Question about firearm physics for my screenplay.

[Switchback]

Why would you have to rack the slide to clear water out of your barrel???

[missouricop]

Why would you have to rack the slide to clear water out of your barrel???

In theory, submerging the gun in a deep pool there is no exact way of telling what direction the gun will fall (sink). The possibility of water trapping in the barrel due to air lock from the casing sealing the breach end and the open mussel end allowing water in ( if it sank mussel up or at an angle lessor than 90 degrees.)

keeping the water air locked in it could prohibit the bullet from passing quickly out of the barrel, pressing the water together loading up a water barer in front of the bullet causing enough water in front of it to give water tension before exiting the barrel.
Giving the belly flop water surface tension effect. Racking the slide, (ejecting the casing and breaking the seal to unlock the air lock.)

Preventing this a common practice was used in the military. Putting a condom on the mussel and down the barrel was to prevent this not rust. Shoulder strap mussel in the air long march in the rain. Going from shoulder to firing position keeping the barrel full of water.

Again this is a theory, not saying its true. I am not saying I believe it.

but stranger things have been used in movies and believed by thousands.
Also makes a good what if movie topic.

[Switchback]

Guns are not manufactured so precisely that the water will only dump out the front of the muzzle. Iven with my customed 1911, the parts do not fit so precisely that you have to worry about water getting "air locked" in there. It will be coming out of the ejection port and mag well, too. In fact, if there were ONE thing that I would do, it would be dropping the mag and getting water out of it. In all honesty, I think that you would be able to get rid of most water by simply tipping the gun a time or 2 and shaking it.

We always used the covers over out flash-hiders to keep the sand out. That crap got everywhere. I really don't think that having a condom snugly fit over the muzzle end (or a cover designed for this use) would still not prevent water from filling the guns innards when you submerge it.

[harmonica]

If you have him recover the gun and chamber another round (to clear the water in the barrel )
some guy who thinks he is the worlds smartest film critic, is going to say " Thats just crap. Why would a cop not already have one in the hole?" If you don't, then you have tha guy saying, Water can be still in the barrel and can obstruct ( the whole water surface tension thing)

6 of one 1/2 dozen of the other

I would suggest him saying something about it has he chambers a new round .
But your the writer.

What if I had him wrote that after he got the gun out of the pool, he then shoots but it does not fire. He then chambers the next round to clear the water and it does. Does that sound right?

[Switchback]

What if I had him wrote that after he got the gun out of the pool, he then shoots but it does not fire. He then chambers the next round to clear the water and it does. Does that sound right?

NO. In all probability, one casing leaked water, several would. If the first round went off and there were a lot of water in the barrel, it would likely result in a catastrophic failure... there would be no second round.

[Movementarian]

NO. In all probability, one casing leaked water, several would. If the first round went off and there were a lot of water in the barrel, it would likely result in a catastrophic failure... there would be no second round.

Indeed, if the first one didn't work it would be time for a reload. At least it would for me.

[Switchback]

Indeed, if the first one didn't work it would be time for a reload. At least it would for me.

Reload with dry ammo or go see the doctor for a sore hand (with too much water in the pipe).

[harmonica]

Alright I'll write it so he has to reload after recovering it. Guess that movie No Country For Old Men, got it right.