

Well, you look like you live pretty close to me. If I do decide to follow through on this and come up with useable results with pressure levels everyone can agree are safe - do I get to keep your guns? We call an outcome where I come up with nothing useable but don't get a scratch on me a saw-off?

Under those conditions, we just might have a deal!

 

[Pittsburghunter]

Mr. Lowe some of the stupid comments are over board but realistly we just discuse the primative side of m/l on this sight. When we talk about other powders we talk about ones made for the sport of muzzleloading not cartridge powders.

I personally use all kinds of m/l including many inlines but curb my discussion of them and use other sites to talk about them. I personally don't agree with the use of grades of steel to discourage you from this experiment because the first cartridge rifle didn't have the modern steel used today in both m/l and cartridge guns.

The secret is the case it does the gas checking and allows the quick pressure curve talked about earlier on this thread. Even the biggest proponent of using smokeless on the web is having second thoughts about it claiming one of the smokeless rifles blew up on him.

I myself shoot enough cartridge guns that I got board and love the smoke and all even using substitute black powder. I would spend my energy if I was you doing what that green mountain barrel was designed to do make smoke!!

Yes some replies were mean instead of helpfull but remember this is a traditional site. Other replies were being helpfull with major consern for YOUR welfare and were not ment to be mean.

A final note the only m/l I have ever seen blown up was a Hawken that someone loaded with smokeless powder. It hung on the wall of Skip's gun shop in Bristol NH for about ten years till they moved.

Good luck stay safe and I hope you hang to contribute to the site but just leave the smokeless over on your reloading bench :thumbsup:

 

[mikelange]

I mentioned in my previous post about not trying to beat the demonstrated odds against something going well.

The same people who instilled that bit of wisdom in me also made it plain that I, or anyone else who was so inclined, could test our intelligence and skill against the likelihood of things not going quite right. They'd be waiting when, and if, any of us returned to report the outcome.

I didn't call you stupid. I don't have at hand any documented reports of people blowing their guns up using minute charges of smokeless. If this means that the warning I was trying to get across -- meant in the spirit of concern for your safety, not to insult you -- carries no weight, so be it. The truth is, neither your success or failure (or your living or dying, to be blunt) will amount to the smallest of blips on my radar, so -- go for it. The tone of your posts indicates you're far smarter than the rest of us, so I have no doubt things will turn out well for you.

As Forrest Gump (who's also probably much smarter than I am) said, "That's all I have to say about that...."

 

[majorinus]

Looks to me like you woke up the board...and on Superbowl Sunday! Actually, I saw a recommendation to use something like H870 or some such in black powder ca'tridges some years ago. I wouldn't want to do so in a muzzleloader, but the idea isn't as impractical as the postings would have you believe. When my father was a child--would have been in the '20s--his dad got some ammo for his 40-82 High Wall. He put it up in the barn and fired it with a string. Dad talked about watching the bullet actually hit the mountain. If you need a margin of safety there's an idea--put a barn between you and the gun.

 

[***Sean***]

Might go something like this

 

[Zonie]

Mr. Lowe: Prior to running your experiment I would strongly suggest you contact Green Mountain directly to find out exactly what steel they use to produce their muzzleloading barrels.
Although you mention 4140 (UT 117-290 KSI )and 1137 (I do not have data for 1137 however 1140 has a UT of 76-85 KSI) you should be aware of the fact that Green Mountain makes a number of barrels and many of these are intended and used for centerfire rifles.
I know for a fact that several of the better known barrel makers who produce muzzleloading barrels use 12L14 (UT 57-78 KSI)for these. By the way, the 1018 Cold Rolled Steel I was refering to above has a UT of 58-64.

I won't go further into stress analysis except to say I will stay with what I said.

Now, as many of our members have correctly pointed out, this entire Forum and is dedicated to Traditional Muzzleloading and the Precussion Forum is intended to be used to discuss traditional Caplocks.
This said, I'm sure you will understand that this post does not qualify for further discussion here.

Zonie