Mega Hollow Points?

[John917]

I am curious, has anyone else pulled the polymer tip on rifle shells, and fired them, (in short, they look like hollow points with really deep cavities)? I did that on some of my .17 HMR bullets, but I am scared to shoot them, I think they might have so much drag that they expand in the barrel, and mess it up. But, if they do work, I am thinking they may work well on hares and other similar-sized game. Please help.

 

[Deer Hunter]

Are you talking about taking the polymer tip from a ballistic tip bullet?

If so, I believe that the polymer doesn't do much for the bullet integrity once it hits a target. In fact, it's mainly their so the rifle will feed it reliably.

Anyone else have a different take?

 

[Zundfolge]

I'm with Deer Hunter on this one. The little plastic tips will push into the bullet on impact and aid expansion anyway, so removal isn't really necessary (and may make them less accurate, especially on a light weight bullet like a .17).

I do, however, doubt that air pressure will cause them to expand in the barrel.

 

[the naked prophet]

Expansion can't happen in the barrel, even if you fire underwater. I can explain if you want, but it'll be long and involve aerodynamics and aerophysics.

 

[falling leaves]

The polymer tip is there for ballistics. IIRC Nosler's are called 'Ballistic Tips".

A lead nose is easily deformed by rough handling, which would change the balance and air resistance in flight, and make the bullet fly differently than any other round. Full metal jacket points are harder than lead, but can still deform, and are not the choice for hunting rounds due to terminal performance. Take a look at a box of 20 soft points and see how many of them look identical. You won't find too many.

The polymer tips on premium rounds will bend when they get knocked around, but then spring back to their original shape. This means (theoretically) that each and every round fired will fly the same, which gives better accuracy, especially at longer ranges.

The polymer is definitely NOT holding the jacket together in the barrell.

It would be interesting to see some comparisons between groups with and without the tips. I'm guessing the ones with out will drop quicker due to higher air resistance, and should show a wider dispersion. Anybody have a 300 yard range, a bench, spare time, and money to burn?

 

[John917]

OK, I feel better about shooting the bullets I 'modified' now. As soon as I go hunting, or target-shooting (whichever comes first), I'll try it, and report back. Thanks for the help, everybody. You know, I noticed one thing about this site, everybody is nice/helpful, or they don't say something at all. This R.C. monster truck website was full of jerks. As soon as a newbie asked a 'simple/stupid' question, the know-it-alls would cuss them out, or just discourage them. Then, we have this site, where people talk about firearms (in an orderly manner), something that many people erroneously associate with violence, crime, and 'bad guys', outside of which I couldn't find a friendlier, more helpful bunch of people. (Sarcasm on) I think that shows how 'violent' gun enthusiasts can be, huh? (Sarcasm on)

 

[tnieto2004]

A barrel can't bulge underwater??? I thought they had test that proved they could??

 

[falling leaves]

John917 - I think that "The High Road" is a very appropriate name for this site. I too like the well moderated adult discussion, information, and advice that is available here. Glad to have been able to contribute a little.

 

[rcmodel]

I have shot a few .223 Nosler BT's that had the tips broken off, out of an AR-15.

Nothing bad happened, but I didn't test them for accuracy.

On the otherhand, I agree that removing them probably is not going to make any differance in expansion. They already blow up like small bombs with the tip in place!


rcmodel

 

[Silvanus]

As soon as I go hunting, or target-shooting (whichever comes first), I'll try it,

I'm not sure about this, but should you not at least try them for accuracy before you go hunting with those rounds? Just a few rounds to make sure you hit what you aim at...

 

[351 WINCHESTER]

The ballistic tip on the 17 and many other calibers is mainly for accuracy, aerodynamics and feeding. I doubt it has much to do with expansion though.

 

[the naked prophet]

A barrel can't bulge underwater??? I thought they had test that proved they could??

No, I said a JHP bullet won't expand in the barrel. The barrel could easily bulge, especially in a larger caliber which would have to push a larger mass of water out the barrel. Same as putting a much heavier bullet in the case than the loading manual says - it'll create much higher pressure.

