Bullets in flight

[Tozguy]

The Kurzzeit video in a recent Daily bulletin is spectacular!
Besides providing observations of bullet 'behaviour' on impact, it provides new (to me) views on what a bullet looks like after it has exited the barrel. We have had pictures of the inside of a barrel from using borescopes for a while now but getting a look at the bullet after it has travelled the bore has always been evasive (not to mention expensive). Analysis of the marks and deformation of the bullet after travelling the barrel will probably help us eventually to better understand what happens in the bore. Just wondering if the bullets look like what you have been imagining or has something in particular impressed you about the look of the bullets in the pictures.

 

[jo191145]

What I found interesting is the tiny amount those pistol bullets seemed to be deflected by the BB's. I would have thought it would be more.
I imagine the effects would be more pronounced further on down range. Part of that is obvious of course ;D
I wonder how much deflection occurs from the initial impact and how much is the result of the deformed bullet in flight?? First question is how much overall deflection is there.

For my own ha ha's I'd like to see a 39BK fired out of one of my 204R barrels. Had lots of issues with those over the years in several barrels. I have theories as to whats happening but without video they're just theories

 

[Tozguy]

Joe, I'm curious about your theory if you feel like sharing it with us.
Mike

 

[bozo699]

I saw that video a year or so ago but enjoyed it again,it gives a all new meaning to what happens to your bullet from muzzle exit to target impact to target exit. Technology is amazing!
Wayne

 

[jo191145]

Joe, I'm curious about your theory if you feel like sharing it with us.
Mike

He!! why not, we could all use a laugh ;D

I've tumbled em due to carbon buildup. Nothing new there.
I've tumbled or vaporised them due to copper buildup. Nothing new there.
Tumbled em due to a nicked crown. Nothing new there.

Strangest thing I've ever seen a bk do is lose its nylon tip in flight. This one was/is a real puzzler.
35 Bergs have always been the accuracy pill. The BC of the 39bk has always beckoned.
Twas something like the fifth time I tried to utilize the 39bk for competition use. I was on my fourth Sav factory 204R tube. Really wanted them to work this time around.

Accuracy with the 39 is fairly easy. Never quite as precise as the 35 Bergs but close enough considering the BC advantage. Over the course of several days I had been tweaking a load in at 200yds. The bulk of the groups would fit under a nickel @ 200 maybe a dime at times. I always felt I was getting close. The inexplicable fliers kept getting worse.
3" 4" 8" 12" fliers while 85% of the shots were acceptable. A few rds never were found on paper.

One trip to the target I noticed an extra, albeit small hole in the paper. Unmistakeably a keyholed full nylon tip "root" and all. Sure enough just under the paper I found that tip wedged in the face of the plywood backer. Darn thing was almost perfect, just some slight deformation from hitting the plywood. I knew exactly what bullet it belonged to. It was the last shot that flew 4' away from the group. The tip was about 2'' away from that flier.

At that point I stopped load development and started testing. Switched to WS2 to see if that helped. Still got strange flyers. With a linemans plier I could not rip the root of a nylon tip out of a bullet. Obviously I could rip the tip off but the root always stayed behind.

Seeing as I wash my pills in Acetone before applying WS2 I wanted to rule that out even tho it happened with naked pills also. Soaked a few for three days in Acetone. Same results, it seems Acetone will not harm those tips FWIW.

I found one more tip stuck in the target before I stopped testing. That along with the consistent fliers leads me to believe theres more lost tips I never found.

So, my theory is the core seperated from the jacket and pushed forward forcing the hole to open in the front of the bullet allowing the tip to fly free. I see no other explanation how "at least two" tips could come out in perfect condition.
I assume the rest of those huge fliers were missing tips. At 200 yds I feel lucky to actually have captured two on paper. I would assume they needed to disengage mere feet from the target to actually impact it.

Its not hard to conjur up reasons this might happen. Carbon ring, rough bore, copper fouling.
I tried dirty bore and scrubbed clean.

What I never really could grasp is how that tip got out without the bullet tumbling??????
The flier holes were always just as concentric as the others.

Thats my BK story and I'm stickin to it.

 

[Tozguy]

Very interesting...
I'm not familiar with the 204 but those little pills must be spinning like crazy...
If some tips found in the target came away close to the target at 200 and some presumably flew away sooner that you didn't find, have you made any particular observations on targets shot at 100? Sure seems like the jacket is too thin or soft.
If I was Stephen Hawking, I would be calculating the spin rate and the forces acting on the bullet.

 

[jo191145]

Mike

Yes the 39bk is the softest bullet in 204. Varminters love em for the explosiveness.
If your gonna get bullet problems in 20 cal its gonna be a Sierra.
I've fired probably 10,000 + 204R rounds at paper. Never saw a hint of trouble with anything else.
Usually the top node in 204R without getting crazy is 3850/3950fps for the 39. Standard twist of 12.

I've seen them group well down at 3600fps. Never liked the idea of running a 204 at 223 speeds.

Very seldom shoot at 100yds. I need them to work at 300. Its too easy to shoot tight groups at 100 that perform poorly farther out.