Ragged holes vs clean holes

[thane]

Hi guys
Something that I have always wondered about was the holes
that are made in paper targets from various bullets.
While some holes look as though the bullet has sqeezed
through making very clean holes and other holes made
from different bullets will have small tears around the
perimiter.
Hornady bullets for example will most consistantly make
holes that are ragged but yet produce good groups.
The best looking holes I've seen were made from sierra
107 matchking. This makes it very easy too measure from
edge to edge.
My personal feelings on this is that on some bullets the
center of gravity is not on center or it has something to
do with pitch and yaw.
Does anybody have a better understanding of this behavior
of bullets in flight.
Thane

 

[jb77]

Thane,I was experiencing the same thing a few years ago and i switched to a target that is printed on heavier paper and i put a cardboard backer behind my targets. This cleaned the holes right up.

I knew that i was shooting bullets that my rifle would stabilize. But was getting a lot of ripping on the target due to the target not being supported.

If this doesn't work, you may be trying to shoot heavier bullets than the barrel of your rifle will stabilize, or possibly the crown in your barrel may be damaged or not cut squarely.

Good luck.

 

[SF340Driver]

Same here, I use foamboard for a backer for my targets. It's readily available at Walgreens, Target, and Wal-Mart.

 

[thane]

ib77
I understand that differend backers and heavier papers
will give you different results.
All else being equal:
-same actual target and paper
-same distance
-same rifle
-same tongue position
-same brass
-same powder
-DIFFERENT BULLET
I'm just tring to understand better the
relationship between stability and accuracy.

Thane

 

[jb77]

Thane, at what distances are we talking about?
At extreme distances I believe that bullets that are not well balanced could start to yaw or wobble due to velocity decay. But at relatively short ranges I believe the spin imparted to the bullet by the rifling either will or will not stabilize the bullet. If the bullet is unstable you are definitely going to see more of an indication than small tears around the holes on the target.

If the base of the bullet is yawing around the axis of flight then that could impart the tears to the target.Question how many revolutions would the bullet make along it's lenght as it passed through the target?

The Hornaday bullets that you are talking about would not shoot small groups if they were not well balanced. As the spin imparted by the rifling would have an out of balance bullet flying all over the place.

I would suspect that the shape of the holes in the target has more to do with the shape of the bullet, whether the bullet had a cannelure...

 

[BHarvey]

I've seen this myself with 123's in a 260. Even with cardstock mounted on stiff cardboard, at 100 yards, some MV's produced ragged holes, some produced slightly ragged but with more black around the hole, and some produced a very small, very clean hole that had a thick black outline with no tearing of the cardstock. In this MV's range, my rifle produced the tightest groups at 100 and 200 yards. With an 8 twist barrel and MV of 2775 fps, the rpm's were 249,750.

 

[thane]

ib77
The distances we're talking about are 100-150 yds.
these are the ranges that I develop my loads.
I can see that there would not be much spinning
going on as it passes through the paper but none the
less, it still gets my curiousity.
The bullets that typicaly make cleaner holes are match
bullets. Perhaps it could be the small hole in the end
acting as a hole cutter.
You know what, I'm likely making a mountain from a mole
hill out of this.
Thane

 

[thane]

BHarvey
Yes, thats it. Some of my most impressive groups have come
from my 243 barrel shooting the 107 sierra mk bullets.
They always had the clean holes with the black ring.
That thing can shoot 1" groups at 500 yds with those bullets.
My 6br barrel does the same thing with most match bullets
,that is, clean holes with black rings) and also very close to
it with sierra 70gr blz king. The 65 gr. hornady bullets are
very ragged but remain very accurate despite.
Thane

 

[USAPatriot]

Something else to consider is the shockwave that precedes the bullet. I'm no physicist, won't even attempt to try to analyze it, but in my head I can see the difference in how the tiny bit of air between bullet and target reacts on impact, a match hollowpoint vs a ballistic tip, etc. That bit of compressed air likely tears, or begins to tear, the target before the bullet actually touches it. What happens after that, I couldn't say. -Rod-