Duplexing slow powders

[Larry Gibson]

Finding that WC 360 will be tough!

A day late and a dollar short.....the story of my life...........and now I'm dyslexic and can't type.........

Larry Gibson

[swheeler]

the only one I know that was mixing [blending] powders was Starmetal.
he never did tell me what 2 powders he was using though.

the divider paper I mentioned before is useful if your putting a fine powder on top.
it is just to stop migration.

I figured Starmetal was mixing powders, china white and crystal would have been my guess but don't know for sure?

[madsenshooter]

I was looking for the like button on that one swheeler! Guess that shows I've been on FB too much! Thanks for scientifically verifying what I already knew Larry.

[Larry Gibson]

I completed the Turk/WCC860 duplexing test a couple days ago. Based on the previously posted psi workup and projected further tests I loaded 7 rounds of 26/50 (Turk '43/WCC860), 8 rounds of 32/42 and 8 rounds of 38/36 to get a better idea of the internal ballistics and the accuracy capability. Waksupi's bullets were used and a small Dacron filler was used to assure some compression. I've no idea of the alloy Waksupi used or the PC method. He stated in a PM the bullets were "seconds".........if so they did pretty darn well.....

Attachment 196925

A before the fouling shot with the 26/50 duplex load was a wide flyer, exhibited the lowest velocity and the lowest psi. The other 6 gave an ES of only 16 fps and only 1,700 psi ES. The smooth pressure traces show it is and excellent load though we can readily see where the WWC860 "kicked in". Accuracy was excellent for the 6 shots; right at 2". Considering the muzzle velocity was 2339 fps right at the RPM Threshold for a 12" twist I'd be confident hunting with this load.

Attachment 196918

The 32/42 duplex load demonstrated excellent internals with and ES of 24 fps, and SD of 8 fps and a psi ES of only 2,600 psi. However, exceeding the RPM Threshold at 2400 fps muzzle velocity was evident because even though the internal ballistics were excellent on the external ballistic side accuracy began to suffer. The group size increased to 3".

Attachment 196920

With the 38/36 duplex load again the internals were excellent; ES of 20 fps, SD of 7 fps and a psi ES of 1,900 psi ES. The accuracy again suffered at 2.6" group given a muzzle velocity of 2481 fps but one of those shots should have been much further out to the left as I called the shot. As it was it went to the middle of the group.....that happens sometimes with ammo that produces larger groups.

Attachment 196921

Obviously many if not most of you with WCC860 probably don't have pulled down Turk '43 powder. So I ran another test using IMR 3031 and 4895 instead of the Turk '43 powder. I used a duplex load of 32/43 with each of them. The IMR3031/WCC860 duplex load performed the best accuracy wise as 9 of the ten shots stayed in 2.75" at 2395 fps which is just over the RPM Threshold. The 4895/WCC860 duplex load rand 2422 fps and the over 3" group showed it exceeded the RPM Threshold also. Neither of these 2 tests using 3031 or 4895 had the excellent internals as did the duplex loads when the Turk '43 powder was used. Their internals weren't "bad", just not excellent.

That used up all the bullets Waksupi sent me to test and all the WCC860 Bjorn gave me.

I flinched one off to the left with each of these last test loads as after 43 such 375 H&H loads off the bench I was a little "punch drunk"....felt like I'd been tag teamed by Ali and Frazier........

None the less I finished with one more test string just to test my own shooting ability, the instrumentation and the rifle's (M70) accuracy capability. Thus I let the barrel cool, cleaned it and then shot a 9 shot string of my Hornady 300 gr hunting load. This was loaded in Winchester NS'd cases, WLR primers, 78.5 gr AA4350 with the bullet seated to the cannelure groove and a crimp applied with a Lee FCD. At 2612 fps it definitely lets you know you've pulled a trigger when shooting off a bench. The 9 shots went into 1.6".....not to bad for being that punch drunk.........

