Strange pattern on target


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Northwest Cajun
January 5, 2003, 11:17 PM
Hi Guys,
A buddy of mine found some strange patterns on his targets the other day. The load is an 95 gr Berry's plated bullet going 1250 fps. The target was about 5 feet from the barrel ( an IDPA match)
Could the strange pattern be from the plating comming off at such a high speed?
Any suggestions would be greatly appreicated

Cajun

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Mike Irwin
January 6, 2003, 12:31 AM
Hum...

Are the bullets lubed?

What color is the bullet lube?

Archie
January 6, 2003, 12:52 AM
bore solvent with some dissolved copper fouling.

But the pattern should not be spiral....

Some other physicist jump in here, but I do not believe that can be the result of ANYTHING being spun radially from the bullet.

Looks like a gag to me.

Northwest Cajun
January 6, 2003, 01:00 AM
`Mike,
Plated bullets are not lubed and this was not from the first stage of the match so we can rule out solvent.
No gag, He said it had a metallic sheen.
I had to reduce the photo as it was really large. I'll try to post it bigger .I'll try to get a little more detale

Please keep the replys comming
Cajun

Northwest Cajun
January 6, 2003, 01:08 AM
It's a little bigger.
Cajun

HSMITH
January 6, 2003, 09:12 AM
That sure looks like lead particles being spun off to me. I have only shot hot loaded lead a couple times and from what I found in the barrel after a few rounds I can believe that lead wil be coming off the bullet for a few yards downrange. Hard to say though without the target in hand.

DamnedDirtyApe
January 6, 2003, 10:24 AM
1200 fps is pretty much the top end for plated bullets, and perhaps far too fast for your 95 grainers.

Berry's will often shed their plating as they leave the muzzle if you push them too hard.

Load them like straight lead and things should improve.

Mal H
January 6, 2003, 10:31 AM
Here's my "I'm not there to look at it closely and ask questions" guess.

The almost-circular spirals make approx. 1/4 turn and show signs of dissipation the further out from the bullet they are. That means the vapor is flowing out somewhat constantly from the bullet itself and is retaining some, but not much, of the angular velocity of the bullet. That suggests the vapor is slightly heavier than air or burning powder gasses. The apparent 1/4 inch turns implies that the vapor shown on the target was the vapor that spewed out in the 3 to 6 inches just before the bullet hit the target, depending on twist rate. The vapor before that is probably dissipated enough so that it doesn't collect on the target.

The color is just about right for an oxide of copper with some whitish overtones suggesting lead is also a component.

My best guess is that the grooves in the bullet are still extremely hot from friction at that short of a distance from the muzzle causing the copper plating (copper wash?) and even some lead underneath to vaporize and spew from the grooves of the spinning bullet.

Note that one groove is not emitting any vapor (the one at 7 o'clock on the right bullet hole). You might want to check the gun used to see if one land is shinier than the others (less friction) or see if there is any evidence of why one land would be acting differently on the bullet.

Northwest Cajun
January 6, 2003, 12:06 PM
Thanks Mal H

Cajun

Mikul
January 6, 2003, 03:29 PM
The lead under Berry's bullets is fairly soft so if the round is pushed fast enough, it will begin wearing the very thin copper plating. I've never seen the plating vaporize like that, but I have seen pitiful accuracy due to the plating ripping off.

I've never pushed Berry's that fast.

FYI, he didn't make the power factor for IDPA. He's only at 118 instead of 125. He needs to push it to 1,316fps. Please post the pictures of that impact if there is one.

bigjim
January 6, 2003, 10:43 PM
You have been shooting the infamous Spiral death cop killers.
They will "buzz" right through a kevlar vest!.

Jim

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