2 in 1 out grouping question?

[atlatl]

I have read, but do not recall, the approach to a load that consistently groups two shots together and the third out.

For the purpose of discussion, lets assume it is not a rifle issue or a shooter issue. Yes- loose screws, bad bedding, or poor technique are all likely causes of this phenomena- but please, for the sake of this discussion, just focus on the reloading aspect.

Seat bullet deeper? Increase charge? Change powder to faster or slower burn rate? Other tips or thoughts?

Thank you.

 

[stool]

without knowing where your load is and what gun , no idea where to go next.

 

[trailrider121]

Are all your groups 2 and 1?

 

[atlatl]

I am just looking to learn more about load development in a "if this ...then that..." approach rather than haphazardly trying loads until I stumble upon a good one.

I asked specifically about the two in one out grouping because I read somewhere there was an specific remedy for this but I do not recall the answer.

I am fairly certain that the rifle's bedding and my abilities are the two biggest handicaps right now, but I was looking to learn more about refining a load that appears to show promise.

 

[Alex Wheeler]

Adjust seating depth.

 

[Drop Port]

Shoot 5 shot groups and if it continues two grouping bedding and seating depth are most often the cause and cure. If its seating depth there is no way to tell which direction other than try and see what pulls it in.

 

[Brians356]

This points up the problem with using three-shot groups. There are articles out there describing in painful detail the mathematics of sample size and the information contained therein, but one way to look at it is this:

Assume the rifle shoots a 1/2" three-shot group every time - not smaller, not larger - literally 1/2" (CTC) between the two holes farthest apart.

Now, to expect that no two of the holes will be closer together than any other two holes means the three shots must form a perfect equilateral triangle. So you not only get the same size group every time, but you get a perfectly "round" group as well (in that an equilateral triangle's points all lie equidistant apart on the same imaginary circle.)

So the question becomes: What are the chances that two of the holes will not be closer together (i.e. that the triangle will not be perfectly equilateral)? Answer: Overwhelmingly high.

So, it's unreasonable to hope for zero "flyers" from three-shot groups. And it is also nearly impossible to determine the true implication of a "flyer". The so-called flyer may actually be defining the true group size, and the fact the the other two holes happen to be much closer together is simply from chance occurrence - and to be expected.

But this was an academic exercise. Most of us feel we know true flyers when we see them, but that usually depends on having a bunch of other groups on paper from the same batch of ammo which do not show flyers - the group with the flyer needs to be unusual. If all or most of the three-shot groups seem to have a flyer, then I have to question the validity of calling them flyers at all.

Brian

 

[atlatl]

I understand the statistics involved and dispersion from the mean. What I am talking about is a group with 2 (or more) holes touching or nearly so and 1 clearly out of the group (by an amount that would make it statistically UNLIKELY that it was due to random dispersion).

Putting aside the fact that generally a pattern like this would be far more likely due to shooter error, or equipment problems such as the scope, mounts or bedding. I wanted to know what reloading techniques experienced shooters/reloaders try.

Thank you to those who suggested seating depth. Does seating depth primarily affect vertical, so that if the flyer is most often horizontal - is it due to some other cause?

 

[pacificman]

When I get flyers knowing the rifle bedding and scope etc. is all good I will first try different primers then powder and at the very last bullet. I generally always shoot more than a 3 shot group with 5 being the norm. I have always eventually found an answer for the flyers.

 

[Alex Wheeler]

Powder charge generally gives vertical, seating depth can do funny things, horizontal, vertical, fliers (usually vertical or diagonal) but the times I have tuned out "double grouping" it was with seating depth. The times I could not it was the barrel.

 

[Immike]

This isn't the answer you are asking for but I have seen this happen to a few shooters. PACE OF FIRE. Your shooting pace. Shooting fast and relaxed on the first 2 and when they are good then the shooter tenses up and aims longer on the last shot. This is what I have seen several times.

 

[LHSmith]

Assuming one uses wind flags while load testing ....according to my BR notes: Double grouping = a load that is a hair too hot. 5-shot groups would tell you more.
What lmmike said about "choking" on the last shot when there is only one hole is pretty common. The really good competitors have a strategy to minimize the effects of "choking". If interested, it's explained in Jack Neary's tuning seminar on YouTube.

 

[Patch700]

Jack Neary has brought up something along this same scenario except it was regarding a 5 shot group.. 2 distinctive groups ( one group of 2 and then beside it a nice group of 3) the "double group" his theory was not enough powder ... Experience tells us that at longer distances , powder controls the verticle however the above theory is based on short range.

