Testing black powder (other than golf balls)

[Fulmen]

If I'm to make BP for sporting i would like a good method for testing it. Golf balls are fine, but this test is designed to simulate pyrotechnic use and require manual measuring. I would like something more accurate and relevant for sporting use. The best idea I can come up with is a strain gauge mounted on a single shot mechanism as I happen to have one such unit (RSI pressure trace). Ideally one would measure both pressure and velocity, but for simplicity I think pressure alone will be enough. So a I'm thinking a short chamber with a constriction to build up pressure. Any other good ideas or input on this method?

[NeighborJ]

I'm sorry but I doubt you will obtain any form of usable results without an element of time (velocity). Even a very slow powder has potential to produce the exact same pressure as even the fastest powder. In powder testing it all comes down to how fast or slow a given amount of propellant can achieve complete combustion. And with bp firearms, it is not advisable to use the fastest powder possible. If a fast bp can achieve complete combustion before the bullet has begun to move it can blow up in your face. And likewise if the bp does not achieve complete combustion before the bullet leaves the barrel, that energy will be lost. The goal in firearms is to provide a perfect burn speed to PUSH the bullet down the entire length of the barrel.

This is why baseball and golfball testing is so widely accepted as the most effective method for testing bp.

Edited August 13, 2016 by NeighborJ

[Fulmen]

I sincerely doubt that golf ball tests are anywhere near "the most effective test". It might be the most useful when one considers the simplicity and lack of investment, but that's not the same.

[NeighborJ]

Even a bomb calorie tester will only test the energies available for use but it needs the element of time of reaction in order to get a value of its effectiveness as a propellant.

I understand the golfball test is not perfect but anything short of firing a gun will not allow for accurate results. Time is essential for the test to yield fruitful data. Even stopwatch timing spolettes is flawed due to the variations of density in different bp.

[Fulmen]

The strain gauge logs the total pressure curve (https://www.shootingsoftware.com/pressure.htm), and for a non-closed bomb the peak pressure will depend on the burn rate (among other things).

 

I might construct the gun so that I can be loaded with a bullet if needed, this will allow me to test real performance as well.

[DavidF]

Mike Swisher has often mentioned the use of a small reloaders scale and an eprouvette. IIRC, it is specifically used to test black powders for use in guns.

[NeighborJ]

OK I can see what you are doing now, the graph plots out a measure of pressure over time and not just peak pressure. This will be more accurate then golf balls for sure. I wonder if firearm manufacturers can provide a performance chart you can use to make sure those specs are not exceeded?

[patsroom]

Here you go. For about $185 dollars you could buy on of these brand new........Pat

Edited August 13, 2016 by patsroom

[NeighborJ]

Just what is that?

[patsroom]

Just what is that?

It is a Black Powder Tester that is for sale on-line. It has a spring in the wheel to help in measuring the power of fired powder. I think it can test about 10 grains of powder at a time. But if one wants a cheaper tester there is BLACK-POWDER TESTER, By Ned Gorski that he made and has a PDF out on it, which can be found on the internet. It deals with testing by ejecting a dart like devise.............Pat

 

 

[memo]

that is pretty cool, it will do what op wants for sure. sometimes old is good.

 

memo

[patsroom]

^{It is the old way that they used to test black powder, they had a few different devices all petty much on the same ideal. These are brand new and ready to use, but I find the price to high for my taste. I do think a smart person could design one to do the same thing if they thought about it (and if the do please post on how to make one).......Pat}

[Fulmen]

Wow, there are a lot of clever solutions out there. But so far none that measure actual pressure like I plan to.