Curious case of the shrinking bullet

[pettypace]

Although this mystery has been solved to my satisfaction, for the sake of discussion (and for those who enjoy solving puzzles on their own) I'll withhold my solution and provide only some of the clues.

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These two bullets are shown just as they were cut from the same well-used brick of Clear Ballistic gel. They came from the same lead pot, dropped from the same mould, and were fired with the same powder charge from the same .44 Bulldog snubby. The bullet on the left is the expected .43 caliber. The bullet on the right is closer to .40 caliber and now drops freely through the Bulldog barrel.

Finally, the 2 o'clock void in the bullet on the right is an embarrassment -- not a clue. No further comments on that are required.

[lar45]

Can we see a side profile of the boolits in question?

[pettypace]

Can we see a side profile of the boolits in question?

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[onelight]

You got me , I have no idea what would cause that.
I will have to watch and learn.

[Rich/WIS]

There are noticeable differences in the width of the driving band and length of the portion forward of the driving band. Are you sure these are the same bullet? Even if the bullet were deformed on impact don't see how the driving band would get longer.

[Drm50]

This was suppose to occur firing same bullet as dropped through same 44 Bulldog? Discounting the driving band issues the only thing I can think of is stratified alloy. Bullet on right looks to be coarse cast which is usually high zinc content. That doesn't make sense with the difference in the slugs measurements.

[pettypace]

There are noticeable differences in the width of the driving band and length of the portion forward of the driving band. Are you sure these are the same bullet? Even if the bullet were deformed on impact don't see how the driving band would get longer.

Yup... Same bullet, for sure.

[pettypace]

This was suppose to occur firing same bullet as dropped through same 44 Bulldog? Discounting the driving band issues the only thing I can think of is stratified alloy. Bullet on right looks to be coarse cast which is usually high zinc content. That doesn't make sense with the difference in the slugs measurements.

Not sure what you mean by "dropped through same 44 Bulldog." But to clarify: They were both shot through the same .44 Bulldog and now the skinny one will fall right through the barrel. Both bullets were cast from the same alloy. The change occurred after pulling the trigger and before cutting them out of the gel. And there were no "barriers" between the barrel and the gel.

[C. Latch]

Did one of them slam into the other in the gel?

[Drm50]

Sorry, I meant bullet was used as dropped from mold, not sized. Thinking if everything was the same until fired through Bulldog the only reasonable thing would be a undersized chamber in cylinder.

[pettypace]

Sorry, I meant bullet was used as dropped from mold, not sized. Thinking if everything was the same until fired through Bulldog the only reasonable thing would be a undersized chamber in cylinder.

I should have mentioned that both bullets were sized and lubed through the same die.

As for an undersized chamber... Well, it is a Charter Arms. But no. A bullet sized to .430, as these were, can be eased through all five chambers without sizing or rattling.

[pettypace]

Did one of them slam into the other in the gel?

Nope!

[Drm50]

I'm curious to see how bullets of same diameter, fired through chambers of .430+ through same barrel can end up a smaller diameter by .030".

[JonB_in_Glencoe]

Crooked launch would be my first guess, have you checked for runout on any remaining loaded ammo?

Poor lockup is my second guess (The cylinder not perfectly aligned with barrel during firing).

[pettypace]

Crooked launch would be my first guess, have you checked for runout on any remaining loaded ammo?

Nope. Ammo was pretty well loaded with special attention to bullet alignment while seating and crimping.


Poor lockup is my second guess (The cylinder not perfectly aligned with barrel during firing).

And no. Although I have been abusing it, the Bulldog is relatively new and still pretty tight. But enough of these loads could change that.

[pettypace]

The skinny bullet in question was the tail end of a two-projectile load I was testing. The two bullets were stacked base-to-base as shown below. The nose of the skinny bullet was facing the powder.

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[JonB_in_Glencoe]

So ...the "tail end" boolit got swaged down by the case?

[reddog81]

The internal taper of the case swaged it down.

What weight are the bullets? That looks like a lot of lead to stuff into 1 case.

[Drm50]

Why didn't you say it was a double load in first place? O

[pettypace]

The internal taper of the case swaged it down.

Nope. They seat in the case just fine. No swaging and no bulging of the case.


