Why do hot guns jump violently?

[fnkershner]

Bob - I am glad to hear this from you. So this is a fact. Can you also tell us if the jumping gets more pronounced as you continue to fire? At what point do you determine the weapon is too hot and needs to cool? Now rapidly are you firing? Are you reaching the speed of the British Tars? 2 shots every 3 min?

[bobcat]

Hi,

 

One thing that is never  done by todays  black powder cnnoneers is hurrying shots. The Royal Navy records for speed are safe for all time. The loading and firing drill should be adhered to. Slow and steady prevents stupid things from happening.

As for "jumping" guns, my experience has shown that once a gun gets hot it will steady out and the recoil pattern will stay the same. Personally I have never seen a hot gun having to be cooled down, but I beleive the stories of guns getting hot enough after continuious and fast firing to need a little cooling down.

I wonder how much stress a bucket or two of cold sea water would have on a red hot gun.

 

Bob Friedman

[jud]

We were not dealing with cast iron and an unloaded hot gun was not attacked with buckets of seawater, we would have used hoses. Destroying a hot barrel with copious amounts of sea water would only be done to attempt to prevent an explosion in the bore, caused by heat cooking off the explosives in the projectile.  If a projectile could not be removed from a hot gun, the cooking off of the projectile was a real danger. Hot guns and explosive projectiles spending much time in them are dangerous, a propelling charge cooking off was not desired but not as dangerous, it would just clear the bore. I have experienced misfires in hot guns,  was successful in re-cocking the firing pin and lucky enough for the round to fire. I have also attempted to re-cock and attempted  to fire unsuccessfully with warm guns, waited 30 minutes to avoid the possibility that it was not a miss-fire but a hang fire instead, then opened the breach and extracted the round from the chamber, always a nervous time. First time I experienced a miss fire as Mount Captain was on a 3" 50 aboard a Heavy Cruiser, I cleared the mount as instructed but I remained with the gun, the Warrant Gunner came up to the gun and we waited our 30 minuets then I very carefully opened the breach, caught the rear of the case and worked it clear of the loader and handed it to the gunner. Horror of Horrors, he upended that round, thumped the primer with his finger and tossed the round overboard while saying defective primer, "even throwing a live round overboard required that the round hit the water case down, if it hit projectile down and the propellent went off, the case would act as a rocket and come back, case down prevented that". Never needed to hose down a hot gun but was prepared to do so quickly if needed. Closest to a projectile exploding in a bore was in RVN, firing old WW 2 ammo while supporting  PBR's in a firefight. Just firing the right gun of a water cooled twin 40 MM, after about 20 rounds the gun made more of a cough than a bang, recoil was short and the projectile blew up just clear of the bore, the shrapnel dispersed in a half moon shape ahead of the gun, none came back towards us that we knew about. The gun quit working so I shifted to the left gun and resumed firing, that kept the rounds going out and didn't allow the loaders to get rattled. When I had time I investigated and found a split cartridge case and broken extractors in the gun, replace the extractors and that gun was up and working. The smoke that the propellent of that round produced was a rotten smell unlike the norm.

I still do not believe that the guns of old, jumped when fired as designed, I have fired to many guns to believe that. Black powder and smokeless powder do have different burning rates under pressure, but neither stay in the bore of a hot gun long enough to change the characteristics of their burn rates. If a gun starts to appear to jump as it warms up, it is because of outside forces or conditions having an effect on normal recoil. There is a reason why no one has came forward with a scientific explanation of jumping guns, that is because there is none. Trails on field guns will work their way deeper on each firing unless they are re fired from the position reached at the end of recoil, but the practice was to push them back into battery, that recoil and pushing back into battery would disturb the ground, the trails would be deeper and in soft ground the wheels would be worked deeper and deeper into the ground. Aboard ship the jumping would destroy the wooden wheels and tear up the deck as well as pulling the breaching  and its rings out of the bulkhead, carronades would destroy their mounting platforms. Think there is a model of a small boat on this site, with a cannon mounted with a track built into the boat to allow the working of the gun and free recoil, If it was normal for guns to jump, they would not be staying in those tracks.

Kind of a windy post, I will not be insulted or distressed if the Moderators choose to remove it, may do it myself later.

jud

Edited October 28, 2013 by jud

[molasses]

I just came across this thread and I believe that hot guns jumped more than cold ones because of the heat transfer from the gun to the powder. Heated black powder will burn faster than when at normal temperatures, and so will modern smokeless powders, some types more then others. In the past I was very seriously involved in firearms marksmanship with several different firearms including black powder cartridge rifles. I noticed that my points of impact were always higher on the target, and sometimes that the recoil was noticeably heavier, on hot days than on cold days or when I left the ammo on the shooting bench in the sun, heating it. The same effect when applied to muzzle-loading cannon seems quite reasonable to me and the most likely primary cause of heavier recoil from hot guns.

