refining groups with ONE outlier

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  • Last Post 01 June 2012
TRKakaCatWhisperer posted this 29 January 2012

For a couple of years I've been working with a rifle that should give outstanding accuracy. Finally I replaced the bolts through the scope mounts and that hold the scope bases to the rail and SHAZAM! 8 five-shot groups that were all very good (first of the 9 groups I was a bit too casual in my shooting) except for ONE %^%# outlier in each group.

That suggests to me the load, as it occured randomly in each string.

OK, I'll go back to shooting groups of 5 slightly above and below this load, and try changing primers (perhaps inconsistant ignition).

I don't have a chronograph.

What else?

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RicinYakima posted this 29 January 2012

Sounds like you are down to weight sorting bullets and orienting bullets to the case and cases to the chamber. Ric

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JetMech posted this 29 January 2012

Sometimes, certain powders will show inconsistant ignition will low charges (position sensitivity), so maybe try lifting the barrel to 45 degrees before each shot and slowly lowering the barrel onto the bags.

A new firing pin spring might help also, along with checking firing pin protrusion. Are you getting a a good dent in the primer?

One last thought, are you full-length sizing? If so, ensure your not setting the shoulder back a hair. If so, you loose some firing pin energy driving the case forward.

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TRKakaCatWhisperer posted this 29 January 2012

Neck sizing only, many-times fired cases. Good thoughts though.

Bullets are very consistant. Hmmm we should have a check-list as a stickey listing all the variables. We've all been down this road before.

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Lefty posted this 29 January 2012

Many-times fired cases triggers a thought for me. I have found that annealing my cases and using enough neck tension to give consistent bullet pull is a must do in order to avoid flyers. Bullets aren't always the problem.

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onondaga posted this 29 January 2012

What else? Consistency of bore condition helps me. Try pulling a Hoppe's bore snake through after every 5 shots, compared to doing that every 1 shot and compared to no cleaning at all. Usually a rifle will like one of those routines very much and reduce fliers.

When stringing loads to find the accuracy sweet-spot, I don't sort bullets by weight until I get groups less than 1 inch at 50 yards. The unsorted bullets will actually help you find the sweet-spot better.

I eliminate neck tension as a variable with sized bullets, The Frankford Arsenal inside neck clean/dry lube brush kit, Lee Collet Die for neck sizing and Then flaring the case mouth before seating bullets with the Lee Universal Expander in calibers that I don't have Lyman “M” dies.

Don't use powders that are position sensitive and I search for the powder that has the lowest pressure and flattest pressure curve for the load area I am hoping to achieve accuracy. For me this is usually H4895, AA5744, in bottle neck rifle cartridges with cast bullets. Straight walled cartridges have a different bag of tricks.

Gary

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CB posted this 29 January 2012

I have a completely different take on the issue of fliers. Maybe I'm just odd.

I think fliers are just the nature of groups. There has to be one shot that you would like to eliminate. We don't like it but unless the flier consistently doubles the size of the group you just have a group problem not a flier problem.

How could one bullet hole out of every five be a result of inconsistencies in bullet weight, defects, neck tension or----? How could it possible happen once in all or even most groups? It doesn't seem reasonable without divine intervention and I think God probably has other things to worry about. Why don't two or three of those assumed bad bullets bunch up in one group and none in the next?

If you were cleaning after every group and the flier was the first or the last shot having one in every group would be understandable. If it was always the fifth shot it might be shooter nerves. Otherwise it would take magic to put one in each group.

It is natural to think what might have been and we do shoot some nice round groups where taking out one shot wouldn't reduce the spread much but they are in the minority.

"Fliers” are the natural order of things for a good share of the groups we shoot. I grind my teeth about that one shot out like everybody else but with rare exceptions it is just how this random world works.

John

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RicinYakima posted this 29 January 2012

If you wish to check for randomness and still insist on 5 shot groups, shoot your groups over one target. That is put a target up, shoot five, put the second target up exactly over #1 and shoot five, take target two down and put up three, again exactly over #1. Keep doing this for at least 5 targets. If the base target has a round group with your “outliers” (odd word), then they are not flyers, but part of the normal group. Another reason not to shoot five shot groups.

Ric

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LWesthoff posted this 29 January 2012

Now we're back to the same “discussion” we had on that recent thread about 3 shot groups - the one that got some of us so - excercised - for want of a better description. You follow Ric's suggestion and you'll learn something worthwhile about your rifle/load/bench technique, but you're NOT shooting five shot groups, you're shooting a 25 shot group.

Shoot enough 3 shot or 5 shot groups, and look at them individually, and you're bound to get one or maybe even two “wallet” groups. Like my old draftsman used to tell me when I came up with an occasional really good solution to some engineering problem, “Even a blind sow will find an acorn once in a while."

However, I don't ever remember shooting a TEN shot “wallet” group. Some of 'em are better than others, but they're all pretty typical of what I, the rifle and the load are capable of.