Attachment 196924

Larry Gibson

[Ricochet]

I am working with duplexing WC860 and a couple of .223 appropriate powders, one the old Hi-Tech "PSA" that was sold with the advice to use 3031 data and said to be Chinese made Accurate 2230 rejected because Accurate forgot to tell the Chinese in the contract that it should have flash suppressant, and milsurp WCR845. I load some cartridges like .30-06 and .22-250 in which the WC860 is much too slow to reach full working pressures for J-bullets and the .223 powders are pressure limited with around 2/3 case capacity filling and a bit less than "standard" velocities. I started with the idea I'd read for years here of thinking of the slow .50 caliber and 20mm powders as "reactive filler," realized I would have to substantially reduce the faster powder charge to fill the empty space and keep pressures safe. I take a different approach of starting with a case full of the slow stuff, check the velocity with a Chrony, and then start with replacing a SMALL amount of the slow powder with the faster powder, and rather than follow the old idea from black powder practice of putting the "booster" powder in the bottom of the case over the primer, I put it in the top of the case right under the bullet. Light to moderate compression holds it in place. My thinking on this is that the slow powder gets a head start on ignition with the primer flame first coming directly into it, it is burning away its deterrent and building pressure toward the shot start point as the flame is filtering through the porous powder mass to ignite the faster powder just as the bullet starts to move. It is more of a progressive burning arrangement than lighting the fast powder first, and as the bullet moves out of the case the fast powder is the first to follow it into the expanding bore space. That makes more sense to me than having it at the bottom trying to jam the unburned slow powder through the case neck. As this is work in progress, very much experimental, I am using nonstandardized powder lots, and I have no way of quantitatively measuring pressures, I won't share any actual loads. But you would be surprised at the velocities a compressed case full of WC860 will give by itself, and with how little of the "booster" makes a lot of difference! I am not using powders of hugely different burning rates like pistol powders, but rifle powders a little too fast to be ideal for the cartridge and bullet combination as the "booster." I start small and increase slowly, watching the velocity and examining cases and primers for signs of excessive pressure. I am well aware of the warnings about noncanister grade powders and mixing powders. I am not advising anyone to do what I am doing. You can indeed wreck your rifle, and possibly seriously injure or kill yourself if you are careless. But it can be done safely, if done thoughtfully and carefully.

[waksupi]

I am working with duplexing WC860 and a couple of .223 appropriate powders, one the old Hi-Tech "PSA" that was sold with the advice to use 3031 data and said to be Chinese made Accurate 2230 rejected because Accurate forgot to tell the Chinese in the contract that it should have flash suppressant, and milsurp WCR845. I load some cartridges like .30-06 and .22-250 in which the WC860 is much too slow to reach full working pressures for J-bullets and the .223 powders are pressure limited with around 2/3 case capacity filling and a bit less than "standard" velocities. I started with the idea I'd read for years here of thinking of the slow .50 caliber and 20mm powders as "reactive filler," realized I would have to substantially reduce the faster powder charge to fill the empty space and keep pressures safe. I take a different approach of starting with a case full of the slow stuff, check the velocity with a Chrony, and then start with replacing a SMALL amount of the slow powder with the faster powder, and rather than follow the old idea from black powder practice of putting the "booster" powder in the bottom of the case over the primer, I put it in the top of the case right under the bullet. Light to moderate compression holds it in place. My thinking on this is that the slow powder gets a head start on ignition with the primer flame first coming directly into it, it is burning away its deterrent and building pressure toward the shot start point as the flame is filtering through the porous powder mass to ignite the faster powder just as the bullet starts to move. It is more of a progressive burning arrangement than lighting the fast powder first, and as the bullet moves out of the case the fast powder is the first to follow it into the expanding bore space. That makes more sense to me than having it at the bottom trying to jam the unburned slow powder through the case neck. As this is work in progress, very much experimental, I am using nonstandardized powder lots, and I have no way of quantitatively measuring pressures, I won't share any actual loads. But you would be surprised at the velocities a compressed case full of WC860 will give by itself, and with how little of the "booster" makes a lot of difference! I am not using powders of hugely different burning rates like pistol powders, but rifle powders a little too fast to be ideal for the cartridge and bullet combination as the "booster." I start small and increase slowly, watching the velocity and examining cases and primers for signs of excessive pressure. I am well aware of the warnings about noncanister grade powders and mixing powders. I am not advising anyone to do what I am doing. You can indeed wreck your rifle, and possibly seriously injure or kill yourself if you are careless. But it can be done safely, if done thoughtfully and carefully.

Interesting! I've often wondered if people are too concerned about fast and slow powders mixing in duplex loads.

[cainttype]

If "someone" with the proper equipment ever had the chance to do pressure testing on duplex loads like Ricochet is experimenting with it would certainly be of interest to those of us who have to guesstimate such things...
A direct comparison of known "booster" charges loaded directly over the primer or over a caseful of the same slow ball would be really nice. I know I've never seen such data, but would definitely ear-mark it for future reference.