But the bullet won't expand in the barrel!

 

[Glock19Fan]

Just curious, but why not?

I was always told not to shoot JHPs if you are shooting underwater (specifically Glocks) becuase the bullets may expand inside the barrel.

I hungry for some knowledge.

Thanks!

 

[John917]

I wouldn't hunt with them until I knew how they worked, but I would try them out on targets when the hunting got slow. Whoops, I forgot to specify.

 

[The Deer Hunter]

If so, I believe that the polymer doesn't do much for the bullet integrity once it hits a target. In fact, it's mainly their so the rifle will feed it reliably.

Anyone else have a different take?

I tried reading all the responses but didn't get them all so here goes. The plastic tip is used to keep the bullet accurate, as the hollow nose on a HP bullet causes more drag and such. Also, with the new leverevolution ammo(however you spell it) uses the plastic tip as to keep the bullet pointy and keep it in a lever action rifle with a tubular magazine.

 

[righteousbarbarian]

please correct me if i'm wrong, but i think bullets can't expand inside barrels because the majority of the gas pressure that is exerted on them is coming from the powder charge, which is in the rear of the bullet. the powder charge creates a lot of gas pressure on the rear and, perhaps to a lesser degree, the sides of the bullet as it passes through the barrel. the pressure exerted on the front of the bullet where the hollow point is as it passes through the air is much less than the pressure that is exerted on the rear of the bullet. This is why the bullet accelerates forward out of the barrel so quickly and why the hollow point will never expand in the barrel.

 

[benEzra]

I was always told not to shoot JHPs if you are shooting underwater (specifically Glocks) becuase the bullets may expand inside the barrel.

Simple answer--because for the bullet to even begin to move down a barrel filled with water, the water has to accelerate as a unit along with the bullet. There is no relative motion between the bullet and the water in the barrel; they move together.

Also, for hydrostatic reasons (Pascal's principle), the pressure of the water on the bullet produces no net radial force that could produce expansion. Once the bullet exits the barrel, hydrodynamic effects come into play that can cause expansion, though.

If the extra mass from the water in the barrel slows the bullet down enough, though, the barrel can fail from overpressure behind the bullet. But it's not from the bullet expanding.

 

[Bobarino]

but it'll be long and involve aerodynamics and aerophysics

Prophet,

don't you mean hydrodynamics and hydrophysics?

Bobby

 

[the naked prophet]

Air and water are both fluids - the same principles apply to both, and both are referred to as aerodynamics - at least in the mechanical engineering field.

Okay, the brief explanation:

Any moving fluid has a quantity associated with it - a quantity such as velocity, momentum, etc. One of those quantities is called the "stagnation pressure." It's actually a measure of energy, not pressure. Stagnation pressure, or Ps is the pressure a fluid would be if the flow was completely stopped (ie. all its kinetic energy was converted into pressure), such as a fire hose spraying directly onto a brick wall.

When a fluid is moving past a JHP bullet (considering the bullet to be our fixed frame of reference), some of the fluid comes to a complete stop in the cavity - this is the realization of the stagnation pressure, and one of the few instances where it actually occurs. As speed increases, so does the kinetic energy of the moving fluid. However, water is much more dense, which means that the kinetic energy of water moving at the same speed as air is going to be much higher - therefore the stagnation pressure will be much higher. That's why a JHP hitting water (or flesh) will expand, but it won't expand in air.

When you fire the bullet under water, the entire slug of water in the barrel moves along with the bullet - there is the same pressure on the entire face of the bullet, including the inside and outside of the hollow cavity. Once the bullet exits the barrel, the water surrounding the bullet is no longer moving at the same speed as the bullet. As soon as that happens, the pressure inside the cavity increases due to the stagnation pressure, and the pressure outside the bullet is the normal pressure - the higher pressure inside the cavity makes it expand.

 

[Bobarino]

Air and water are both fluids - the same principles apply to both, and both are referred to as aerodynamics - at least in the mechanical engineering field.

air = highly compressible

water = nearly noncompressible

big difference. different physics, different dynamics. many fluid laws apply to both, but they are definitely not the same.

Bobby