position of meplat pin hole in bullet holes

[johara1]

I just checked some of mine and they too are a little off center on some. but I would bet it is all due to a bullet hole behind where it enters the target and it moves it off center. you would need a totally new backer without holes and the target tight on the backer. then see if it does it again..... jim

 

[CaptainMal]

Johara1 has the idea. I think it's the paper and the backing. Looked over some 600 yard targets from the match last week. There sure are different meplat angles. I looked at maybe 8 different targets going back to last month and saw some offsets more pronounced than others. Thinking it might be the initial resistance into the backing, coroplast board for mine, If there's a shard of it sticking out, that may cause an initial deflection that could show up. Couple that with a loose paper only pinned in the far corners and it's just possible it's a target hold issue.

Mr%HFawATUmDWGQU0JtClA by Larry Malinoski, on Flickr

 

[Laurie]

Unfortunately, I'm not aware of any easy way to determine what, exactly determines when a bullet will do this. I have seen literature that suggests boat tail angle plays a role, as does the sharpness of the heel.

Bryan Litz addresses that in this section of Vol I - ie the slightly rounded heel. He machined it off a number of 185 Juggernauts and hey presto, the yaw disappears and BC is slightly improved. As he says though, there is at present no way of economically manufacturing BT bullets in bulk in this form.

A return to long-range flat-base bullets in the future, maybe? Increased base-drag but a more stable and consistent performer at long range potentially. There are some such custom designs around, aren't there?

 

[dkhunt14]

I just checked some of mine and they too are a little off center on some. but I would bet it is all due to a bullet hole behind where it enters the target and it moves it off center. you would need a totally new backer without holes and the target tight on the backer. then see if it does it again..... jim

It would be interesting to use a spray adhesive and fasten it to carboard. See if it would disappear or get less. I know I shot some with perfectly centered holes with 240 Sierras, years ago. I know the backer cant lean or it shows up.

Maybe when it hits the ridges of the plastic backer, it deflects them. The plastic we use now has slight ridges. Then again after use they have alot of holes near the center. Matt

 

[Milo 2.0]

I think this occurs whenever you shoot through cardboard or coroplast. Bullet takes the path of least resistance, ribs in the material deflect the bullet some. Just shoot groups at 100 in coroplast alone, groups always appear tighter because the existing hole sucks the subsequent ones in, you'll have one tiny hole but bullet edges are clearly visible going in.

 

[johara1]

It would be interesting to use a spray adhesive and fasten it to carboard. See if it would disappear or get less. I know I shot some with perfectly centered holes with 240 Sierras, years ago. I know the backer cant lean or it shows up.

Maybe when it hits the ridges of the plastic backer, it deflects them. The plastic we use now has slight ridges. Then again after use they have alot of holes near the center. Matt

Matt, I use Corplast at home and if get some shitty looking holes at 100 yds even after you shoot a lot into it. It stretches and it isn't flat any more.... jim

 

[dcali]

Bryan Litz addresses that in this section of Vol I - ie the slightly rounded heel. He machined it off a number of 185 Juggernauts and hey presto, the yaw disappears and BC is slightly improved. As he says though, there is at present no way of economically manufacturing BT bullets in bulk in this form.

A return to long-range flat-base bullets in the future, maybe? Increased base-drag but a more stable and consistent performer at long range potentially. There are some such custom designs around, aren't there?

Short boattails are underrated. The drag penalty for significantly reducing the length of the boattail is small, and can more or less be made up by lengthening the nose. That has its issues as well, but I don't think this is a well traveled area of bullet design simply because its so hard to do, and the effects are not readily apparent until you start shooting long range, which has only been popular for a relatively short time. It's also very hard to explain to the casual rifle enthusiast, which makes marketing difficult.

The easiest nail to hammer down is BC. I think we are going to find out soon (or we already know, but are unwilling to admit) that chasing BC is not the complete answer. I don't think we will see material increases in BC going forward. The effort needs to shift towards making well behaved bullets with as high a BC as is practical. That's my subjective opinion, at least.

 

[dcali]

As he says though, there is at present no way of economically manufacturing BT bullets in bulk in this form.

If people are willing to manually point bullets, I would guess that given a reasonably affordable and foolproof tool, they would be willling to shave a few thous off the base. I bet it could be done if pushed to the handloader to do.

 

[Laurie]

The easiest nail to hammer down is BC. I think we are going to find out soon (or we already know, but are unwilling to admit) that chasing BC is not the complete answer. I don't think we will see material increases in BC going forward. The effort needs to shift towards making well behaved bullets with as high a BC as is practical. That's my subjective opinion, at least.

I agree!