[realworkingsailor]

I think there's only one way to solve this mystery....

 

We'll all have to chip in on a 12 pounder, build a replica of a ship's gun station,  purchase a large quantity of shot and powder, and fire the bejeesus out of the thing until we get a definite answer.

 

 

Or we could just call Mythbusters...

 

Andy

[jud]

Call the Mythbusters! Sounds like a good plan. How does one get that in the pipe?

jud

Edited October 30, 2013 by jud

[fnkershner]

Unfortunately someone got to the Mythbusters before us. There is an episode where they use a 6 lb cannon to test the damage to a dummy from splinters. As a result they concluded that Splinters were not a big hazard on Sailing warships. Now I don't there is anyone on this site that believes that is true. We all know how devastating the splinters could be.

[realworkingsailor]

Yeah.. and if I recall they only used pine wood as a target....

 

Scale that up to some real heavy oak timbers and a 24 pound shot and let's have that discussion again.....

[dafi]

+++breaking news+++

 

Mythbusters busted!!!

 

 

Does one have to say more?

 

DAniel

Edited October 30, 2013 by dafi

[Beef Wellington]

That's fantastic footage you've found there Dafi.

[fnkershner]

Now that's what I am talking about! Thanks Dafi.

[realworkingsailor]

Funny.... Didn't see that gun jump too much though.....

[dafi]

Ok, also no jumping involved, but the last vid triggered Achilles from our german forum to add one more interesting bit to the collection

 

 

Enjoy, Daniel

Edited October 30, 2013 by dafi

[fnkershner]

And they did this over and over twice every 3 min! Amazing!

[rlb]

I've been following this topic with interest.    

 

That last video was cleverly edited.   In the last drill, the scene was cut before the gun fires, and spliced to an exterior shot of a different gun firing.   I have my doubts that this group even fired the gun they were working. (And the breeching rope did look like it was just draped across the barrel of the gun--maybe so it wouldn't get in the way!)

 

Ron

[dafi]

As there was no real charge in the drill, there was no recoil (and no jump of course) and therefor the breeching ropes where not necessarily needed ;-)

 

So I think it was really not fixed for laziness reasons.

 

Daniel

[Beef Wellington]

Was I the only one worried that the sailor loading the charge and the shot was either going to fall out of the gunport or drop the shot?  Would expect the gun to have been brought inboard by at least another couple of feet which would have made all the difference.  Not sure it really accurately reflects the aiming process either, of course quoins would be moved, but the roll of the ship influenced that far more,  the continual lateral training with the handspike because of unequal recoil and a likely moving target was probably much more critical (and harder work).

[LFrankCPA]

Just a few odd comments:

I take offence to the use of the 'sloppy'. In the heat of battle things happen, they did the best they could.

As for the heat radiating outward: I could not begin to tell you the number of times I have 'smoked the stock' of my M14. Most military rifles have some type of protection on the upper barrel so you will not get burned. After a firefight you do not want to grab the barrel. 

Keep in mind that the same force of discharge comming out the barrel of the cannon, came out the lighting hole at the head. Was there in type of protection on the timbers above the cannon for this effect????

Larry

Edited November 24, 2013 by LFrankCPA

[mtaylor]

Jason,

There's reports where the loaders were hanging out the ports and some paintings show this.  The amount of room for recoil is a function of space available as well as the amount of time to get the gun back into battery.  I don't think they would try to train one of the fixed battery guns for a moving target.  A pivot gun maybe.  But that's a lot of weight to try to move.

 

Larry,

 

I agree about doing the best they could.  Everyone does... sometimes fate plays a hand. 

 

Heat is a problem.  Slow fire weapons, maybe not so much but then again, the heat would take a bit to radiate out of one of those barrels.  A machinegun is a different critter as is rapid fire with a M-xx or AK, etc (pick your model). I've had MG barrels glowing red. 

 

The blast out of the touchhole shouldn't have been that bad due to the restrictive size of the hole,  from what I've seen.  Maybe someone who's actually live fired one could weigh in. 

[popeye2sea]

Although I have fired a cannon several times I can not say with certainty how much of a blast would come out of the touch hole.  The powder charges we use are much smaller than a full combat load.  And to be honest, my position on the gun is either worm/loader or sponge/rammer, so I am usually at the muzzle of the gun when it goes off and not really paying any attention to the touch hole.  My impression is that there is a plume of smoke but not much else.  Also much of that plume is from the powder in the pan and touch hole.

[dafi]

If one looks at the film about the carronades in entry #47 at second 0:06, the blast through the vent appears not to be to violent.