What weight are the bullets? That looks like a lot of lead to stuff into 1 case.

Bullets are 160 grains each and seated deep in the case. So the load has to be approached judiciously. I won't bother testing this particular load again -- not because it's too heavy but because there's nothing good about shrinking bullets.

[pettypace]

Why didn't you say it was a double load in first place? O

Why? Does that explain the deformation of the bullet?

[pettypace]

So ...the "tail end" boolit got swaged down by the case?

No. The boolits seat OK and don't even bulge the cases.

[bigted]

I would bet that that load would lead terribly. Think gas cutting on the rear boolit because of the smaller nose and tapered nose.

CLOSE?

[pettypace]

I would bet that that load would lead terribly. Think gas cutting on the rear boolit because of the smaller nose and tapered nose.

CLOSE?

Yes! You'd win that bet on the leading! Serious gas cutting -- apparently along the whole length of the boolit as it goes down the barrel. If you google leopold bullet stretching the first hit is an issue of Shooting and Fishing circa 1901 with a related blurb.

Note how the base of the skinny boolit was burned. So the gases made it in between the two boolits. Interesting, in the gel testing of five shots, four averaged about 600 ft/s and for one shot the chrongraph showed over 700 ft/s. I figured it was a chrono error because I didn't notice any difference in recoil or report and the Bulldog was still in one piece. But my guess is that the gases squirting past the skinny back boolit gave the front some extra velocity.

[bigted]

Interesting.

I once thought briefly about loading my 1860 with .454 boolits backwards so they would load straight. BUT ... then I began contemplating gas cutting around the tapered nose and did not try it because of uncertain pressure.

[pettypace]

Interesting.

I once thought briefly about loading my 1860 with .454 boolits backwards so they would load straight. BUT ... then I began contemplating gas cutting around the tapered nose and did not try it because of uncertain pressure.

The tapered nose probably doesn't help. But I suspect the narrow (0.040") front band (which becomes the base band) may be the real culprit. In the .38 Special, I've shot plenty two-projectile loads with two Lyman 356404 boolits stacked base-to-base and never had any gas cutting. Same tapered nose, but the front band on the 356404 is more like 0.090".

[bigted]

So is this where you went for your conclusion on the mysterious shrinking boolit?

[pettypace]

So is this where you went for your conclusion on the mysterious shrinking boolit?

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[JonB_in_Glencoe]

Nope. They seat in the case just fine. No swaging and no bulging of the case.

>>>SNIP
Just because there wasn't any bulging, doesn't mean they weren't swaged down.
So you pulled some from the same brand of cases that gave you the elongated boolit, and measured them?

[reddog81]

Are you saying the pressure of the gases on the side of the bullet squeezed it and made it longer? If so, there’s no way that’s possible. The pressure on the front and rear of the bullet would be the same and keep that from happening

I just measured some 44 Mag cases. The internal taper of the case goes to .41 at .75” deep. A 320 grain .44 Mag bullet is .85” long. With a soft bullet the lead will just swage down.

[pettypace]

Are you saying the pressure of the gases on the side of the bullet squeezed it and made it longer? If so, there’s no way that’s possible. The pressure on the front and rear of the bullet would be the same and keep that from happening

Gases don't get to the front of the bullet right away. What do you figure happens when gas gets into the first grease groove? Pressure radially inward can squeeze the bullet down. The lead can flow forward increasing bullet length.






I just measured some 44 Mag cases. The internal taper of the case goes to .41 at .75” deep. A 320 grain .44 Mag bullet is .85” long. With a soft bullet the lead will just swage down.

I'd be surprised if you could seat that 320 grain bullet to a depth of .75" and still chamber the cartridge. At any rate, my seating depth is closer to 0.55" not counting the tapered nose.

[pettypace]

Just because there wasn't any bulging, doesn't mean they weren't swaged down.
So you pulled some from the same brand of cases that gave you the elongated boolit, and measured them?

No. Actually, I inertia pulled the fronts and shot out the rears. No measurements.

But out of curiosity I just resized one of the cases, seated a couple of the same truncated cone bullets, and inertia pulled them. The pulled back bullet measured the same 0.430" as when I loaded it. No swaging by the brass on seating.