I have wanted to try duplex loads for a while and after following this thread and reading what else I could find I gave it a go. I load a paper patched boolit over a lightly compressed load of 2F for a .38-55 rolling block. Yes I know 3F would be better but 2F is what I have. Anyway I loaded 4 grains of 2400 in first and then the 2F as usual. No reduction for the 2400. I assembled just 10 rounds mostly to check for excess pressure and experienced none. There didn't seem to be a lot of fouling but it was only 10 shots. I will be experimenting further.
The primary issue with both flinters and caplocks is that the ignition system is not up to the higher pressures of some of the smokeless powders. Second is the materials used in barrel construction tend to have significantly less hoop strength than steels used in most smokeless guns.
In the early days of semi-smokeless and smokeless they sold "bulk" powder to be used as a one-to-one volume black powder replacement.
Blackhorn 209 is claimed to be a smokeless powder with a little smoke added.
2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
"Before you argue with someone, ask yourself, is that person even mentally mature enough to grasp the concept of different perspectives? Because if not, there’s absolutely no point."
– Amber Veal
"The Highest form of ignorance is when you reject something you don't know anything about".
- Wayne Dyer
I have seen it done a few years ago by Iraqveteran8888. They kept going with straight smokeless powder loads until they blew it up, but those loads that caused failure would have likely blown up a modern cartridge gun if one could have gotten that amount of powder into the gun. They did not use a pressure transducer. I have no idea at what pressure the barrel will fail at for modern steels and that question of also for the older BP cartridge guns.
They kept warning not to use smokeless and duh eventually the gun blew up.
Just for my own information I will look up that old youtube to see what charge made that side cap lock gun fail.
Are the steels used today for muzzleloading guns inferior to what is used in modern cartridge guns. I have not been able find any specs for this and for modern barrels I have no idea what hoop strength might be. Both flinters and caplocks have a hole going to the outside and I can see safety problems. But are duplex loads used of 10% or less of smokeless/black powder so high pressure that the lock or barrel will fail?
Look someone puts in an 80 grain load by bulk of 2400 in a 54 cal cap lock gun and it is likely coming apart, but so would your magnum Weatherby. Basically I will not be trying such by myself, but would like to see someone investigate it.
my previous posts should tell that I am not a "fraidy cat" or negative to duplex loading in its appropriate place
however I reckon there are a swag of more practical, more effective, much safer, ways to handle a fouling problem in muzzleloaders than fooling around with duplex smokeless/blackpowder loads.................round ball guns are the easiest ...I have a target on my wall shot at the Canberra range years ago 100yards, sitting position with a CVA flinter, 42" barrel, the first five in a group 2"x2" ..the second five in a ragged conjoined hole that went a tad under 1"x1" ....I could see those days and I was shooting pretty good and (often) - the load was so simple 70 grains of Goex 5FA - 490 ball - damp moosemilk ticking patch. just load em and shoot em no foolin about.
for the long boolit still plenty options, decent lube , card wad on the powder + damp felt wad, none of em any more complicated than loading two different powders .............................
Most modern cartridge gun barrels today are 4130, 4140, 4150 or 4340 chrome molybdenum alloy ordinance grade steel if blued. Most of the SS barrels are 416 or 416-R ordinance grade stainless steel. Lothar Walther made the barrels for Black Star. Claim was it was a different alloy but I never could find out what it was.
At one time the majority of modern muzzle loading barrel producers use 12L14. Not sure if that is still true today. I do know 1137MOD steel is popular today.
12L14 is a leaded free machining steel that does NOT provided very high hoop stress strength. Hoop strength is the measure of a pressure vessel to withstand the internal pressures. This first came to be a big deal when steam engines switched for low pressure to high pressure designs.
One other issue with using non-ordinance grade steel for barrels is slag inclusions and or sulfur content.
Unless specifically designed for smokeless it generally is not a good idea to use smokeless in a muzzleloader. There are SOME smokeless powders that have a pressure curve similar to BP and they have successfully been used in BP muzzleloaders. That was far more common in the 60's and 70's pre-Pyrodex.
