Velocity vs barrel length, a test by the Rice boys

[Dale Halterman]

At Dixon's on Saturday morning, I attended a seminar by one of the Rice boys in which he presented the results of some testing he had done. I just got home last night and can't find the handout with the data, but I will summarize.

He started with a 44" barrel and chronographed a 4 shot string. Then he went back into the shop and cut two inches off the barrel and shot four more. Same charge, ball size, etc:

Continued to 30".

The result was a decrease in velocity at each step, except for some anomalous numbers at (I think) 36".

I asked for permission to post the results here and he said OK, so I will when I find them. He also stated that he would put the results up on their website.

Dale H

[Mike R]

I'd be intersted in the data.  The old Lyman muzzleloading manual showed similar results--if you compare the tested loads for different barrel lengths, in most cases the longer barrels had higher velocities for the same loads.  You have to compare apples with apples. 

[northmn]

Would be interesting.  Mostly if one looks at published data one sees that trend.

DP

[Curtis]

I'd love to see those results!  I am trying to decide what barrel length to go with on my Hawken and they could be most helpful....

[hanshi]

Examination of this data would be very useful as well as interesting.  I've read of similar experiments done with smokeless powder cartridge barrels.  I am lead to believe that black powder gains more advantage in longer barrels compared with smokeless.  Smokeless appears to be consumed in a much shorter length of barrel and often short barrels will outperform longer ones.  I don't think the often given example of .22LR maxing out in an 18" barrel is relevant; bp burns at a steady rate unlike smokeless which varies according to the pressure it builds.  Win. 296, for instance, will squib unless loaded max with full pressure; bp won't do this. 

[Dale Halterman]

OK, sports fans, here it is.

First, he started with a 44" barrel, 50 caliber, 1:66 twist, .490 ball, .015 pillow ticking patch lubed with bore butter. He used a percussion lock and CCI #11 mag caps. Powder charge was 80 grs 2F Goex, and the chronograph was set up 15' from the muzzle.

Results or four shots at each barrel length from 44" to 30" in 2" increments:

length                  average velocity, fps                          extreme spread, fps

44                              1601                                                 42

42                              1583                                                 28

40                              1573                                                 21

38                              1555                                                    5

36                              1512                                                  12

34                              1531                                                  50

32                              1501                                                  23

30                              1471                                                    6

Note that the velocity for the 36" length appears to be low, compared to 38" and 34".

Dale H

[Ben I. Voss]

Quick! Grab another barrel and do it again! We want to see if it does the same thing this time!!

[roundball]

Results or four shots at each barrel length from 44" to 30" in 2" increments:

Very interesting...not as big of a difference as I would have guessed.

Just extrapolating from this single test, potentially the velocity difference between my former 32" .58cal barrel and my new 38" barrel might only be around 50 fps faster.

Thanks for sharing that...

[Dphariss]

Interesting.
At last chrono test my 38" barreled 54 flint with 90 gr of FFFG swiss made 1900+.
My 16 bore (one ounce ball) with a 30" with the breech makes 1600 with 140 gr of FFG Swiss.
I wish they had used both FFFG and FFG.
FFG is very inefficient, grains of powder per velocity gained, with the round ball unless the bore is fairly large, like 58 or larger.

Dan

[Mike R]

Interesting.
At last chrono test my 38" barreled 54 flint with 90 gr of FFFG swiss made 1900+.
My 16 bore (one ounce ball) with a 30" with the breech makes 1600 with 140 gr of FFG Swiss.
I wish they had used both FFFG and FFG.
FFG is very inefficient, grains of powder per velocity gained, with the round ball unless the bore is fairly large, like 58 or larger.

Dan

Go to the Lyman book, they used fffg and different barrel lengths for a number of calibers up to at least .58.

[Scott Bumpus]

Interesting that the 38" gave the least velocity spread,  this might prove to be the most accurate length for that combination.