 

[dkhunt14]

The effects are not readily apparent until you start shooting long range, which has only been popular for a relatively short time. It's also very hard to explain to the casual rifle enthusiast, which makes marketing difficult.

Longrange accuracy shooting has been going on for quite awhile. Williamsport 1000 yard BR club has been shooting over 50 years. Matt

 

[Laurie]

If people are willing to manually point bullets, I would guess that given a reasonably affordable and foolproof tool,

 

[Alexander-M]

Honestly, I had never paid attention to this; i.e., meplat location within POI.

I looked at several of my targets (have been keeping them for the past five years), and they all exhibit the characteristic raised by Dave. Below is an example.

Target Details - I print the targets on 8-1/2 x 11, 110 lb paper, which I then tape on to a larger paper that holds up to six of the 8-1/2 x 11 targets. I staple all to the backing, which resembles corrugated plastic.

As you can see from my notes, I shot #1 through #9 with 11-4/8 Up, and then decided to raise the 10th shot by adding 2/8, but it went too far. The three shots in Ø1" orange center were #9, #6, and #2, but the red markings do not show well.
(1XF means that brass case had been shot once before, the powder was H4831SC, 54.80 gr, and the bullets Berger 7mm Hybrid 180 gr. The 4" group noted excludes shot #10))


Just contributing to the topic...

Alex

 

[alinwa]

Honestly, I had never paid attention to this; i.e., meplat location within POI.

I looked at several of my targets (have been keeping them for the past five years), and they all exhibit the characteristic raised by Dave. Below is an example.

Target Details - I print the targets on 8-1/2 x 11, 110 lb paper, which I then tape on to a larger paper that holds up to six of the 8-1/2 x 11 targets. I staple all to the backing, which resembles corrugated plastic.

As you can see from my notes, I shot #1 through #9 with 11-4/8 Up, and then decided to raise the 10th shot by adding 2/8, but it went too far. The three shots in Ø1" orange center were #9, #6, and #2, but the red markings do not show well.
(1XF means that brass case had been shot once before, the powder was H4831SC, 54.80 gr, and the bullets Berger 7mm Hybrid 180 gr. The 4" group noted excludes shot #10))

View attachment 1067477
Just contributing to the topic...

Alex

THANK YOU Alexander-M!

Thank you for showing me I'm Not The Only Blind Guy In The Room LOL!

 

[gunsandgunsmithing]

I've long been under the impression that a bullet will point "into" the wind. Looking at some targets posted, that seems to be somewhat true, but there are several unknown variables, like where was the shooter holding and what was the last wind the bullet saw on its way to the target. I'm not sure how much value any of this has. It may be a lot or nill but it seems what we need are pics of missed wind calls rather than small groups. I still think the last wind the bullet sees it likely the determining factor in all of this but perhaps there is a correlation between bullets pushed out a given direction and where the meplat hole appears. FWIW--Mike

 

[JRS]

This is one of those areas in which I would like the good RG Robinett to give his opinion.

 

[goodi]

for practice purposes on our home range, we place our IBS 600 yard BR targets in a vertical position in which the paper is firmly tensioned but there is no material backing behind the paper.

examination of the bullet holes on these targets highlights the fact, that off centre pin hole locations continue to occurr.

I encourage others to carry out similar testing and then report their findings.

 

[Ned Ludd]

This is an interesting topic and one I've never really payed any attention to prior to this thread. I'd be curious to know whether it is largely independent of distance, or becomes more noticeable as the distance increases. Clearly on the target images posted, there does not seem to be a clear pattern to the direction that the hole is off center.

 

[johara1]

I see that the outside of the bullet hole is rounded the tear hole is off center. If it were off center say .010 the out side circle of the hole would be a lot more due to being a 1.250+ in length. I checked my targets that showed off set in the tear hole and the bullet will not even go in, so no yaw. It is a simple thing on how the paper starts to tear because it isn't supported evenly. I looked a a lot of 2" five shot groups and 4" Ten shot groups at 1000 yds. and it is there also. If they were yawing the wouldn't be that small...... jim

 

[johara1]

This is an interesting topic and one I've never really payed any attention to prior to this thread. I'd be curious to know whether it is largely independent of distance, or becomes more noticeable as the distance increases. Clearly on the target images posted, there does not seem to be a clear pattern to the direction that the hole is off center.

No, a 100, 600 and 1000 all show same thing, it is the backing the target is on I think. I may try no backing to see if it changes the tear hole being off center. With the bullet hole being round it isn't yawing...... jim

 

[Medic505]

Well thanks a bunch. About the time I had this all figured out, something new to worry about, I'm putting my bullets in straight jackets from this point on....

In handcuffs. Cigarette and a blindfold optional.