The issue is smokeless powders in muzzleloaders tend to not be very tolerant of mistakes like leaving a ramrod in the bore or a double charge.
BP as an ignition aid under Blackhorn 209 works well and appears to be safe.
Last edited by M-Tecs; 10-06-2023 at 03:13 AM.
2nd Amendment of the U.S. Constitution. - "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
"Before you argue with someone, ask yourself, is that person even mentally mature enough to grasp the concept of different perspectives? Because if not, there’s absolutely no point."
– Amber Veal
"The Highest form of ignorance is when you reject something you don't know anything about".
- Wayne Dyer
If you load a muzzleloader clear to the muzzle with black powder it will blow . The weight of the powder it self would be the culprit. Muzzle loading barrels are made from 12L14. Soft stuff that was never intended for firearms, but it works fine for the low pressures rational loads of lack powder creates. 1130 is used by green mountain for their muzzle loading barrels. Kibler uses green mountain blanks. Hoyt, Burton and Rice use 12L14. Getz did too. Ed Rayle uses some sort of modern barrel steel that is so hard it's difficult to file.
Your suggestion is not offered in a friendly way and to be courteous as we are supposed to be here I will offer no counter suggestions. The point is there are all sorts of urban legends and half truths on the net and I am just trying to get find out the truth. You made a statement and I asked for evidence. You could of answered honestly that you knew of none.
But many urban legends do have at least some truth associated with them. There are plenty of people that blow things up and video it. I have only seen one with a side lock muzzle loader and it seemed that within in reason that it was safe.
As they say, do not do this at home.
The h 209 powder seems interesting.
This maybe a dumb question, but I'll throw it out since this a duplex thread.
Could one use a few grains of 4227 over black in the loading of a Burnside catridge? Or a Maynard?
Both use an enclosed case, but a flash hole in the rear.
Just curious if anyone has, or if it would benefit less fouling.
The main idea for the duplex cartridge is for the small smokeless charge to blow the charcoal residue out of the barrel. When developing the load, you can actually see [by looking in the bore from the breach end] how much of the charcoal residue has been blown out. Refer you to Spence Wolf's book on replicating 45-70 M1873 loads for the "how to".
Larry Gibson
“Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
― Nikola Tesla
not arguing yes or nohere but offer a story
I have three post hole guns different lengths designed for blasting grade blackpowder (about quarter inch gravel size grains) the powder chamber in the longest one is about 15 - 18 inches x 1 inch (it is a glutton for powder!!!!!) there is a nipple at the top end of the powder chamber and most of a foot of solid shaft above the nipple - these are designed to be filled to the end with powder - you cap it with a half handful of dirt to stop the charge from falling out then proceed to whale on it with a 12 pound sledgehammer till its right down in the ground where you want the hole - driving one of these into hard ground can take a while - I normally use the shortest gun but this particular day it was broken (stress fractured from all the hammering) only had one hole to make so took out the big long gun, but being cheap and almost out of blasting powder I elected to half fill the chamber then fill the remainder of the charge chamber with dirt (BIG mistake) then belted it down into an old roadway near the shed. I had used this dirt cannon plenty of times but this day with the half charge and plenty of constriction to hold it in that thing blew the nipple clean out of the metal body just shredded fibres of steel where it used to be - the nipple was airborne long enough for me to figure something wasnt right, walk over to the site puzzle a little then clunk!, tinkle tinkle plop - it landed on the shed roof, rolled off and landed where I had been standing --- have no idea of the pressure involved but an engineer bloke I showed it too guessed in excess of 100.000psi.
All that to say I would feel safer (I think there would be less pressure) with the barrel full of powder and the ball at the end compared to a half full barrel -----whatever ----not about to make a utube video to investigate the theory
Friendly way? If you won't listen to me you're free to do what ever you like. I personally don't care and assume no responsibility for your actions. You're a big boy, go against My recommendations if you think you know more about it than I do. How can I be more courteous than telling you to do what ever you think is right.
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |