Money In, Money Out
on 06/15/2010 at 03:23 PM
Ah-ha! More handloading stuff!
I bought - but have not yet read - the two books you recommended last time: the paper patch book (which looks fascinating!) and the “any load you want” book.
I’m looking for a book or article on multi-powder charge techniques. Suggestions?
Oh - and I’ll be stealing that O’Dingus moniker. Well spat, Sir!
I prefer Президент Оба́ма myself. Dirty Fuckin’ Communist that he is.
Multi-powder charge technique suggestions?
Sure:
1. DON’T DO IT. EVER. BAD DOG. BAD DOG! You can almost always find a powder better suited to your needs. Try using hotter primers first, like the Winchester Magnum Rifle. Back your loads off 5% when switching to a new primer and work up in 0.5gr increments.
2. Do it only for black powder loads using cases that do not have an enlarged flash hole.
But gee, slightly enlarging the flash hole makes my BP charges burn cleaner anyway! Exactly: see suggestion #1.3. Do it only when you are using loads of at least 100% density. If your charges are not a bit compressed then the powder can move around in the case. This movement will eliminate the reason you did a multi-powder (aka duplex) load in the first place (a little fast burning powder to help light off a lot of slow burning powder). Besides, almost all BP loads benefit from a bit of compression.
4. Unique and SR4759 seem to be the powders of choice. In his book Forty Years With The .45-70 Paul Matthews found that about 13-15% duplex loading eliminated almost all fouling and gave a clean burn. The BP in those loadings was reduced by the appropriate ratio! You CAN NOT just take a full BP charge and toss a few grains of Bullseye, Unique, Clays et al in the bottom of the case and expect anything other than an EXPLOSION IN YOUR FACE.
5. See suggestion #1. See it again. And again. Duplex loads are inherently dangerous and should only be approached - with extreme caution - by those who have been so deep into reloading, shooting, wildcat development, smokeless and black powder work, etc that they can tell the brand, style, and charge of powder the guy on the next bench over is using merely by the taste of the smoke. And it doesn’t count if you can do this for WW296: everybody knows that one by taste, sound, and muzzle flash. And the cough you have the day after.
6. Duplex loads should only be used in rifles of grossly sufficient strength. Just in case. Your Contender is not strong enough. Nor is any original black powder firearm. Nor is a SMLE. A Ruger #1 is strong enough, and so is a Weatherby Mark V. Too bad that those rifles are only chambered in 1 or 2 cartridges appropriate for BP use.
7. Buy Matthews’ other book, read what he wrote, read it again, and realize that those loads were producing at most 34,000psi and probably less. There is no reason on earth that duplex loads are necessary for any fully smokeless loading that produces modern rifle pressures in the 35,000 - 65,000psi range. If you aren’t getting an amount of burn you are happy with, find another powder. Load development is ALWAYS a trade-off and a balancing act. A somewhat lighter charge of a slightly faster powder will usually burn cleaner at the same pressure point, but will result in a bit less velocity. A given charge of a slower powder behind a lighter bullet that creates a pressure peak WELL WITHIN safe bounds but that doesn’t seem to burn well will almost always burn better and produce better velocity with a somewhat heavier bullet. Somewhat! Substituting a 700 grain monster for a 55 grain midget and using the same powder charge is a recipe for GUARANTEED SUICIDE. See suggestion #1.
8. Has my response frightened you? I hope it has. Don’t mess with duplex loads unless you are a serious expert. And even then, know when to say when, and that’s after just a tiny tiny bit and only in the right kind of gun and only with the right kinds of loads and only when overall pressures are relatively benign to begin with and only when you have the good sense to study the hell out of it ahead of time. In other words, see suggestion #1.
So...you’re subtly hinting that there might be a potential particle of risk associated with duplex (that’s the word I was looking for!) load development?
You don’t say!
I’d read about them in an old reloading book (Wile Clapp rings a bell, but then so many names do.). He kept the various charges separate inside the casing with some kind of inter-charge wadding. Also, shaking up loads vigorously was frowned upon.
I also recall that the intent was to achieve a consistent FLAT pressure front presented to the ass-end of the round going down the barrel. But its been 15 years since I read it. I’ll try to dig it up.
He was talking duplex and even triplex loads. I never saw any result data.
I like the flat front idea, because the result is an enormous increase in velocity with no increase in pressure. Just the same pressures sustained for longer. Rather like the thrust curve of a C6 engine compared to that of the B6 engine for all of you who grew up with Estes rockets: same overall peak spike, but far more area under the curve. The problem is that you actually need something close to an end burner rocket engine to do that; it’s close to impossible when the charge stays back in the cartridge case. Especially given the volumetric dynamics: You need about 2000 times as much gas to keep pressures constant when the bullet is out near the muzzle compared to when it’s just starting to leave the case.
One approach would be to build a reverse primed cartridge ... something like this was done in the very early years of cartridge development ... Germany ... the Dreyse Needle Gun. It put the primer at the base of the bullet, on top of the powder charge. Ignition lit the powder from the top, not from the bottom as we do it today. That way you could use enormous charges of slow, gas rich powder, and not need a primer the size of a Teller mine to light it off. Of course there were several major shortcomings to the Dreyse rifle ... gas leakage, short firing pin life, constant misfires unless the parts were lined up perfectly, poor ignition because the whack of the firing pin drove the bullet forward a bit and thus created an air gap between the BP and the primer flash, etc.
That reverse primer idea is complicated enough to be a bit scary, too! The things folks have tried in the past!
Your Estes analogy is perfect! And you’re right: filling a barrel with pressurized gas “just right” to produce a flat front would be virtually impossible, I think. I wish I could see any data the old-timers took (if any) to see what kind of results they got.
BTW: In spite of my seemingly making light of it, you’re “bad dog” comment was truly taken to heart - not that I needed discouraged. There ain’t no way I’m messing with duplex or triplex loads. Momma didn’t raise a complete fool. When I can outshoot even one of my own weapons - i.e. can shoot better than the weapon can perform - then I’ll worry about such tiny esoterica as flat-front internal ballistics. I’m still working on punching only one hole in the target.
Me too! But half the fun of messin wit gunz for me is this kind of esoterica. They are simple machines, but what goes on inside them in a time equal to less than 1/5 of the blink of an eye is complicated and nearly magical.
Oh, and I like the ones with pretty wood and highly polished and blued metal. Kind of like deadly furniture in a way.
Crapz. The a/c recharge lasted all of one day. That means I’ve got a leak under there somewhere. $$$.
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