Damaged bullets and accuracy

[bsekf]

Been reading ....... again!

I think we all agree that damage to the point of a bullet will effect accuracy. Just read where damage to the base may be even more dramatic.

So, I am now carefully chamfering my cases with a VDL tool to avoid a scratch especially with flat base bullets.

Has there been any serious testing using damaged bullets?

I am thinking of the testing done on damaged crowns.

Bill

 

[Twicepop]

The base end is the steering end. I read a test several years back about using pulled bullets against new of the same kind. If I remember these were SS109s pulled from mil-surp ammunition. They exhibited pull marks, some quite severe and were shot against brand new bullets, also SS109s and there was no difference in the accuracy even though some had deep pull marks. They said that all the bullets that had the pull marks, it was along the shank of the bullet and not at the tips or the base. The writer concluded that abnormalities these bullets had was straightened out in the leade and through the barrel.

 

[Rdlningcltchdmpr]

Yes , if there is a ding in the edge of flat base bullet's it will degrade accuracy. I saw the test done 20 year's ago. They also showed at 100 yds that tip damage was not a big deal. Also another test for barrel crown damage was inconclusive. Weird !

 

[garandman]

In theory....

* ANY * damage to any part of a bullet reduces it to a crap shoot. Damage will likely cause the center of gravity of the bullet to be out of spec, and might make it spin erractically.

Down range, the effect is unpredictable. But if accuracy is my goal, and confidence in my equipment / projectiles is essential (and it is) then I'm only ever using "perfect" bullets (or atleast with no known defects) .

I've got $3-4K in my rifle, optics and another $ 1K in reloading equipment, and expended an unrecoverable part of my life span to load quality ammo. Why would I choose to use a known defective $0.20 - 0.40 bullet?

 

[Coyotefurharvester]

If the bullet tip has no bearing on bullet performance, why are there "polymer tipped" bullets. Heat resistant polymer tipped bullets and now aluminum tipped. Each a "proven" accuracy and ballistic advancement.

 

[Fast14riot]

In supersonic flight, trailing edge has more influence than leading edge. I learned this when working on missiles that would change rotational direction as they entered transsonic to sub sonic speeds, letting the leading edge take over. Both edges of the fins were chisel shaped, on the same side.

So, keeping the bullet base clean and perfect is important. Burnishing case mouth chamfer with steel wool can help, too.

 

[Rdlningcltchdmpr]

Wrong ! The test were conclusive. Tip damage shows virtually no difference at 100yds. Base damage shows significant loss of accuracy.

 

[Ggmac]

If the bullet tip has no bearing on bullet performance, why are there "polymer tipped" bullets. Heat resistant polymer tipped bullets and now aluminum tipped. Each a "proven" accuracy and ballistic advancement.

Tip damage will show accuracy degrading in long range after the bullet has reached its highest point in its trajectory , testing at 100 will show base damage ( flat base ) at 100 .

 

[garandman]

All bullet damage is bad. I don't really care at what distance. Or why. lol

 

[_Raining]

If the bullet tip has no bearing on bullet performance, why are there "polymer tipped" bullets. Heat resistant polymer tipped bullets and now aluminum tipped. Each a "proven" accuracy and ballistic advancement.

Higher BC isn't guaranteed to have higher precision.

 

[JRanum]

Frank Mann showed the base is critical 110 yrs ago when he shot a group with good bullets then put a nick in the base of the next 10 and indexed them and shot a circle around the 1st group

I think we all agree that damage to the point of a bullet will effect
accuracy. Just read where damage to the base may be even more dramatic.

So, I am now carefully chamfering my
cases with a VDL tool to avoid a scratch especially with flat base bullets.

Has there been any serious testing using damaged bullets?

I am thinking of the testing done on damaged crowns.

Bill[/QUOTE]

 

[Ares]

If the bullet tip has no bearing on bullet performance, why are there "polymer tipped" bullets. Heat resistant polymer tipped bullets and now aluminum tipped. Each a "proven" accuracy and ballistic advancement.

Aluminum tipped bullets have been around for a very long time.
That Hornady marketing comes up with old ideas as the newsest and greatest does'nt mean it is so.

 

[Jennb]

If the bullet tip has no bearing on bullet performance, why are there "polymer tipped" bullets. Heat resistant polymer tipped bullets and now aluminum tipped. Each a "proven" accuracy and ballistic advancement.

Sales!

 

[Jennb]

Here is a link to an unofficial test that was done with intentionally damaged bullets

https://www.theboxotruth.com/the-box-o-truth-49-damaged-bullet-accuracy-and-the-box-o-truth/

 

[Bart B.]

Tip damage will show accuracy degrading in long range after the bullet has reached its highest point in its trajectory

What changes at about 56% (high point) of target range?

Why not at short or medium ranges?

Isn't the bullet's spin axis is always parallel to its trajectory path?

 

[gme]

I had the opportunity to set with an engineer from a well known powder company for an hour in my office not long ago, one of the topics that came up was the affect of bullet damage, he confirmed that in their testing (short range) tip damage did not have as detrimental affect on accuracy as base damage, at long range where the damaged tip would degrade the bullets BC I'm pretty sure it would be a different story

 

[Coyotefurharvester]

Funny how the box o truth test completely supports the tip and the base of a bullet as being a critical part of accuracy. The intentionally damaged bullets group poorly (except the shaved tips)compared to the control groups(undamaged bullets).

 

[Ggmac]

What changes at about 56% (high point) of target range?

Why not at short or medium ranges?

Isn't the bullet's spin axis is always parallel to its trajectory path?

According to military and some recent books , the g-1, g-7 over stabilized bullets , say a 55 Gr fired in a 7 tw , will stay point up on its downward trajectory. Increasing its surface area and drag .
I don't think it's always 56% . In reality your bullet starts dropping as soon as it leaves the barrel if the barrel is held horizontal, but since our scopes are aprx 1.5" above bore we have to have the bore and POA meet somewhere.
If we pick 100 yds , and hit our target most would not have reached its maximum height above bore ( it would have to have more than the 1.5" drop at that range , back to the 1.5 above bore )
Long range is where the amount of scope height over bore can't be equaled , drop is more than scope height .
Got off track with over spin in first paragraph
Spin axis, when parallel to its trajectory , okay I need to go back Brian's books or the military test , I FORGOT what I was thinking , which may be a good thing
Please explain if I'm wrong ....

 

[davidjoe]

I’ve mangled tips beyond recognition with pliers. Even crunched bullets into the case with a rubber mallet against a concrete bench. All permutations of ridiculous damage you can imagine. At 100, no difference. 200 no difference. 600, sometimes, no difference. Othertimes 1 or 2 moa flyers. It’s eyeopening and revelatory as to 1) the short range game and 2) certain assumptions we have about seating depth and neck tension.

 

[Bart B.]

Ggmac,

All the ballistic software I've used calculating bullet trajectories with typical rifling twists and muzzle velocities have the maximum ordnate in the upper 50's in percent of target range.

308 Win bullets typically have about 1.5 degree trajectory down angles at 1000 yards.

I don't think any bullets are fired fast enough in their highest velocity and typical fastest twists to keep their spin axis always parallel to the line of fire. However, bullets spinning well over 250,000 rpm has balance issues to deal with if they keep a given up angle. If their jacket doesn't split in a groove made by the lands. That happened with Sierra's first 28 caliber 168 grain HPMK bullets shot in 7 Rem Mag 28" 1:9 twist barrels with conventional rifling shapes.