 

[NateHaler]

I have read, but do not recall, the approach to a load that consistently groups two shots together and the third out.

For the purpose of discussion, lets assume it is not a rifle issue or a shooter issue. Yes- loose screws, bad bedding, or poor technique are all likely causes of this phenomena- but please, for the sake of this discussion, just focus on the reloading aspect.

That's like saying "my car conks out, and it might be caused by not enough fuel, but for the sake of this discussion just focus on the battery aspect."

:

 

[243winxb]

Sort brass by 1/10 gr weight after prep. Set shoulder bump to .002" for a bolt action. Get custom neck honed FL die or FL bushing die.

 

[Warren Dean]

"I am fairly certain that the rifle's bedding and my abilities are the two biggest handicaps right now, but I was looking to learn more about refining a load that appears to show promise"

How can you expect to develop a good load if neither you or the rifle are capable..... by your own admission???

"I am just looking to learn more about load development in a "if this ...then that..." approach rather than haphazardly trying loads until I stumble upon a good one."

Try this:

If your technique is suspect, then have someone video you while shooting so you can show the video to someone that knows what good technique looks like and maybe recommend changes. Develop a shot routine that you can mentally run through to verify all the little things are being done correctly each and every shot....that can keep you from choking on that "flier".

If your bedding is suspect, then get it fixed. Lack of confidence in one's equipment is a mental grenade just waiting to go off.

If you do these things, then your ability to refine a good load will be greatly enhanced.

Does that work?

Cheers!
Warren

 

[Mega]

+1 and many more.

I have never and will not believe that firing three shots achieves anything unless you are perfect behind the Butt.

Experience can tell you that one of the shots is off before you even look at the target and know it's not going to be where you expect. That's not an equipment failure it's a mental / training problem.

Have been working with a mate for some years and he could pull a beautiful 4 shot group then everytime the fifth would spoil it.... Mental training and practise so now he gets them all on target and is much happier with himself. He can now put three shots where he wants them and happy that is all required to save barrel wear during testing.

 

[atlatl]

"I am fairly certain that the rifle's bedding and my abilities are the two biggest handicaps right now, but I was looking to learn more about refining a load that appears to show promise"

How can you expect to develop a good load if neither you or the rifle are capable..... by your own admission???

"I am just looking to learn more about load development in a "if this ...then that..." approach rather than haphazardly trying loads until I stumble upon a good one."

Try this:

If your technique is suspect, then have someone video you while shooting so you can show the video to someone that knows what good technique looks like and maybe recommend changes. Develop a shot routine that you can mentally run through to verify all the little things are being done correctly each and every shot....that can keep you from choking on that "flier".

If your bedding is suspect, then get it fixed. Lack of confidence in one's equipment is a mental grenade just waiting to go off.

If you do these things, then your ability to refine a good load will be greatly enhanced.

Does that work?

Cheers!
Warren

Perhaps I believe that self deprication is better than overstating one's abilities. I know that I have room to improve my abilities as a shooter, but I was specifically looking for information on tuning a load. I am familiar with proper bedding, paralax, wind, etc. I asked a specific narrow question to avoid having the thread cover too much superficially rather than one thing in depth.

I agree that three shot groups are not as informative as 5 shot or 10 shot, I was just trying to illustrate a group (of any number) with a satisfactory main group with fliers that are not called by the shooter or due to wind.

 

[cncmill]

I had this happen to me once. The barrel was touching the stock in one place and not free floated. I know it isn't a reloading cause but thought it was worth mentioning. I would then check seating depth.

Erick Crouthamel

 

[XTR]

The point you are choosing to ignoring is the statistics, which is the most likely reason that you will get your dispersion.

If you are having flyers that are way out of the group it's probably the shooter. Three shot groups really tell nothing. Shoot a series of 5 shot groups and find out what the rifle/load/shooter are capable of and then talk. If you really want good statistics shoot 7 shot groups. I think if you run a T test or a WR sum test you'll find that is about your minimum to get a valid statistical group. I think if you use distance from center of the group as the data point value you can make it work. (I've nver run the tests on groups but if memory serves I think that will work)

The reality is that what you are talking about is purely the statistical dispersion of the shots w/i the precision of the system if you ahve eliminated the other variables. If you have not eliminated the other variables (torque screws, barrel pressure points, loose scope etc..) then you are wasting your time.