Stability of traditional pistol bullets when fired into water from an unrifled barrel

[.455_Hunter]

Questions for all you terminal ballistics experts out there…

All NFA considerations aside, how will the trajectory of a traditional “bullet” shaped projectile behave in water if the projectile is NOT stabilized by rifling?

For example, let’s say a .38 special 158 gr Round Nose FMJ is fired at standard velocity from a unrifled barrel into a Fackler box. Is there a reasonable likelihood of the projectile exiting the box at a deflection up to nearly 90 degrees?

Something like this could occur by shooting “modern”.38 Long Colt ammo with a flat base .357 diameter cast bullet out of a pre-1903 Colt New Army with a .375 diameter bore, or firing a oringal Liberator with its smooth bore barrel.

Thanks for your input.

Hunter

 

[MAKster]

No idea what a Falker box is, but a bullet entering water would not be deflected at a 90 degree angle. 30 degrees seems more likely.

 

[.455_Hunter]

No idea what a Falker box is

Sorry- A Fackler box is typically a wooden box holding multiple water filled gallon baggies designed to evaluate bullet performance.

 

[GRIZ22]

You mean a Fackler Box?

 

[.455_Hunter]

You mean a Fackler Box?

Yup! Edit to correct...

 

[rcmodel]

No bullet is likely to make a 90 degree turn, unless it glances off a hard object at 45 degrees to direction of travel.

Your un rifled bullet would be totally unstable, but would tumble and probably end up stopped going backwards, because the base is heavier then the nose.

Thus, a center of gravity biased toward the base.

rc

 

[Haxby]

If you look at youtube videos of ammo tests in gel, every once in a while they lose one out of the side or top of the block. With an unrifled barrel and separate bags, it definitely could happen. No idea how often.

 

[strambo]

I agree, a 90 deg turn isn't going to happen. Besides, every bullet is unstable in water, the twist rate isn't high enough to stabilize them in such a thick medium.

When bullets exit gel and water jugs etc, it is because they deviate a few degrees from the path of travel due to being unstable in the media, they don't make 90 deg turns.

If anything, the bullet tumbling in air may go straighter in water. It is set in its unstable tumbling motion already when it hits. Rifled bullets are hitting stabilized and making a transition to unstable resulting in deflection. Just my SWAG though.

 

[481]

If you look at youtube videos of ammo tests in gel, every once in a while they lose one out of the side or top of the block. With an unrifled barrel and separate bags, it definitely could happen. No idea how often.

Lots of tests end up like that, you are right. Clear gel, ordnance grade stuff, it's always a dicey proposition.