Barrel length, roundball size, etc. and range

[bluelake]

I have been researching a kind of smoothbore matchlock musket they used here in Korea called a cheonbochong ("thousand pace gun").  There are almost no examples left today.  It was a kind of wallgun and, according to historical records, a main interest for the designers was to get as much range with it as possible.  One of the criteria for being classed as a cheonbochong was that the musket is at least four inches longer than a standard Korean matchlock (which would have been about 47 inches).  I could find no mention of what the bore diameter should be.  In any case, one recorded example was 65" long and weighed about 22 pounds (no listed bore diameter); another was 78" and .90 cal. At the Korean Army Museum (on the campus of the Korea Military Academy) there is a long matchlock that fits the Korean length criterion for being a cheonbochong, as it is about 53" overall length and .59 cal. I've seen--and even held--that one many times. Next week, I plan to visit a university museum here in Korea that has a cheonbochong, although quite a light one: 54.5" overall length (barrel length 41"), .59 cal. and less than 8 pounds weight.

My question is one of caliber and barrel length related to maximum range (not necessarily effective range) of a smoothbore musket.  I'm familiar with the limitations of a long barrel. In the case of black powder musket shooting, the longer barrel on a smoothbore gives a chance for relatively larger amounts of powder to burn; whereas, in the case of a relatively short barrel, if one were to put a large amount of powder in it, much of it would be unburned and wasted. However, with rifling, long barrels (and excess powder) aren't needed quite as much; take for instance the comparison between the Remington rolling block .50-45 cal. carbine and the .45 cal. Korean matchlock--140 years ago this Saturday, Koreans and Americans were pitted against each other and the RRB had no problems with the 150m distance between the American and Korean troops by the main fortress. On the other hand, the Korean matchlocks, according to US records, were more a nuisance than anything else when their spent roundballs hit the hill the Americans were on.

The Japanese also had long matchlocks with relatively small bores (about .59 cal.) and called them "loophole guns", which seem similar to what still exist here in Korea.  However, there don't seem to be records as to their maximum range.  So, taking into account the largest and smallest caliber cheonbochong left in Korea, if you wanted to get the most range out of one with a 60" barrel, what caliber would you choose?  .59 or .90 or something else?  How much of a charge?  (Reading the old wallgun thread, some of you went up to 300-400gr)  It seems to me that one would want the mass of a larger roundball...

[Stormrider51]

Let me see if I can stumble through a thought or two.  Range is all about velocity when the projectiles are ballistically equivalent as they are when both are round balls.  If a .59 and a .90 round ball are dropped at the same instant they will hit the ground at the same time.  If they are fired on the same trajectory at the same speed they will likewise hit the ground at the same time.  What changes the equation is velocity.  A faster ball will fly further in the same amount of time as the slower ball.  So even though they hit the ground at the same time the faster ball wins the distance contest.  Then there are the "human factors".  How much recoil will the shooter be subjected to?  I don't know about you but I can handle launching a faster .59 than I can a .90 if I'm having to ride out the full recoil of both.  But the weight of the gun comes into play as well.  A really heavyweight .90 might have less recoil than a relatively lightweight .59 even if the .90 fired a heavier charge.  Just to keep things interesting, let's consider terminal effectiveness in deciding which is "better".  A .90 ball is going to carry more momentum at extreme range and should therefore penetrate better.

So I guess that if I'm standing on a parapet of a city wall defense and can lay my 22 pound gun on the wall for support and if the prime consideration is to launch the most effective ball the longest distance...I'd have that .90 loaded with however much powder would burn effectively in the very long barrel.  Guns in that situation were more like artillery raining down death on the enemy.  The amount of elevation or tilt required for maximum distance would have you shooting blind anyway.

John

[bluelake]

Let's ramp the scale up a bit to illustrate the point.  Which has further range, a smoothbore .58 cal. musket with a 44" barrel or a smoothbore Dahlgren 12-pdr boat howitzer with a 44" barrel?  How about a smoothbore 9" Dahlgren?

[Stormrider51]

It would still come down to which one fired the fastest projectile if all we are worried about is distance.
 
John

[bluelake]

That is what my questions were about--range.  A .58 cal. musket might use 65gr. of bp and have a velocity of 950fps.  Even with rifling, its range was about 600 yards.  A smoothbore 12-pdr. howitzer used a 1-pound charge and had a velocity of 1,054fps and had a range of 1,085 yards.

[huntinguy]

seems like the other part of the equation.  is how much pressure the barrel at the breech can handle. From what I have seen, the larger bore gets more velocity out of lower pressure (to a point).

You might want to ask at the museum if they have done an examination to discover the type of metal (the elemental components) and structure. This could give a better idea of what pressure, hence, velocity the barrels could stand.

