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Duplex and Triplex loads

I read this topic with interest and couldn't help but think as soon as someone does this and wins a match there will be another 100 people doing it since "so and so" did it and won.

"It much be the best thing"

SDH
 
SongdogHunter said:
I read this topic with interest and couldn't help but think as soon as someone does this and wins a match there will be another 100 people doing it since "so and so" did it and won.

"It much be the best thing"

SDH
Click to expand...

This practice has been in existence for MANY years, but most shooters still won't try it as is evidenced by this thread. I'm not going to advocate it, but it can be done safely by the VERY experienced reloader. I don't agree with the opening post that most of the top shooters do it, but some do.
 
Curiousity was my reason for trying it.

Using a 260 with 139's, AA Magpro was about the only choice for a ball powder that filled the case. And fill it it did. 49 grs netted 2860 fps without pressure.

My starting charge with Magpro only, was 45 grs which gave a very slow, but very accurate, 2585 fps.

I decided to keep the charge weight at 45 grs, but combine some H414 with the Magpro. I started with a 1-8 ratio of 414/Magpro and went all the way to 50/50, but all the while keeping the charge weight at 45 grs.

Ending velocity was 2930 fps without pressure, and accuracy was very good.

I had thought of going to a faster ball than 414 but thought where I ended was pretty good.

I really did not have a good reason for trying it other than everyone said not to, which is not a good reason, but hey, I am a tinkerer. Ball seems to suffer badly from chamber heating compared to stick powder, and shooting to 1k you will have a good deal of vertical from it.

Have not done the same test in the 260AI. It's velocities are good enough from the start.
 
B

Interesting experiment.

I really like your reasons for doing it. You sound a lot like me. Hmmmmm, I wonder if . . .

How did you keep the ball powders from mixing inside the case? During WWII the Germans experimented with duplex loads but, of course, a military cartridge is subject to a lot of jostling and they had to abandon the idea because they couldn't find a good way to keep everything seperate.

Thanks for posting.

Ray
 
The first test was with putting the 5 grs of 414 on the primer, and then dumping the 40 grs of Magpro on it, vs. mixing it together from the get go. No difference in velocity.

I did put the 414 in each case first, then the Magpro on top. But in traveling to the range, I am sure they mixed themselves.

I don't think it makes a difference, but I could be wrong.
 
There is a lot of stuff on the web about sifting gunpowder. If the factories are mixing powders to get a burn rate, and they probably are, then this would indicate something of the proportions. We don't know what the tolerances are on the grain sizes so sieving the ball powders might not get you exact proportions.
 
There have been several post over the last couple of years with rifles opened up with split barrels and actions. Twice I can remember reloaders having changed powders without emptying their measure and re-calibrating. The measure may have had a small amout of powder A and was refilled with Powder B. The the big bang occured. This could be due to a number of factors such as mixed load or just an over load. The end result was still a disaster. I have no problem mixing two lots of the same make and same powder. I have big problems with mixing two different powders trying to acheive a new burn rate or presure curve. I have long suspected that one manufacture who loads "light magnum" loads uses some form of propriatary combination of compressed and or duplex loads. They have the laboratory and methods to test with such.
Rustystud
 
wasn't there a guy At PA 1000 that had a gun blow up in a match using triplex loads, I talked to him when I was up there the 1st time 1987 he had a missing finger and the bolt took off part of his ear, he was in the years at that time so I'm sure he has passed,
 
I've seen duplex loads being a very common thing in the world of smokeless muzzleloaders but not in standard centerfire cartridges. To be honest, I'm not sure I'd want to try it with any sort of centerfire case.
 
Given how many powders exist, I'm not sure I see the point. I'm sure it could be done safely, but you're flying blind, which is probably a bad idea. If there were data available and the behavior were understood, then sure. But we don't know, and it's not like its hard to find a powder that's a little faster or slower. I, for one, am not going to be the pressure test. I'll leave that to the professionals.
 
As an avid smokeless muzzle loader shooter, I shoot duplex loads, with no issues. We do the layering method. I use Red Dot under H4198 to push a 327 grain Parker Match Hunter at 2600 fps. Do NOT do this with a standard muzzle loader,This is a custom rifle, 700 action with a Pac Nor barrel and special breech plug. It is 45 cal and we shoot bullet to bore. These guns will out shoot most deer rifles. Lots of info on this over on Doug's Message Board. Also, visit Arrowhead Sporting Goods. Luke is a great resource.
 
Ive seen a number of black powder guys using Unique or other similar powder under black powder loads. The general comment is that it keeps the bore more clean. Whether by ensuring better burn or “blowing the crud out”, I don’t know. I’ve used Unique for light loads in a 45-70 and could see how “adjusting the pressure curve” of a powder for over bore magnum cartridges where a lot of very slow powder is needed and large bore rifles where the pressure building characteristics may not perfectly match what fits in a case.

All of that said, I think with today’s powder choices which tend to be tailored to particular cartridges/cartridge types, there’s probably not that much to be gained from duplexing today......unless I’m using my 45-90 in a 100 yard benchrest match I guess. Doubt the other guys would appreciate the black powder smoke while they’re trying to speed shoot their target to catch a condition. ;-)
 
Isn't here some mention in the results of VV131.5 or something like that where 2 VV powders are mixed?
 
I have a vague recollection of duplex loads being used with the .454 Casull to achieve design parameters, I imagine a faster powder over the primer to ignite some overpacked ( sorry, compressed) load of something slower. ( coal or sawdust?) I may have dreamed this in a an alcohol induced coma - so I'm not advocating it or even going to try it!
 
I have talked with some guys who used to shoot revolver competitions that did duplex and triplex loads in the big 44s and 454s.

I shoot a smokeless muzzleloader too. As noted above I have some duplex loads with a few grains of a fast powder on the bottom get a whole lot of a slower powder on top the idea being that the fast powder spikes the pressure so you get a good burn.

With all of the powders available today for bottle necked cartridges I don’t think it’s necessary
 
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