'Air pulled' bullets?

[chris in va]

Can someone explain the process? My Google-fu is on vacation today.

 

[Don H]

I'm sorry but I haven't heard that term before. Where did you hear/read it?

 

[Unclenick]

Don,

Some of the surplus pulled bullet sellers use the term, but they don't explain it that I've seen.

I don't know the process, either, but I'll take a guess at the principle. Much of the foreign ammo I've pulled doesn't have sealed bullets, so you could put these cartridges in a chamber and pressurize it long enough to get compressed air to bleed into the cases. Then you'd open a big valve to drop the chamber pressure abruptly, letting the pressure in the cases push the bullets out.

I'd have to experiment to find the actual pressure requirement. It should be somewhat less than is required to achieve normal pulling force on the bullet, as the compressed air would not only push the bullet, but would tend to loosen the neck's grip on it.

You'd want to use dried and oil-free compressed air if you intended to salvage the powder and primed cases. If not, if it's corrosive Berdan primed brass charged with old powder, for example, then anything will do. I would not expect this principle to work with pitch-sealed US made ammo.

And, of course, I could be completely off base. It's just a guess.

 

[medalguy]

I contacted one of the sellers of "air pulled" bullets and he admitted he had no idea either. He said that's the term used by his source for the bullets.

I'm a little leery of buying something no one can explain to me.

 

[rg1]

I've heard that the air pull process works just like a reloaders kinetic puller that you whack against something like using a hammer, except the air puller uses air pressure for the force to move the "hammer" to pull the bullet. Wouldn't know if it would use air operated cylinders or a piston for the inertia. Just what I've heard with no proof whatsoever.

 

[Inspector3711]

I've always thought it would be a pnuematic powered chuck that clamps down on the bullet...... Not sure though.

 

[rg1]

Check out the post by" FECMECH" at this site:
http://forums.1911forum.com/showthread.php?t=207432
Seems a friend welded a shellholder to a chisel on a pneumatic tool to pull bullets.

 

[Unclenick]

I guess I don't think that would work as it was described. There's no more reason for inertia to pull the bullet out than there is for it to seat it deeper if the strokes are equal in acceleration in both directions. But maybe they aren't. I've never pulled one of those air chisels apart, but I'd expect the forward stroke to be the one that needs speed. So if that's the case, out fast, in slow, maybe if the shell holder was welded on backward it could work.

 

[Miata Mike]

I just bought some 55 grain .223 fmj bullets that were "air pulled" and they look excellent. Not sure why these cartridges were disassembled for parts instead of left whole.

 

[Clone]

welded a shellholder to a chisel on a pneumatic tool to pull bullets

That sounds like an IDEA.

 

[Unclenick]

Mike,

Cartridges can get too old. The powder eventually deteriorates. I had some Czech .308 surplus one time which were terribly inaccurate and about 5% would fire very weakly. When I pulled a few I found the powder in a lot of them was clumped together, which is one kind of deterioration symptom. Too old. In addition, these were corrosively primed Berdan brass. Only the bullet was salvageable unless I wanted to shoot the corrosive primers, and even then it took some work to get the sticky powder out. Not worth the effort.

 

[Don H]

I just bought some 55 grain .223 fmj bullets that were "air pulled" and they look excellent. Not sure why these cartridges were disassembled for parts instead of left whole.

I vaguely recall reading that sometimes the sales contract for surplus ammo specifies that the cartridges must be disassembled prior to resale.

 

[bearol63]

I asked a supplier what it meant and this was his reply - "Pulled bullets are retrieved from military ammo using a machine that either pinches or sucks out the bullet. The ones with no pull marks were sucked out. The others were pinched"

 

[Unclenick]

I wouldn't believe that for a second. He made it up. It takes about 60 lbs to pull a typical bullet. More if it has aged awhile in the case. Up to 600 lbs pull has been measured at Aberdeen Proving Grounds for aged cartridges. Atmospheric pressure is only 14.7 lbs per square inch at sea level. Multiply that times the bullet cross section area and you have 1.09 lbs push on the base of a .308 in a perfect vacuum, and 0.58 lbs on a .224. I can apply more pull than that with my fingers.

I was figuring it would take more like 50-100 atmospheres driven inside the case to pull a typical bullet by my first proposed mechanism or in a vacuum (not much difference between vacuum and atmosphere when you have that kind of pressure inside). 1500 psi or so for .223. But I don't know how much to allow for case expansion. The pneumatic method seems easier to construct, but more work to use, being one-at-a-time, where a chamber would let you batch process. Either way, you'd have to like cleaning up spilled powder.

 

[Miata Mike]

Mike,

Cartridges can get too old. The powder eventually deteriorates. I had some Czech .308 surplus one time which were terribly inaccurate and about 5% would fire very weakly. When I pulled a few I found the powder in a lot of them was clumped together, which is one kind of deterioration symptom. Too old. In addition, these were corrosively primed Berdan brass. Only the bullet was salvageable unless I wanted to shoot the corrosive primers, and even then it took some work to get the sticky powder out. Not worth the effort.

OK, that makes some sense Unclenick.

 

[medalguy]

I like unclenick's explanation. Additionally, if a vacuum puller were used, would not that also cave in the sides of the case until the bullet came out? Something has to replace the reduced volume inside the case when the bullet moves forward.