Firing guns

[PhilB]

After the documentary on submarine M1 last night, I had a look in Jane`s. The sub sailed at periscope depth to fire its 12 inch gun, the gun being aimed through the periscope. What I wonder is - what happens if seawater gets into the barrel? Or, for that matter, if water gets into any gun barrel. Can it still fire, or does the incompressible liquid cause barrels to burst? Phil B

[MikB]

A cubic foot of water weighs about 63 lb. Added to a projectile of around 900 lb. weight, the safety margin would have to be slim indeed for this to damage the barrel, though it may well reduce velocity and increase recoil, annihilating accuracy at anything more than point blank range.

On the other hand, a barrel full of water for a 12"/40 cal. gun would weigh about 1920 lb., more than tripling the weight the propellant has to shift, and I'd be very surprised if that didn't have pretty catastrophic results.

So the issue really has to hinge around: how much water are we talking about?

Regard,

MikB

[PhilB]

Hard to say with a sub travelling at periscope depth and the 12" barrel protruding from the water!

What do you reckon would happen if you tried to fire a rifle with a barrel full of water?

[Tom Morgan]

Did they have some kind of waterproof plug fitted? Would that keep the barrel free of water when submerged and if so, might it still be possible to fire the gun? (Even if it was, I think that accuracy and impact would have been anyone's guess).

Tom

[michaeldr]

Quote: Or, for that matter, if water gets into any gun barrel

Heard of a chap who turned his M16 into an umbrella frame by trying to shoot fish with it

Apocryphal story? I don't know,

I knew the fellow and think him quite capable of it

Heard the CO was not impressed either

[PhilB]

Tom, the plug would work - but only for the first shot. I seem to recall the M1 had to surface to reload. I can`t see why other than to replace the plug!

Firing with water in the barrel must have been a hazard for many in WW1, I would have thought. Phil B

[Tom Morgan]

QUOTE (Phil_B @ Sep 12 2006, 02:04 PM) <{POST_SNAPBACK}>

Tom, the plug would work - but only for the first shot.

A fact which escaped me, Phil! Yes - you would only get one shot. Even then I think there might have been serious problems with the gun expelling the shot and gas into water, when it was designed to expel into air. Firing guns underwater seems very risky to me.

Tom

[MikB]

Our old RSM used to say that firing a 303 with wet ammo - or a small amount of water in the barrel - would raise the POI by a foot at 100 yards; presumably because the weight of the water slows the bullet, which then emerges from the muzzle later in the recoil cycle.

Again, a barrel full of and immersed in water is bound to be a more serious proposition...

Regards,

MikB

[michaeldr]

Phil,

have you had a look at http://www.navweaps.com/Weapons/WNBR_12-40_mk9.htm

quote: Three of these guns were later used on the "M" class submarines. These were meant to be utilized as anti-shipping weapons, as it was felt that a single hit from a 12" (30.5 cm) projectile would be enough to sink a merchant vessel. This was moderately successful, although if the firing tube leaked, the muzzle could be blown off the weapon.

and

quote: The submarine gun could only be reloaded on the surface. The procedure was to do a submerged approach a target to within 1,200 yards (1,100 m), drive the submarine to the surface, quickly fire the gun and then dive back down. It is apparently a myth that the gun would normally be fired with only the muzzle out of the water when attacking an enemy, as such a condition would mean that the gun was at its maximum elevation while the sighting periscope would be at a minimum height out of the water. Such a combination would mean an extremely slight chance of hitting anything.

and

quote: The submarine mount needed to be loaded and fired on the surface, although some trials had just the muzzle of the gun above the water. The muzzle was fitted with an electrically-operated, water-tight tampion. The gun mounting was free-flooding, thus allowing quick access after surfacing.

[PhilB]

So steps were taken to ensure that water didn`t enter the barrel. And the the gun was not fired from periscope depth, as the programme indicated. I gather, from the above, that to reload, the sub surfaced and the crew came out on deck?

It looks like water in the barrel is a no-no for any type of gun/rifle? Phil B

[MikB]

QUOTE (Phil_B @ Sep 12 2006, 03:47 PM) <{POST_SNAPBACK}>

It looks like water in the barrel is a no-no for any type of gun/rifle? Phil B

You might get away an effective shot where accuracy isn't critical and there's a small amount of water, but the more there is, the less effective the fire and the more likely is damage to the gun - and maybe the shooter/crew.

