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Old August 29, 2012, 10:58 AM   #1
Pond, James Pond
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Morphing powder. Wassit mean?!

Today has been a day of revelations in my expanding world of reloading.

Firstly was that whatever measuring disk I choose, my Lee Auto disk pro will conspire to give me precisely 0.2 gr less than I want.

Then there was the fact that, once I've primed cases, I put out about 150-200 finished cartridges in an hour..

After that came the fact that I can throw an hours worth of reloading down range in less time than it took to load it.

And finally, the reason for this post. The following only happens (as far as I can see) when shooting my reloads out of my 2" snub. The reloads are 5.8gr of N350 out of S&B cases with CCI small pistol magnum primers all sat under a 125gr plated bullet from H&N Sport.

I shoot. There is a bang and a hole in some paper. However, when I eject the cases, I find that there are a dozen or so grains (as in pieces) per case of orangey-yellow pellets. If they were graphite grey, they would look like N350. I've cunningly deduced that this is still N350, but after exposure to heat and pressure.

What does having this seemingly unburnt powder tell me about my reloads anf the conditions in the chamber at the time of firing?
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Old August 29, 2012, 12:08 PM   #2
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Your powder is too slow to burn up in that short barrel. Common snubby problem. If you have a chronograph you discover the velocity spread is high, too. I've seen up to 25% ES.

At the other extreme, N310 will burn clean as a whistle and give much lower MV spread, but you will lose velocity because you can't safely use enough of it to go as fast. You could try N320 or N330, too. Peak velocity at safe pressure will go up, but so will fouling and velocity spread.

I don't have numbers for VV, but all powders have some bulk density tolerance. Lee's VMD's are taken from samples they bought, but due to the lot variations they are almost never exactly what you have. On this side of the pond only Western Powders publishes average bulk densities and gives tolerances, which vary by powder quite a bit and don't match Lee's numbers well in some cases. (see below). So keep on with the cut and try approach to landing a charge weight.

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Old August 29, 2012, 03:02 PM   #3
Pond, James Pond
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So keep on with the cut and try approach to landing a charge weight.
Thanks for a very detailed post with lots of info! I confess that most of the info goes way over my head:
Terms like ES, MV, VMD, bulk density tolerance and velocity spread to name but a few.

The first problem I envisage is that if I have to much powder to burn in snubby at this, the starting charge for this load, I can't very well, drop below that starting charge. They all say that is bad practice!!
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Old August 29, 2012, 03:38 PM   #4
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Yep... such a massively incomplete burn, that the granules remain.

I encountered the same problem with Lil' Gun in a small cartridge, a few years ago. Except, the Lil' Gun granules were fusing together, into a single mass. I just had to touch the mass to get it to break loose from the case wall, and the single chunk would fall out of the case.
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Old August 29, 2012, 08:18 PM   #5
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Mr. Pond,

The orange particles that you found were indeed granules of N350 after being exposed to heat and pressure. Basically, the primer ignited those granules, and the outside layer with the graphite coating burned away, but the powder stopped burning when the bullet left the muzzle and the pressure dropped. If you had put a white bed sheet on the ground out in front of your muzzle, you would have found many more orange granules out there on the sheet.

What Unclenick is saying is that you can expect that to happen when using a relatively slow-burning powder in a relatively short barrel. Sometimes it is "worth it" to get the maximum velocity out of your gun. But, it tends to create a LOT of variation in the actual muzzle velocity of your bullets from round to round. And, in an auto-loader, it can make a mess of the inside of your action and lead to reliability problems until you strip it and clean it out.

So, normally folks choose a powder that will burn completely or nearly completely in the length of barrel that they have. Sometimes that is hard to do with a short-barrelled gun that uses a cartridge that has a large case and a low pressure rating (such as the .38 Special) without loosing a significant amount of muzzle velocity. (Not exactly sure what cartridge you are shooting.)

Anyway, you do not want to reduce your N350 load below the "start" value in the data you are using. That will not get more of the powder to burn; it will make even less of whatever you use succeed in burning, because the pressure will be even lower, and powder burns slower at lower pressure.

If you can increase the charge weight and still stay below "max" in your data, then try that and see how much better it gets the N350 to burn. Of course, don't exceed max. And, don't keep going towards max if you start getting pressure signs. The pressure data accounts for the way the powder burns in your cartridge, so it is not safe to assume that you are getting lower peak pressure than the data indicates just because you are seeing unburned powder. The peak pressures are probably the same no matter how short your barrel is, because the peak is normally reached before the bullet has moved more than an inch or so.