Wes

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billwnr posted this 29 January 2012

My thought is bedding.

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TRKakaCatWhisperer posted this 30 January 2012

Good thoughts. I'll next get to the range in a week. Will keep y'all informed of the results then. Thanx!

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delmarskid1 posted this 30 January 2012

 If one of us figures this one out and tells the world of it we will have nothing to do but try to prove it wrong. Cast bullet shooting is all about fliers. There have been a lot of good suggestions made here. I have tried most if not all of them. Guess what? I ain't done yet and I love it. Which cartridge do you happen to be working with? Twist? Rifle? Wind? Wobbly shooting bench? It's all about variables and practicing the basics behind the rifle.Keep at it and something will change. Sometimes they get tighter some times they don't. I have a rifle in which I have used very nearly the exact same load at the same range on the fourth weekend of the month for 15 years and the groups change! Figure.

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RicinYakima posted this 30 January 2012

It is always the search for knowledge, not the finding of it, that inspires men.

Ric Bowman, RicinYakima, 2012

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CB posted this 30 January 2012

I like Ric's method of having five shot groups and also ten or 25 or ? shot groups at the same time.

Arguing whether 3, 5, or ten shot groups are better is silly (unless you are naive enough to only look at one group) because it is the total number of shots you shoot that is important, not the number of shots in any one group.

It is equally valid to shoot three ten shot groups, six five shot groups, or ten three shot groups. If you do all three and then compute the average of each type of group and then adjust the three and ten shot group averages to “equivalent” five shot groups with the well known adjustment factors which come from statistics (given in Joe Brennan's book.) You will find that all three methods give the about the same average.

Conversely you can convert the 3 and 5 shot averages to equivalent ten shot groups and find that the 3 and 5 shot averages properly adjusted to ten shot will give about the same equivalent ten shot group size as the average of the actual three shot groups.

The point is that you can get a pretty good indication of how accurate a rifle is by shooting 30 shots. It doesn't make any difference what the size of the individual groups are IF you count all the groups and they are adjusted right.

John

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runfiverun posted this 30 January 2012

random unexplained flyers. either you need to weight sort. or you are getting lube purge. or your lube is coming off the boolits in uneven chunks.

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Ken Campbell Iowa posted this 30 January 2012

onondaga wrote

some lubes and some barrels  are sensitive to time between shots ..i think something to do with barrel conditioning...whatever that covers.

might be interesting to fire a 20 shot group and have someone yell “fire ” about every 30 seconds.

not the same as --warming the barrel -- else it wouldnt happen on 105 degree days ...

some shooter a few years ago wrote  ” flyers keep ruining my groups  ”   (g)

chaos my butt, we gotta blame this on SOMETHING !     ken          

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joeb33050 posted this 30 January 2012

If the question is about how to increase accuracy: It seems to me that there is a progression of steps that one should use in the search for accuracy. With a rifle/load shooting 2” 100 yard groups, weight sorting primers probably isn't the correct next step. After a lot of input I ended up with this hierarchy of steps-from the book.

joe b

see attachment below

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joeb33050 posted this 30 January 2012

If the question is about the group shape and size and flyers: The groups must be “in control", means that each shot in the group must be made from the same gun/load, meanss that there is one distribution of shots. The easiest and least precise method of assessing if the group is “in control” is to see if it is round. How round? How many shots? It ain't easy. We want to separate groups with random outliers, which are part of all groups, from groups with outliers that show that more than one distribution is involved. Outliers are to be expected, but seldom. Frequent outliers mean multiple distributions. What means “frequent"? It is a puzzlement. I think/hope that the answers lie in the groups that we shoot, if we find out how to extract the information. I'm working on it. joe b.

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TRKakaCatWhisperer posted this 30 January 2012

Good suggestions, comments. I've polished the brass. Next to check length, deprime, neck size - etc etc.

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CB posted this 30 January 2012

I have great respect for Joe's work in trying to figure out the best practices for cast bullet shooting and make that knowledge available to anybody interested. His encyclopedic list above for improving accuracy includes about all the possible things you can do that sort of seem like they should improve accuracy. He has stopped short of such things as sprinkling holy water on the muzzle but has included about everything else anybody could think of. To be fair, he has expressed doubt about some of them.

However, the list is too long to provide effective advice to someone trying to reduce his two inch groups. Many of the things on the list if done will waste a lot of time and are highly unlikely to improve accuracy at the two MOA level.

A much shorter list of maybe ten things to check in order of the likelihood that they will improve accuracy would be more helpful. Why don't we collectively see if we can come up with such a list from most likely to help to less likely to improve accuracy? I could start with nominating one thing. Make sure that the CB fits the throat/bore in a way that seals against blowby of gases.

John

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runfiverun posted this 30 January 2012

use the minimum amount of lube necessary, and make sure it either all comes off at the muzzle or stays on all the way to the target. viscosity is the key.

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