Flint vs percussion power comparison

[M. De Land]

I read somewhere that given equal caliber and powder charge, flintlocks are inherently less powerful than percussion guns due to pressure loss through the vent. On the surface, it seemed to make sense but I was curious about what the actual difference might be. I don't have a chronograph, so I set up a simple penetration test.

• .54 percussion Hawken
• .54 flint Hawken
• Two sections of green poplar log
• Both rifles were loaded exactly the same with 125 grs. FF.
• Log sections were set up at 40 yards with end grain facing
• When the smoke cleared the log sections were split and the ball channels compared.

As shown in the photo below, both balls traveled approximately the same distance. Under hunting circumstances I suspect the game would not notice any difference between the two rifles.

Flintlock on the left / Percussion on the right
View attachment 2532

Very neat test and thank you for both doing all the work and sharing your results. Your test has inspired me to replicate your experiment with my two match Yazel hand guns, both .36.cal in flint and percussion. As in your test they are identical except for ignition and I do have a chronograph.
I think a better comparison would be if we were to use the same gun reconfigured to shoot both percussion and flint as no two barrels are precisely the same in bore diameter, bore smoothness ,rifling etc.
The other thing is wood density change from one part of the log to another.
I encounter significant wood density difference in the same stock when checkering .
Your test did seem to generally correlate well to what we know and that being all things relative and equal, the less gas escapement from a percussion gun will cause it to burn the same amount of the same brand and lot of powder more efficiently and produce more velocity.
A test I would like to conduct and don't have the means at hand to do is the different in velocity between a coned vent liner and and none coned vent liner in the same gun.
I'm quite certain the interior coned vent velocity loss is greater but have no idea of how much.
The chronograph, will tell the story very accurately. I just happen to have a Ohler P-35.

 

[M. De Land]

Very neat test and thank you for both doing all the work and sharing your results. Your test has inspired me to replicate your experiment with my two match Yazel hand guns, both .36.cal in flint and percussion. As in your test they are identical except for ignition and I do have a chronograph.
I think a better comparison would be if we were to use the same gun reconfigured to shoot both percussion and flint as no two barrels are precisely the same in bore diameter, bore smoothness ,rifling etc.
The other thing is wood density change from one part of the log to another.
I encounter significant wood density difference in the same stock when checkering .
Your test did seem to generally correlate well to what we know and that being all things relative and equal, the less gas escapement from a percussion gun will cause it to burn the same amount of the same brand and lot of powder more efficiently and produce more velocity.
A test I would like to conduct and don't have the means at hand to do is the different in velocity between a coned vent liner and and none coned vent liner in the same gun.
I'm quite certain the interior coned vent velocity loss is greater but have no idea of how much.
The chronograph, will tell the story very accurately. I just happen to have a Ohler P-35.

 

[Col. Batguano]

There are so many variables that need to be accounted for, but the traditional wisdom is that you need to increase your powder charge by about 10% in a flinter to equate to that of a capper. With the load you are shooting, you are in excess of the Davenport maximum powder burning efficiency for both barrel lengths;
32"= 84 gr.
38" = 100 gr.

So, while this is an interesting and practical test, we really need to see the numbers to draw conclusions. One thing is virtually certain though--the cap gun will have significantly less barrel dwell time from seat trip to ball exit, regardless of the exit velocity.