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Old August 30, 2012, 08:59 AM   #6
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The barrel length does not have a lot do to with powder burnup.
Too slow a powder will leave unburnt granules behind in an 8" barrel... or a 28" barrel. I get unburnt IMR 4227 in my 6.5" .44 magnum, but the load shoots very accurately.

I doubt you will get a nice clean burn of N350 at .38 Special chamber pressures, even at the maximum. It is more suited to heavy bullet 9mm, .38 Super, or low end .357 Magnum.

I realize you are trying to do it all with one powder because of high component prices and that is just one of the results of such a compromise.
If you get decent accuracy, don't worry about it. Just point the barrel straight up when you eject the empty cases so as to not get unburnt powder granules under the revolver's extractor.
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Old August 30, 2012, 09:56 AM   #7
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Jim is correct in principle, because adequate peak pressure is what actually determines whether or not the stuff burns up. That's why powders that produce high velocities, like H110/296, only work out well in higher pressure chamberings and don't make good reduced load powders. However, I'll ague that snubbies are a special problem in that some loads that seem to work fine in 3" or 4" guns suddenly grow a lot of ME ES when moved to a 1 7/8" snubby barrel.

My surmise has been that these problem loads experience uneven ignition delays in any revolver, regardless of barrel length, due to primers unseating the bullets to an irregular degree before the powder really gets burning, and that in that circumstance the bullet base location in the barrel at the moment the peak pressure is reached has a ┬▒tolerance that, with slower igniting powders, includes a point about 2" down the tube. I may be off base with this and some other explanation may account for the phenomenon. Regardless of the actual cause, though, going to a faster powder cleans it up a good bit.


James:

ES: Extreme Spread

MV: Muzzle Velocity

SD: Standard Deviation

VMD: Volume Measure Density (a misnomer by itself as the units are actually the inverse of density; cc/grain or cc/gram), but more properly called VMD Factor, which clears up the unit issue, as you multiply a desired charge weight by it to get the number of cc's you would need to meter that weight if the VMD were accurate. Because the exact VMD Factor varies with each lot of powder produced, Lee instructions say the result of the calculation is an estimate.

Bulk Density: How much weight the powder has per unit volume. Since you would measure a known volume then weigh it to determine this number, it obviously includes the volume of the air spaces between the grains. If, for example, you tried to measure the density as specific gravity based on water displacement, the air spaces would fill with water an not be counted. The result you would then get is called Solid Density because that air space is removed, same as it would be if you had squeezed out all the air and pressed the powder into a solid lump.
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Old August 30, 2012, 12:35 PM   #8
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Wow!! This is like being back in physics class!! thanks for the mini reloading glossary!!

If there is one constant with reloading it is that once you learn one thing, it reveals another 10 mysteries to be resolved!!

Well, I may try and go up to another charge to see if there is any great change. First, though, I may also drop the crimp from a half FCD turn to a quarter: Accuracy is not great, I must say.

I was really surprised by how accurate my little snub was with factory wadcutters. However, my reloads were less consistent. It could be my technique. So far I've shot this gun least, but given the results I've had before I think it is the ammo.

Also, being only 125gr bullet,the seating depth is quite small. Perhaps this is also has implications for accuracy?

PS cases are S&B. Mostly my own but also some scavenged from the range bucket!! I have no shame!!
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Old August 30, 2012, 03:47 PM   #9
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Quote:
My surmise has been that these problem loads experience uneven ignition delays in any revolver, regardless of barrel length, due to primers unseating the bullets to an irregular degree before the powder really gets burning, and that in that circumstance the bullet base location in the barrel at the moment the peak pressure is reached has a ┬▒tolerance that, with slower igniting powders, includes a point about 2" down the tube.
I assumed the same, when I encountered the issues with Lil' Gun.
Because... I wasn't getting "fused powder" with light charges, but heavy charges.
I was working up a handload for .22 WMR, from something like 3.5 gr to 7.5 gr. From the starting charge to about 5.5 gr, it worked well, but had low muzzle velocity. But, once I increased the charge to anything greater than that, erratic burns became the norm and I stuck quite a few bullets in the bore (anywhere from 1/2" to 2" from the case mouth).

Based on the evidence I had available at the time, I decided it all came down to one basic factor:
Primers unseating the bullets and starting them in the throat/bore, causing the powder to 'fizzle' with the loss of pressure after ignition. This also resulted in the loss of chamber seal, if the bullet fully entered the bore.

