Group shapes.. what does it mean.

[johnmventers398]

Good morning folks.

I was out doing load development for my 243 win yesterday and really do not know what to make of my results.

I shot 7 groups and all bar one where hovering around .5 inch at 100 yards. The one that was not was just shy of an inch and I pulled/ rushed it.

So, the first group was a beautiful triangle shape which then turned onto horizontal and then back to a cluster.



But anyone have any ideas as to cause or solutions?

As it stands I am at a loss as to which is worth following up and fidiling with.

I will post a photo after work.

John.

 

[Raythemanroe]

Pictures, post some pictures.. You are looking for a pattern that prints at the same point to the bullseye.. Small isn't always the decision factor, if you have a small group but just before that and after it doesn't print in the same area you have most likely a scatter node and the change in weather and environment will screw with your results day to day..

Ladder tests are good for finding the sweet spot..

Ray

 

[JASmith]

The wind can cause some of that.

I thought that wind directly in line with the shooting lane would not particularly affect accuracy, so had trouble working out the cause of my vertical strings. The wind was consistent with what one could expect for horizontal drift with wind strength.

The rest of the story — Our covered benches apparently coased a vortex that caused the bullet to be deflected downward.

 

[johnmventers398]

I was shooting in the field wind in my face.

Pictures added.

The middle group is the pulled or rushed one.

I know they are only 3 shot groups but I am trying to be economic with components.

 

[mike06]

What powder are you using?

 

[chkunz]

These look like three shot groups. You are dealing with statistics. Combine all the three shot groups into one group and that is your group. Mother Nature is a bitch.

 

[johnmventers398]

What powder are you using?

H414 49.4-50.6 gr cartridge base to bullet tip 2.3"

 

[mike06]

Measure your bullets they will vary in length. Try seating base to ogive. About powders I have had the vertical strings also mostly with ball type powders never use them anymore only stick type.

 

[johnmventers398]

Measure your bullets they will vary in length. Try seating base to ogive. About powders I have had the vertical strings also mostly with ball type powders never use them anymore only stick type.

Yeah I know they will. I've not got a ojive comparitor.
I could get my Smith to make one for nothing but he is fairly busy at the moment with other jobs.

 

[johnmventers398]

These look like three shot groups. You are dealing with statistics. Combine all the three shot groups into one group and that is your group. Mother Nature is a bitch.

They are. I was trying to be fickle with components. The average is .6 including the pulled shot.
I'm not sure I understand your comment though. This covers a grains worth in charge variation.

 

[mike06]

There are so many variables that come to play when shooting for groups. I would say you are pretty close in what you are doing. Getting everything the same is the tuff part. Bullet Weight,powder charge,case volume, neck tension just to name a few. Recently I have concentrated on case neck tension, powder charge, bullet weight and seating depth. And don't forget the human factor.

 

[chkunz]

They are. I was trying to be fickle with components. The average is .6 including the pulled shot.
I'm not sure I understand your comment though. This covers a grains worth in charge variation.

I did not read carefully, since you made the powder change you can not combine them as I recommended. But I will say you have to consider the limitations of a three shot group. Once you choose a load, shoot three ten shot groups, preferably on different days, and combine them and you will have a good idea of what you have.

 

[johnmventers398]

There are so many variables that come to play when shooting for groups. I would say you are pretty close in what you are doing. Getting everything the same is the tuff part. Bullet Weight,powder charge,case volume, neck tension just to name a few. Recently I have concentrated on case neck tension, powder charge, bullet weight and seating depth. And don't forget the human factor.

I did not read carefully, since you made the powder change you can not combine them as I recommended. But I will say you have to consider the limitations of a three shot group. Once you choose a load, shoot three ten shot groups, preferably on different days, and combine them and you will have a good idea of what you have.

Ok I'll give that a try. Thanks. Out of the group's on the target which, in your opinion should I focus more effort on? Or do you reckon keep on going till I see pressure or an unmistakable good shooting load?

There is still a fair amount of room in the case. In my experience with this rifle, with heavy bullets.. a light compression load has always shot best.

 

[Bc'z]

Charge weight in between targets 4 & 5
Go to seating depth.

 

[chkunz]

Out of the group's on the target which, in your opinion should I focus more effort on?

I do not have any faith in three shot groups, it is all statistics. You can learn something from a bad three shot group but a good three shot group does not tell you much. But you will see a lot of decisions made that put a lot of faith in them and a lot of people use them. Best wishes, Clyde

 

[johnmventers398]

Than

I do not have any faith in three shot groups, it is all statistics. You can learn something from a bad three shot group but a good three shot group does not tell you much. But you will see a lot of decisions made that put a lot of faith in them and a lot of people use them. Best wishes, Clyde

Thanks

 

[johnmventers398]

Charge weight in between targets 4 & 5
Go to seating depth.

.

Ok thanks. What is the reason for your suggestion?

 

[Bc'z]

Horizontal point of impact between groups on target board. Pick charge weight in the middle to allow for wiggle room in charge variations and temps.

 

[johnmventers398]

Ok thanks. I will explore that area.

Horizontal point of impact between groups on target board. Pick charge weight in the middle to allow for wiggle room in charge variations and temps.

 

[Paddyd]

3 shot groups usually work as well as 5 for me when looking for an accurate load to start tweaking . The reason most groups tend to open with 5 shots are from the shooter rushing them and not relaxing and taking the time to be consistent from shot to shot. As for variables such as ojives, neck tension, powder charge variances, etc, if small, these don't manifest themselves to be corrected at 100 yd ranges. Stretch it out to 200 -300 if possible and see if your minute of angles stay close to the same. Small variances in powder charges will start affecting accuracy as ranges increase. I can use a Lee dipper to dip powder in my 308 and get 1/2 inch groups at 100 yds all day, but when the range is extended to 200, they open up significantly from the variances in charge weights. If I carefully weigh the powder my groups stay consistent as range increases ( within my eye capability) After a certain distance loads don't matter for me because I can't see the target clearly enough to aim at the exact point each shot.
I have found that brass prep needs to be the same for a load to repeat. Everything from annealing to carbon in necks vs squeaky clean can drastically effect bullet tension.
Vertical strings usually mean velocity swings. Horzontal, with windage removed from the equation often means as the barrel heats it is making contact somewhere along the channel in the stock. Then there's the action screws.. It's not always about the load.
In short this is a very deep rabbit hole you and all of us have been down.