[Larry Gibson]

Interesting! I've often wondered if people are too concerned about fast and slow powders mixing in duplex loads.

You can blend powders of the same type and size successfully; ball with ball, extruded with extruded and flake with flake. Ammunition factories do this often blending various small different lots of the same powder thus creating a large new lot. They then develop the load with that new lot.

I have done the same. Years past when moving to a different location I had several partial cans of BLC2, BR748, H335 and pull down 5.56 and 7.62 Nato powders. I poured them all into a large plastic bag and mixed thoroughly. I came out with just under 8 lbs of powder. I then worked up a load for it in my M700V .223 Rem under 55 gr SX bullets. The load selected has been a consistent 1/2 moa performer. I have pressure tested that load and it is right at the SAAMI MAP for the .223 rem and gives excellent internal ballistics. I have about 2 1/2 lbs left and am going to cry when it's gone.......as I'll never be able to duplicate it........

I have also blended numerous different pull down 4895s from numerous different 30-06 rounds into one "lot" of powder, then worked up a load for that lot with excellent results.

However, the problem with blending powders of the same type but different size and considerable different burn rates (i.e.; H4831 and H4895) is ensuring a consistent blend throughout the mixing and loading process is very difficult. The same is true of blending different types of powders (i.e.; flake with extruded). Powders of different sizes and different types tend to separate from each other. especially when jostled such as in loading, transporting and handling. The powders separating out can have completely different burn characteristics from their properly blended counterpart.

The trick to blending is to use powders that will blend together evenly and do not separate apart once blended, to blend a large enough amount that the created lot of powder is a useful amount or to use powders that are readily available so with the know percentages the blend can be duplicated.

Larry Gibson

[waksupi]

You can blend powders of the same type and size successfully; ball with ball, extruded with extruded and flake with flake. Ammunition factories do this often blending various small different lots of the same powder thus creating a large new lot. They then develop the load with that new lot.

I have done the same. Years past when moving to a different location I had several partial cans of BLC2, BR748, H335 and pull down 5.56 and 7.62 Nato powders. I poured them all into a large plastic bag and mixed thoroughly. I came out with just under 8 lbs of powder. I then worked up a load for it in my M700V .223 Rem under 55 gr SX bullets. The load selected has been a consistent 1/2 moa performer. I have pressure tested that load and it is right at the SAAMI MAP for the .223 rem and gives excellent internal ballistics. I have about 2 1/2 lbs left and am going to cry when it's gone.......as I'll never be able to duplicate it........

I have also blended numerous different pull down 4895s from numerous different 30-06 rounds into one "lot" of powder, then worked up a load for that lot with excellent results.

However, the problem with blending powders of the same type but different size and considerable different burn rates (i.e.; H4831 and H4895) is ensuring a consistent blend throughout the mixing and loading process is very difficult. The same is true of blending different types of powders (i.e.; flake with extruded). Powders of different sizes and different types tend to separate from each other. especially when jostled such as in loading, transporting and handling. The powders separating out can have completely different burn characteristics from their properly blended counterpart.

The trick to blending is to use powders that will blend together evenly and do not separate apart once blended, to blend a large enough amount that the created lot of powder is a useful amount or to use powders that are readily available so with the know percentages the blend can be duplicated.

Larry Gibson

I should have known you had examined this.

Only allowing same powder types to be mixed would be instinctive to me. It would give me the heebiejeebies to mix stick and ball, and expect consistent (and safe!) results.

Once again, Larry, you da man!

[Ricochet]

My load development process is simple. I have chronograph data from maximum safe loads with "normal" powders in my rifle with its caliber and the bullet. That's a target velocity I hope to match and won't likely exceed. I have one powder that's so slow it can't be overloaded. A compressed case full will give pressures and velocities well below standard levels. The other powder is a little fast for that cartridge and bullet, reaching maximum safe working pressure with the case 2/3 to 3/4 full. A compressed case full would at least be a hot proof load, and might grenade the rifle. It stands to reason that if some of the slow powder is taken away and replaced by an equal amount of the fast one in small increments, at some proportion it will just reach maximum safe pressure. The trick is to start with a very small amount of the fast stuff and increase a very little at a time. I use the classic methods of observing signs of pressures as developers of load manuals did in my youth, and for my rifles I can be confident that a load is safe if the brass isn't overstressed. But I would love to see someone do this with modern piezoelectric pressure measurement with pressure-time curve tracing!