The more powder I had in the case, the farther the bullet would be pushed into the bore by the primer. And... the farther the bullet got pushed, the greater the sudden loss of pressure was, resulting in the 'fizzle'.
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Old August 31, 2012, 10:17 AM   #10
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FrankenMauser,

Interesting about the quantities involved. I'd have expected more successful start pressure for the same reason that full loads of H110/296 work, but light loads can fizzle and leave a bullet stuck in the bore. But then, that's an old formula spherical powder and hard to light, relatively. Lil gun is newer and a lot of the newer sphericals have more advanced deterrent coatings that don't cause the ignition issues the older ones did. May account for the difference in behavior you saw.


James,

Commercial wadcutters, being loaded flush with the case mouth, don't leave a lot of room in the case for powder. As a result, expansion as a multiple of the unfired powder space is rapid once the bullet starts moving, and in order to make gas fast enough to keep up with that and not be large enough to burst the small powder space, they use small quantities of very fast powders. So it's an example you already have of a small quantity of fast powder verses a larger quantity of slow powder in that same gun. Pretty much proves that it's going to be better when you switch. Here we use about 2.7 grains of Bullseye or 3.0 grains of 231 in most .38 Special full wadcutter loads seated flush with the case mouth. This is right in the range of pressure and burn rate of N320.
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Old September 1, 2012, 01:42 PM   #11
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I just got jumped over in another forum for even suggesting using faster powders in these short barrels due to unburnt powder. You get faster velocities out of the slow powders, but the efficiency is way down. Basically you waste several grains per round of powder that just gets blown out the barrel, when a faster powder burns cleaner and more completely.I do prefer slower powders, but only to the extent of where they burn clean and gives the performance I want.
N320,N330,Hp-38 or AA#5 are some that run that fine line quite nicely. I have used 3N37, N350, and even 3N38(impressive fireball) with good results in some high pressure wildcat calibers.
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Old September 1, 2012, 02:13 PM   #12
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"The barrel length does not have a lot do to with powder burnup."

Yes...

And no.

One needs to factor in the pressure at which a particular cartridge is designed to work at.

A short-barreled .357 Magnum loaded with 296 will leave behind a lot more unburned powder than one with a longer barrel. The longer barrel allows for a longer dwell of higher pressure, giving a better overall burn, whereas with the short barrel the pressure drops off much faster, leading to more unburned powder.

In a .38 Special, though, a slow burning powder may well never reach an optimal peak burning pressure, and so will tend to be a lot dirtier and a lot more wasteful of powder no matter what barrel length you use.
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Old September 4, 2012, 01:53 AM   #13
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Unclenick: Help me if you can. I have several cans of vv318. I want to use them in any pistol. I called the dist. and they told me it was never imported to the states.

The only data I found was for shotgun.

The burn rate seems to be similar to 320.

Some day it will probably be tried in 38.
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Old September 4, 2012, 06:00 PM   #14
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I find N312 and N318 between N310 and N320 in some burn rate charts. But both are absent from Vihtavuori's own current burn rate chart. Neither are they mentioned in my 1995 Vihtavuori Oy hardbound manual, so I suspect they are obsolete and discontinued and have been so for some time. I still find the Scot Brigadier rifle powders in some burn rate charts, too, even though their plant burned down in the 90's and was never rebuilt. Good powders, but long gone. On the Internet, information never dies completely.

Anyway, age alone is a good reason to establish loads for N318 and use it up. Powder gradually deteriorates with age and some deteriorate a lot faster than others. You'll want to be careful when you open these to look for red dust and acrid odor, just to be sure they haven't already gone too far.

I would start by writing Vihtavuori. They are part of Lapua, now, and the address would be info@lapua.com. They may have old data available. If you send them any lot numbers you have, they may also be able to tell you how old the powders is.

If you can't get any information that way and the powder looks good, I would take a magnum revolver and load target loads using N310 data as a starting point. If you have any N310, a chronograph would be useful to help make a comparison. If the N310 shoots bullets faster, you can almost certainly bring these slightly slower powders up to the maximum velocity that N310 produces in your particular gun with that same particular bullet.

Beyond that, you just have to follow the usual load workup practice of watching for pressure signs.
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Old September 4, 2012, 11:42 PM   #15
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Unclenick: I do have a Chronograph. I was going to do just what you suggested working a load up in a Magnum Revolver.

I had a small store when VV was first imported and this was the powder that came when I bought the first order. I didn't have a choice, I had to buy a mixed lot the local dist. put together.

I have used much of the powder line successfully. My customers would not pay the extra price for VV. So, I have been loaded and shooting it for years. I still have the paper reloading guide and the hard back book you spoke of.

Thanks for the come back.
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