I did have some information on flintlock wall guns but... I don't know where it went. I would think they would out range the matchlock.

[bluelake]

Since this is just hypothetical, with all else being equal, which would perform better for maximum range, a relatively large or relatively small roundball?  In other words, in this same hypothetical situation, you were challenged to a contest to see whose roundball could go the farthest, and you had two 60"-barreled "wallguns"; one was a .58 cal. and the other was a .90 cal.--which would you choose?

[biliff]

To paraphrase Napoleon, God is on the side of the bigger balls.

Your 150 m. comparison with the American carbines brings up the question of how were the matchlocks loaded? If it was a loose bare ball over powder, then yes they wouldn't have been more than a nuisance at that distance. Loss of velocity and lack of accurracy would have been a problem. Given a decent ball to bore fit using wadding or patches and things would have been a bit more dangerous assuming the troops were reasonably well trained.

For longer range shooting the bigger ball has the advantage. While not quite the same thing as you're describing, my .32 isn't worth spit at distance. If I crank it up I can shoot 100 yards with a reasonable degree of accuracy, but not much oomph. 200 yds, forget it, I can't crank it up enough to do any good.  My .58 on the other hand will not only carry easily to 200 yds but still carries enough velocity to kill.

If I want to do some damage at range with a roundball and BP I'll take the bigger ball every time.

[bluelake]

Thanks, Biliff.

The Korean method of loading was powder/ball/paper wad.

[Gambia]

Okay, I choose the .90 over the .58 for getting the most distance.  If recoil is not a factor, then the larger caliber ball has more area in which the burning powder has to push on, resulting in lower pressure but also being able to utilize more powder.  The larger diameter barrel can burn more powder and get the RB going faster before leaving the barrel and the heavier weight of the .90 is going to be able to stay in a straight line longer before is starts to be deflect off it's original path.  It will reach a higher arc in it's flight time and be able to cover more ground before landing back on earth.  Now if a spin is imparted to both via rifling then I think the distance of both will increase.  Smoothbores are limited in range because with no spin on the bullet they are shooting, be it a RB or lead conical they both start to wobble in flight, exposing more surface to wind resistance and loosing velocity.

 Now, if all conditions are the same, pitting both calibers against each other and using the same amount of powder from identical barrels then whichever has the most velocity will have gone the farthest.

At least that's the way I see it.  If there are flaws in my thinking I'd appreciate some enlightenment most sincerely.

[bluelake]

Thanks, Bull!

[huntinguy]

Thanks, Biliff.

The Korean method of loading was powder/ball/paper wad.

so,  there was nothing to seal the expanding gas?  Did they fit the ball tight, have to hammer it down? Were these things rifled?

I would think range would suffer exceedingly, gas blow by, ball rattling down the barrel.

Bet you could have a tea party at 300 yards and not have to worry about chipping the china.

[bluelake]

Exactly how tight the fit was, it is hard to say.  I have recovered matchlock musketballs (which were about .45 cal.) from the side of a hill where the battle between Korean and US forces took place in 1871, and I have measured the bores of several old Korean matchlock barrels, which were about .45 cal., but I never got to do them at the same time (and I didn't have calipers when I measured the bores).  For the Korean long matchlocks (cheonbochong), I am not aware of any extant roundballs for any particular musket to check fit.  All Korean matchlocks were smoothbore.  

I have loaded my repro Korean matchlock in the traditional way and it shot quite well; I also shot it with patched roundball and the results were similar.

[huntinguy]

I wonder... On the recovered balls, have you measured them with a micrometer to see if they are round or have flats? (I guess you would need an odd flute micrometer for that). You might get an idea of how tight a fit and the deformation from the ball impacting the earth. Considering how long they have lain in the dirt... It is dubious that it would be of value, but you never know. If you could measure enough of them you might get a statistical average and be able to work with that number.

"I have loaded my repro Korean matchlock in the traditional way and it shot quite well; I also shot it with patched roundball and the results were similar."

 

Interesting..... I would not have thought that... I may have to rethink some of my research material....

[bluelake]

I wonder... On the recovered balls, have you measured them with a micrometer to see if they are round or have flats? (I guess you would need an odd flute micrometer for that). You might get an idea of how tight a fit and the deformation from the ball impacting the earth. Considering how long they have lain in the dirt... It is dubious that it would be of value, but you never know. If you could measure enough of them you might get a statistical average and be able to work with that number.

They were not deformed very much and one was even in fairly pristine condition.  I think a lot of it was due to their losing velocity by the time they impacted the hill.  I mic'd them in different directions and the diameters did not vary a lot.  By their weight, they also gave a very close approximation to what a .45 cal. lead roundball would weigh.