Theoretical Question: Duplex loads
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Russt
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I don't load duplex loads in my 45/70 but the Lyman Cast Bullet Manual shows a few duplex loads only in the Ruger #1 & #3 section. They show 6.0grs of SR4759 under 56grs of FFg for 1259fps. A MAX load of 7grs SR4759 and 63grs of FFg. That shows a compressed load. Pressure is only 18,700 for a MAX. I don't know the reason for a duplex but I'd guess it is to get all that black to burn cleaner. Sounds like a mess to me, but I don't shoot black powder because I don't want to deal with the clean up.
I use SR4759 as a reduced load. I was told it was to mimic the old black powder loads with out the mess. I like IMR 3031 for most of the loads in the 45/70, 51grs of it with a 300gr JFP is very accurate at 100yds.
I use SR4759 as a reduced load. I was told it was to mimic the old black powder loads with out the mess. I like IMR 3031 for most of the loads in the 45/70, 51grs of it with a 300gr JFP is very accurate at 100yds.
In my 45 x 3-1/4 I use ~8gr IMR4759 under ~90gr 1F black, under a 3/16" grease-soaked felt wad (50/50 Crisco/Alox) under a milk carton/bar-coaster disk, topped off by a paper-patched (2x wrap 25% cotton unionskin) 600(+)gr pure lead Ballard dropped from an adjustable mould. The powder column is vibrated down for compaction to make this a "tight" load, not a compressed one.
The rifle is one of Wolfgang Droedge's original Shiloh's out of Farmington back about 1981 or so, and I spent the better part of an empirical year & a half finding out what it liked to shoot. The combination you see above is it, ...particularly as the paper-patch likes the slightly cleaner burn & barrel that the duplex provides. 1-1/4" reliable MOA.
The rifle is one of Wolfgang Droedge's original Shiloh's out of Farmington back about 1981 or so, and I spent the better part of an empirical year & a half finding out what it liked to shoot. The combination you see above is it, ...particularly as the paper-patch likes the slightly cleaner burn & barrel that the duplex provides. 1-1/4" reliable MOA.
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sonier
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I know one DARN good reason for a duplex load already, My 357 magnum, i loaded about 200 158 grain leadcast under a slightly compressed load of BP, one year later............. I found a few of these cartridges, and they had a 50% failure to fire, the smokeless will burn so hot that even if the BP is wet, it should still fire, and not hangfire as well.
Good information.
I do not have access to SR/IMR 4759 only VV powders. I am assuming that 4759 is a slow burning powder.
I have noticed hang fire's in my 45/70 with BP in particular. I wonder if these types of loads would improve things.
After firing BP I normally fire a couple of smokeless loads to get the majority of the crud out. Seems to work fine. Also I dont wash my barrel, just use KG-1 and havent had any issues so far.
I do not have access to SR/IMR 4759 only VV powders. I am assuming that 4759 is a slow burning powder.
I have noticed hang fire's in my 45/70 with BP in particular. I wonder if these types of loads would improve things.
After firing BP I normally fire a couple of smokeless loads to get the majority of the crud out. Seems to work fine. Also I dont wash my barrel, just use KG-1 and havent had any issues so far.
IMR's SR4759 is bracketed by N110 (faster) and N120 (slower) for burn rate.
Normal duplex ratios are 5-10% of the standard black charge.
(Need I say to start low?)
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Do NOT use duplex loads in rolling blocks/trapdoors, etc.
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If hangfires are your BP problem/reason for duplex'ing, have you tried magnum primers first?
Normal duplex ratios are 5-10% of the standard black charge.
(Need I say to start low?)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Do NOT use duplex loads in rolling blocks/trapdoors, etc.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If hangfires are your BP problem/reason for duplex'ing, have you tried magnum primers first?
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Jim Watson
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Hangfires and misfires with black are very strange, I have never had one or seen it on the BPCR firing line. Many shooters have backed away from magnum primers, looking for milder ignition. Some have gone to pistol primers, some put paper wads over the flashhole to soften the flame.
NRA no longer allows duplex loads so I have no background or sources for them.
NRA no longer allows duplex loads so I have no background or sources for them.
sonier
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Ive tried magnum and normal pistol, some how the BP powder wicked in moisture most likely, but a duplex load would ensure a fire.
My .45-70 is an Armi Sport falling block. So unlikely that I will be trying duplex loads. Will try both Magum and Pistol primers first. There seems to be a very slight hangfire with the BP cartridges. I currently am using Swiss 3FG BP because that is what I have on hand.
That is the Sharps design?
http://www.google.com/imgres?imgurl...ort+falling+block&hl=en&sa=G&gbv=2&tbs=isch:1
If so that's a very strong action, totally beyond inherent trapdooor/rolling block weaknesses
http://www.google.com/imgres?imgurl...ort+falling+block&hl=en&sa=G&gbv=2&tbs=isch:1
If so that's a very strong action, totally beyond inherent trapdooor/rolling block weaknesses
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