Title: Ammonpulver Part Six: Finding the burn rate of an unknown powder, observations

Retrieved: 12/12/2014
Last Post: 09/20/2004

Observations: I left my Mosin-Nagant for a whole a week before cleaning the barrel to check for corrosion and found none, indicating that ammonpulver burns clean with no corrosive residue when properly boosted?

Just like other propellants, ammonpulver can't have any contamination from any flammable liquid, oil, grease, wax, Vaseline, alcohol, tar, solvent, paint thinner, preservative, etc. mixed in with it. It has to be just plain ammonium nitrate and plain dead-burnt charcoal. Dead burnt means that it is black, odorless or nearly so, and there is no wood residue like creosote left in it (which you can smell).

The booster charge for ammonpulver MUST NOT be a double base propellant! Only single base propellants like the IMR series are reliable. I tried IMR4895 in place of the IMR4198, H4198, and XMR2015, which gave virtually identical results. Double base propellant boosters in contact with the ammonpulver have the potential to interact over time and the burn rate may be affected. This has not been proven, though.

The exponential ratio of the ammonpulver to booster is determined by first finding the minimum amount of booster powder that will reliably initiate a set weight of ammonpulver in conjunction with a specific projectile weight. For instance, in the .308 Winchester a 23-grain ammonpulver charge needs a 6 grain booster of IMR4198 for a 180-grain bullet.

The common logarithm of 25 divided by the common logarithm of 6 is 1.75 (actually 1.7499 but 1.75 is fine), so that means that for ANY .308 Win ammonpulver load for a 180 grain bullet, the IMR4198 booster charge raised to the 1.75 power (1.75 = 7/4) is the weight of the ammonpulver charge it will boost, or the same calculation working from the other way is the ammonpulver charge needs a booster that is its 1.75 root. The 1.75 root is the same as to the 0.5714 power, 1.75 = 7/4,0.5714= 4/7.

A calculator that has keys labeled "LOG" and "Y" with a little x after it up on top is used to calculate the logarithm/exponential values. Unfortunately there is no other easy way to calculate these values except using a scientific calculator or a scientific calculatoremulator program foryour computer . You can download free scientific calculator programs off the Internet so you can do these calculations using your computer with a little instruction.

Linstrum
09/19/2004

More observations:

The exponential or logarithmic relationship between the main charge and its booster has applications outside of ammonpulver loads. The over-all behavior of ammonpulver is a lot like WC860 and WC872 that need boosters as well to burn completely without residue in small volume cartridges. Those slow .50 BMG and 20 mm powders work best with a captive booster of some sort over the flash hole, and when those surplus propellants first appeared Felix and some of the other original Cast Boolit folks found that boosting them would promote 100% combustion using somewhere around three, four, or five grains of the faster extruded "stick" single base propellants like IMR4198 and IMR3031. The amounts of booster for the various calibers, loads, and projectile weights were never explored very much beyond the initial discovery that a small amount of them would clean up the combustion of the slow military big bore powders. It wasn't investigated because there was no need to as they were effective and very safe in a few grain quantities, however with the data I got from working with ammonpulver it is pretty clear that there are specific booster to main charge ratios for them as well.

Felix and the others also gave a pretty clear warning to keep away from experimenting with anything more than a few grains of booster, or creating duplex loads of the commercially manufactured smokeless and/or black powder class of propellants, because of the potential for the propellants to mix together. Mixing has been very well proven time after time to be extremely disastrous when certain kinds of incompatible propellants are mixed. In boosted and duplex loads the components are never allowed to mix and provisions to keep them from mixing have to be made. Usually load compression is sufficient and in my ammonpulver loads the mixing is prevented by the ammonpulver, which is like powdered sugar and immobilizes things without being compacted to any great degree, unless shaken hard.

Linstrum
09/20/2004

Hey, Joe! Your observations about 5010 "Purina Rifle Chow" are right on with what all the others here found out about it who pooled their information to figure out how to use it. It is a little different from the double base WC860 and WC872 ball powders and I have never needed to use a booster with it either, because it has always burned clean for me except for one puzzling instance. I have also been reluctant to use a booster with it because the "log"-sized grains will allow the booster charge to sift into it and mix unless a diaphragm made out of a paper disc is used between the booster and main charge to keep them apart. One of the things the stuff likes is what you already found out, which is a full case, or a large case capacity with a small bore diameter, which is another way of describing what a magnum is. It seems to me that it works pretty good in the 6.5x55 Swede Mauser, which is pretty darn close to the .260 in shape and size. Of course it works great in the classic magnums like the Winmags and Weatherbys, etc. The puzzling instance when I had trouble with the Purina Rifle Chow was in a .50 BMG where it is normally used. I had what I thought was a dud primer but when I opened the bolt and ejected the cartridge the boolit was jammed in the throat and the powder spilled out of the case. I found a long branched stack of powder grains all melted together that stunk pretty strong exactly like a railroad tie on a hot day. The stack went the whole length of the cartridge from the flash hole to the shoulder-neck junction and showed the path of the primer flash through the powder. Out of curiosity I reprimed the case and put what what was left of the old powder back in with the same boolit and it fired just fine.

Somebody here has probably already used a booster with 5010 and might have some good info for both of us. If you ever do use a booster with 5010, probably 5 grains or less will be good enough and IMR4895 would be my choice. Start out low and work up until it is clean burning. Also, remember to add the weight of the booster to the other powder to get the weight of the entire powder charge.