Very slow powders in .308

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Last Post 04 October 2016

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dbarron posted this 14 December 2015

This is my first post, although I've been a member for some time. I am wondering if anyone has experience with very slow powders in the .308 with cast bullets. I'm thinking of US869, Reloader 50, 50 BMG etc. I've tried this a little and found the results interesting. With 55 grains of US869, velocity was 2000 fps with minute of angle accuracy and no ill effects. There was significant trash in the barrel, but velocity was uniform and SD's low. Certainly no issue telling weather the case was full. Load density was 100% with a little compression. Obviously, its not the cheapest route, but.... Any thoughts?

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John Carlson posted this 14 December 2015

Now there you go again, thinking outside the box!:idea1:

If nothing else your approach ensures there won't be any double charges.

Welcome to the group from another relative newcomer.

John Carlson. CBA Director of Military Competition.

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dbarron posted this 14 December 2015

Thanks John. What box?

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mckg posted this 15 December 2015

Not the first time I hear such a report; there must be some truth in the case fill up principle.

Have you tried Blackpowder?

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Brodie posted this 15 December 2015

I have heard (read reports of) this type of load for quite some time. In the Paper Patch area especially, and for several years. Not just in the 308Win. but in the 3006, 303Brit, and yes the 3030 Win. Usually, in the 3030 it is IMR 4350 or 4831 behind a heavy (180 to 200 gr) bullet.

As I understand it the very slow powders start the bullet moving with a “gentler ” push instead of the more sudden kick one would suspect from pistol or shotgun powders. Back in the early 1970's some author wrote extensively in the Handloader magazine about using “slow” powders IMR 3031 and 4895 to get higher velocity (over 2000 fps) with gas checked cast bullets, although at the time they hadn't tried really slow powders as the OP has.

Good Luck and keep us posted on your trials dbaron. Brodie

B.E.Brickey

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dbarron posted this 15 December 2015

I've not tried that, but its a very interesting idea.

Thanks.

Don

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dbarron posted this 15 December 2015

Brodie: thanks for the info. That makes sense. Oddly, I was re reading old issues of Handloader and it was an article from the nineties by Dave Scovill that got me thinking. I'll write this up when I have some results.

Don

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tturner53 posted this 15 December 2015

A lot of work has been done using 50BMG and 20mm type powders and cast bullets. The low price of the powder got that ball rolling years ago. At one time IMR 4831 was dirt cheap surplus and was found to be useful in a lot of odd combinations. IMR 5010 was about $7 a .lb. Same as WC860 prices. I got several jugs. The unburned powder kernels are called mummies and have not affected accuracy in my experience.

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dbarron posted this 15 December 2015

thanks tturner for the info. Not much came to light on my internet search. Can you point me at any sources for further reading? Don

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45 2.1 posted this 14 January 2016

I have used the slow (for the cartridge) powders since I started hand loading cast in the late 60's. There have been several eras of powder availability starting from the old WW2 surplus 4831. All of them are useful if you treat them right. The main problem is getting them lite where they burn clean and reach proper pressure levels. To do that I duplex the charge. Doing that right takes some learning (better done with someone that is very experienced) since it consumes a lot of time and materials. Excellent accuracy can be achieved doing so though. I currently duplex the slow 50 cal and 20mm powders in a range of cartridges from 5.56 Nato to 45-70 in single shots, bolt guns and semi-autos up to 2,500 fps.

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dbarron posted this 14 January 2016

Thanks. That's interesting. What kind of velocity do you get in the .223?

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45 2.1 posted this 14 January 2016

dbarron wrote: Thanks. That's interesting. What kind of velocity do you get in the .223?

2,423 fps........ 63 gr. cast from a MP mold of my design, The fellow that was here to test it brought his chrono and DPMS AR-15 (18” barrel). 5 shots in 1.13” at 100 yards. Unfortunately, the load is somewhat dirty, unlike the one in a 6-45 AR.