 

XXXDAn

Edited November 27, 2013 by dafi

[jud]

First cannon I made and fired was constructed from a 3/4" pipe. Smokless powder from shotgun shells was the propellent. When I finally got the powder burning after many tries, I was very close to the thing, started out behind a log reaching over it. When she went, she spit in my eye, the ball bearing projectile rolled out of the barrel and fell on the ground. Had time to shut the eye so a few small sore spots was all I suffered. Black powder spit a little higher from my home grown artillery but had limited distance, moving gas after being released from containment doesn't go far, regardless of it's peak starting pressure.

jud

[dafi]

Also have a look at this topic: "When the gunz go booooom"

http://modelshipworld.com/index.php?/topic/4503-live-fire-when-the-gunz-go-boooooom/#entry129271

 

Cheers, Daniel

Edited November 27, 2013 by dafi

[LFrankCPA]

I watched the movie Captan and Commander (that does not sound right) the one with Russel Crow. Actually watched it seceral times and commented about how real the ship was. That's were I got the thought about the wick hole....

Larry

[jud]

The ship was real, you can go aboard her at San Diego as well as the Star of India. I remember the Star lying at a dock with the tops down, a sad sight while in the Navy in the early 60's, went aboard her in 78 while still being restored. The term is touch hole or vent, some wick holes are found on oil lamps, "kerosene", in a rectangular shape with a wick advancing device as part of the mechanism,  have several we use when the power goes out, takes about a minute to get at least 2 going, keep matches with them, all on a shelf in the living room.

jud

[dafi]

I just found a first contemporary hint to this topic:

 

In the book "Nicolas Pocock" from David Cordingly (Conways) there is an interesting remark on page 76.

 

Topic is the painting "The Defense at the Battle of the First of June" and it reports about the historical facts behind:

 

"Midshipman Dillon observed that, 

´The lower deck was at times so completely filled with smoke that we could scarcely distinguish each other, and the guns were so heated that, when fired, they nearly kicked the upper deck beams`"

 

As source is given: "Diary of William Dillon, midshipman in the Defense, Quoted in Warner, The Glorious First of June, p. 79" 

Looks to be from Warner, Oliver, The Glorious First of June, London 1961

 

So perhaps really more than only an invention of modern dramatisation?

 

Cheers, Daniel

Edited March 29, 2014 by dafi

[NMBROOK]

Having recently read Richard Ensor's 'Restoration warship' he does state that recoil was far more violent with bronze cannons,than with iron.An absolute mountain of research went into the book,so I am inclined to agree with him.He doesn't go in to any great reasoning other than to say that many bronze cannon's would develop stress fractures in service which would worsen the problem.I know the time period being generally discussed is perhaps a little later and concerns iron cannons but thought I would add this as it is relevant.

 

Kind Regards

 

Nigel

[Stockholm tar]

Then again, can we actually trust midshipman Dillon's account? He says that at times the lower deck 'was at times so completely filled with smoke', so how can we be sure the guns 'nearly kicked the upper deck beams' as he says?

 

With the 'excitement' of battle, may he not be 'guilding the lily' somewhat in his account – which we can put down to the exuberance of youth? Also, how much later after the battle did he record this – long enough for him to add a little embellishment perhaps?

 

Of course, he may be telling the truth – but I'm not 100% convinced.

[wq3296]

Greetings Folks,

 

Excellent topic and discussion. - many good guesses. Physics are physics. Hot barrel with ambient temperature shot equals more clearance around shot resulting in more blow by. Accordingly, there would be less power applied to the shot and, therefore, less recoil force. Think of your first BB gun. When the piston dried out its diameter reduced and there was less force to drive the BB.

 

Relative to brass guns producing more recoil (or violent jumping) than iron, you have to consider the facts. For a given shot size, what was the relative weight of the respective guns? Of course, gun weight has a bearing on recoil. I am a gun enthusiast, and my .357 revolver kicks much more than my .357 rifle using the same cartridge because the rifle weighs more. As far as the guns changing physical properties when hot, this is plausible up to a point. If you fire a gun long enough, the barrel will distort causing the center line of the barrel to deviate up, down, left or right, resulting in the thrust of the shot (or round) not being directed straight back. I think this could cause a jump instead of a linear push back. I expect that the guns could have been fired to the point of distortion. Although, the barrels would probably have been ruined because they would taken a set after cooling and would not be able to fire straight again. Early machine guns were water cooled to prevent overheating. However, the barrels still needed replacement after a time.

 

I expect that increased gun recoil when hot is a fact, but I think it would relate to barrel center line distortion. The fact that this problem still exists today is a good indicator that it could be responsible for the old accounts of jumping guns.

 

wq3296 

[mtaylor]

After thinking about this... maybe the guns were being double-charged and double-shotted (or even triple-shotted as some have reported) when they closed in?