Did these 12-inchers ever blow up, and if they did, did splinters penetrate the pressure hull?

Regards,

MikB

[lionboxer]

It sounds like a recipe for disaster to me. ANY foreign body in the barrel of a gun during firing can have catastrophic effects. A friend of mine was shooting pigeons from a bale hide and unknowingly got a bit of straw in the barrel when reloading. Upon the next discharge the barrel bulged but luckily did not burst as he could have lost his fingers or worse, and that was only straw. My old weapons instructor repeatedly told us to check for obstructions in our rifles. How a larger calibre weapon would fare I don't know but I remember reading that if any guns were to be spiked the barrels were plugged before firing. Another point is that water doesn't compress and would act as a brake to the projectile in the rifling of the barrel.

Lionboxer

[J T Gray]

IIRC I have a book with a photo in it of M1 firing a first shot after surfacing which took the muzzle off the barrel. I'll take a look tonight!

Adrian

[CSMMo]

In field cannons (different weapon - but internal ballistics are consistent throughout all firing pieces in some regards) we weren't allowed to even have mud on the projectile prior to loading and, even though the preceding round caused so much commotion that it lifted our 26 ton track up with its recoil, a gunner was required to peer into the tube after each round was fired and shout out "bore clear!" (which led to a lot of bad jokes amongst gunners).

Water in the barrel? As stated earlier, a recipe for disaster. Even firing into water with a plugged barrel would alter the ballistics so much that the round would be all but unpredictable. (IMHO, of course.)

Mike Morrison

[Northern Soul]

Some years ago I worked for MoD(PE) at an artillery proof and experimental establishment. To proof test L20 (120mm tank gun) "tubes" we used to fire "water shot" - waxed cardboard cylinders filled with tap water - 3-off per test. Admittedly, the increased barrel wear due to the steam and hot water created was supposedly equivalent to, I think, firing three proof rounds at full charge and it only tended to be fired from barrels that were nearing the end of their useful lives but there was no safety issue. We never used to take cover when the gun was being fired.

I do recall a tale of one individual though who inadvertently left a bore sight in the end of another L20 during an armour trial. Didn't see it myself but apparently the result was quite spectacular. Could have been the same character that left a crusher gauge in the breech of a 105mm Light Gun during its proof test firing and then supervised the loading of the next round. I don't think that gun ever saw active service - by all accounts RoF Nottingham had to scrap it. To say he was in the 'doghouse' because of that incident would be an understatement.

[johnreed]

All new guns were tested with water shot it is noted on the Barrel History sheets the first enteries where the EFC's were logged.

John

[J T Gray]

IIRC I have a book with a photo in it of M1 firing a first shot after surfacing which took the muzzle off the barrel. I'll take a look tonight!

Adrian

Oh flatus, I forgot didn't I? If anyone is interested, PM me and remind me!

Adrian

[J T Gray]

From "HM Submarines in Camera - An Illustrated History of British Submarines 1901-1996" by Commander J. J. Tall and Paul Kemp.

Adrian

[PhilB]

I`m confused now, guys. You can fire a water filled charge, but if water leaks in, you can blow the end of the barrel off? Phil B

[CSMMo]

Pressures!

I would say there might be some differences between firing a weapon in a depot or test situation and firing it in service. The depot boys know what they are doing and they must have a reason for the water filled rounds, but once in the field, there must be no foreign obstacles or debris in the tube or on the round. My battalion suffered a "blown tube" which seriously injured the three gunners inside the howitzer (M109 155mm) at Ft. Irwin, CA in the 1980's. It was theorized that they fired a projectile with a hairline crack that detonated prematurely, however, those kinds of incidents tend to make one follow the prescribed safety rules quite closely. And the precribed rules are - clear bore, clean round properly fuzed with the correct charge. I've seen WW1 film of gunners wiping off projectiles before loading just as we still do.

Mike Morrison

[Tom Wales]

As WW1 German U-boats used their deck guns to sink merchant shipping , how did they avoid these problems when they frequently had to dive quickly? Did they use muzzle covers? Also how did they avoid corrosion issues?

[PhilB]

Good question Tom. Did U-boats and subs get many split barrels?