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dbarron posted this 14 January 2016

Wow. That's interesting. I've been reloading for 50+ years, and have, of course, heard of duplex loads. I've used the concept with black powder cartridge loads (very cautiously) but have not tried it with smokeless. It does make intuitive sense, as the concept appears similar. I've had best luck with US 869 and 50 BMG, but the loads are, as you know, very dirty. Accuracy is good, and, as a match shooter, I'm not that concerned about velocity--not that its a bad thing. Do you know of a written source of information on the subject?

Don

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45 2.1 posted this 14 January 2016

dbarron wroteI've had best luck with US 869 and 50 BMG, but the loads are, as you know, very dirty. Accuracy is good, and, as a match shooter, I'm not that concerned about velocity--not that its a bad thing. Do you know of a written source of information on the subject?

Don I know of no known written source except for what little I've done. The 223 load has such a little case that finding the correct duplexing powder is quite ornery (either too dirty or to fast where the groups start expanding). With larger cases that is not so much a concern. The main thing is the very slow push and 33K to 42K operating pressure with full loads. I like to shoot the 308 in bolt and semi-autos. Duplexing gives quite good accuracy and very clean shooting with the very slow for the cartridge powders.

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tlkeizer posted this 15 January 2016

Greetings, Back in the mid-60's, when we shot lots and lots of prairie dogs, one of our friends in western So Dak would put his empty primed cases, either .243 or .244 whichever it was he had,, and would just pour powder into the cases until they overflowed, then shake the cake pan the cartridge holder was in, and pour powder into the cases again. Whichever surplus powder he was using had to be compressed to get a max load, so he didn't worry about it. The prairie dogs didn't seem to have a preference as the rifle and cartridges loaded that way exterminated thousands of “prairie poodles".

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tlkeizer posted this 15 January 2016

Greetings again, Oops, hit the send rather than the Preview just above. Anyway, the powder was slow enough that the loads worked fine, even though they were not cast bullets. I wish I remembered what powder and caliber combo it was, but the 60's seems to be the best decade many of us who were teenagers then don't remember very well. I think the powder was 4895 or 4831. What I do remember was father did not load his .243 that way, all loads were measured; a technique I still adhere to today. But, for a slow powder, whatever our friend used he used it very well and accurately. TK

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tlkeizer posted this 15 January 2016

Greetings again, Oops, hit the send rather than the Prview.. Anyway, the powder was slow enough that the loads worked fine, even though they were not cast bullets. I wish I remembered what powder and caliber combo it was, but the 60's seems to be the best decade many of us don't remember very well. I was also in my teens, but thiink the powder was 4895 or 4831.

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dbarron posted this 15 January 2016

So much for weighing every charge to the tenth.

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Eutectic posted this 20 January 2016

Back when 4831 was dirt cheap we tried it in everything. A case full in 30.06 or 308 worked pretty well, but the 30-30 was a bust. I had problems with the 30.06 when the weather got cold, the 180 grain cast load did not have the resistance to get combustion pressures up. I had very high velocity variations. Col. Harrison at the NRA recommended 2 grains of fast powder next to the primer. I used Unique and the problems vanished. (Yes, a dangerous duplex load) I had to dial back a bit on the 4831 for the cast loads, and Dacron filler was used to keep the powder in place. (Horrors, filler in bottle neck cases). Later I went to Grex shot shell buffer for filler, accuracy was even better. The reloading set-up was a dipper for the Unique and two powder measures first 4831 and then Grex. This load would shoot just over an inch all day long, even in rapid fire. Several other shooters tried my reloads with good accuracy. I competed against jacketed bullets with a lower velocity cast load. The local range was limited to 100 yards for most matches and 200 was big time. This saved me from embarrassing myself at long range where the cast load was only competitive in zero wind. When surplus 4831 ran out, I tried other slow powders, 5010 and H870 and others. I never had any problems as long as the case was full of something. However the results were variable. None of the slow ball powers worked well. The new (and expensive) 4831 worked, but a cast load with 4895 NOT A FULL CASE, and no fillers gave good accuracy and cost less, so the era of cheap shooting was over. Cheap 4831 and cast bullets let me shoot center fire rifle matches on a college student budget. It was fun Steve Hurst