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Black Powder Efficiency?

 
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Bigfoot
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Joined: 21 Dec 2009
Posts: 77
Location: Upstate New York
Real Name: Jonathan Steffan

PostPosted: Fri Jun 03, 2011 3:36 pm    Post subject: Black Powder Efficiency? Reply with quote

I have read that black powder is inefficient, and that heavier loads do not produce higher velocities. Diminishing returns, and all of that.

I just was at the range with my .50 Early Virginia fliinter. I shot groups over a chronograph at 65 and 100 yards. I started at 50 grains with a PRB and went up to 100 grains. In each case, the ratio of powder to velocity was consistent. Each 10 grain increase in powder charge produced an equivalent increase in velocity. Straight line graph.

I stopped at 100 grains because I could see no need for over 2100 fps and 1700 ft/lbs of energy. Groups at 65 yards with all charges were all 1-2" groups of tens and x's, and at 100 yards they were all 3" groups, with more horizontal that vertical stringing (my eyes and the breeze.)

It seems that the data I gathered today disagrees with conventional widson on the subject. What has your experience been?
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Loyalist Dave
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Joined: 21 Aug 2008
Posts: 294

Real Name: David Woolsey

PostPosted: Sun Jun 05, 2011 8:46 am    Post subject: Reply with quote

Lots of variables. 2Fg 3Fg etc. Length of the barrel. However, what I think they are referring to is the inconsistency, and the drop off of increase. For example, one site shows with a 32" Hawken, using 2Fg, a 60 grain load chronographed at 1434 fps, a 70 grain load at 1643 fps, an 80 grain load at 1838 fps, so roughly a little more or just about 200 fps for each ten grain increase..., But the 90 grain load was at 1950 fps so the increase was 112 fps, and when upped to 100 grains the MV was 2052 giving an increase of 102 fps, and the 110 grain load gave a MV of 2135 so only an 83 fps increase. So from 70 to 80 with ten grains they got 195 fps, but from 90 to 100 with only 112 fps increase. If it was consistent they should've had a jump up to around 2030. So the MV did increase, but the rate dropped off.

Now with a longer barrel and a different caliber and different granulations, your results will vary.

http://www.epmuzzleloaders.com/ballistics.html

LD

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Bigfoot
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Joined: 21 Dec 2009
Posts: 77
Location: Upstate New York
Real Name: Jonathan Steffan

PostPosted: Sun Jun 05, 2011 11:28 am    Post subject: Black Powder Efficiency Reply with quote

Having read all the usual sources, and hearing all the conventional wisdom, I was surprised at my results.

42" barrelled flintlock, .50 caliber, .490 patched RB, 3F Goex, from 50 to 100 grains increase, there was no plateau of the increase. No diminishing returns. Just a stright line graph. Groups remained pretty consistent, too.

I did not go beyond the 100 grain load, so it is possible that the expected decline in increase of velocity may have occured after 110, 120, etc. Far more powder than I am going to put in my cutom TVM Lefty Flinter for the sake of science!!!!

I would like to see someone else replicate this test in their gun to see if perhaps this is another example of "conventional wisdom" being equivalent to "wives tales."

I will repeat this test my self with another rifle in the near future.
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Loyalist Dave
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Real Name: David Woolsey

PostPosted: Mon Jun 06, 2011 5:40 am    Post subject: Reply with quote

Ah but it isn't a wife's tale. The data demonstrates it as true. Your barrel was considerably longer than the one I mentioned and found on the site. They only experienced in the .50 and .54 calibers a drop off beginning at the 80 grain load, while you have an additional 10" of barrel, and are using 3Fg. I submit that the smaller granulation of powder plus the longer acceleration distance gives you an advantage, not to mention the modern powder. =D

LD

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