Effects of Transition Speed

462

California's Central Coast Amid The Insanity
A detonation type has a 270° sphere at x ftlb non directional impact firing arrangement . After firing it is 360°² so the shell can hit in any attitude and as long as X ftlb of impact force is present .....poof .

Thanks, RB, that answers my question.
I only dealt with impact type bomb fuzes, and a bomb's fins (other than non-finned, tumbling napalm) cause them to impact fuze down.
 

Snakeoil

Well-Known Member
Keep in mind that all 4 test loads were well over mach 1 at 100 yds.

I am familiar with that Bc vs vel chart and it was one of the input reasons for this particular adventure.
 

popper

Well-Known Member
High BC keeps the projectile super longer. Difference between the trajectory and bullet axis of fig 3 increases and is the main cause of turbulence.
 

Snakeoil

Well-Known Member
Man I thought this would be right up fiver's and Ian's alley!
It is... or was. They both chimed on 2 years ago when I started this thread. Go back to the beginning.

I think Popper had a brain fart when he replied to this old thread. It's happened to me, too.
 
Last edited:

Rick H

Well-Known Member
Okay, where does "putting a bullet to sleep" belong in here? Or does it at all. I have heard that some bullets take time (distance) to stabilize or go to "sleep". Typically, the conversation revolves around boat tail jacketed bullets.
I have observed loads that group as well or slightly better at 200 yds than at 100. They also outperform in terms of MOA at 300 than 100yds. My 1:9" twist 6mm Rem. with 100gr BTSP's will print 1" 5 shot groups at 100 yds. and 1-1.5" at 200 yds. It will shoot under 3" at 300 yds. (given reasonably calm conditions, would love to test in a windless tunnel) There is a smaller number of groups at the longer distances. Some have explained this by stating it takes time for the bullet to settle down.

I can't seem to wrap my simple mind around this one. I can see that the rifle is shooting smaller MOA groups at the longer distances, but that seems counter intuitive. A difference in rotational axis while in the bore than in the air? Why with boat-tails? How does a bullet become more stable the further downrange it travels? I don't think it can! Yet, I can demonstrate the results.

Practically it makes no difference, it is a hunting rifle and much more accurate than I can shoot under field conditions.

Oh!.....and none of this has to do with transonic cast loads. These gems start at better than 3000fps. and stay supersonic well beyond 500 yds. Damn!
 

RicinYakima

High Steppes of Eastern Washington
The best theory I have heard is that the marks of the lands act like the seams of a base ball, throwing a slider. When the bullet exits the muzzle, the air resistence on the side of the bullets wants to push it sideways a little. However, the rotating mass wants to be stable. It takes a distance for things to balance out, air pressure on the side of the bullet and bullet rotation.

That is the best explanation that makes sense to me.
 

Georgia Boy

New Member
You do not need high speed cameras. I have seen this several times on commercial jets. They are pushing close to Mach 1 at 35 to 40,000 feet.The air going around the wing goes supersonic. When the sun is right you can see the shadows of the shock waves dance around on the surface of the wing.
 

CZ93X62

Official forum enigma
Rick H brings up a phenomenon that I have seen with frequency over the years using Sierra Matchking bullets--radial downrange distribution decreasing slightly (MOA) as range elongates. I have no idea why this occurs, but I have seen it enough to know right to the ground that it occurs with my loads in my rifles. A conservative estimate of my use of .308" x 168 grain Matchking is 2500+, and a like number of the .224" flavors in 52 and 69 grain weights in 1-14" and 1-12" twists with the 52s and 1-9" and 1-8" twists with the 69s.
 

RicinYakima

High Steppes of Eastern Washington
The "going to sleep" phenomenon has been reported for over 100 years. We have theories, but no science of exactly why it happens.

Dr. Harold Vaughn, designer of the outside form of nuclear bombs, designed around empirical results but could not explain it from data.