The Dreaded Flyer

[rrojohnso]

Hey Guys -

I have tuned up several rounds for my .308. The problem is I inevitably end up with a really tight group (4 shot group 1/4 MOA) but get one flyer that takes my group out to about an inch. Now I suppose it could be me, but it's very consistent to have one flyer out of every shot group. I am thinking the cause of the problem could be neck tension?

Common denominators I've check out and addressed: all flash holes are deburred, All cases are same make and model w/ same amount of firinings, all cases are the same length, primers were the same, powder was measured exactly the same (charge-master scale), bullets are the same weight (by scale), and COL is identical. Barrel is fouled with a few sighters before load testing begins.

Any thoughts? If it is neck tension, how do you guys try and get the most consistent amount of neck tension while working the brass?

Dies: Lee
Rifle: .308 on a Rem 700 action

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[Certaindeaf]

In what sequence does the flyer happen? Is it always the fifth? If it's always the last one.. your barrel got too hot. Is your barrel free-floated or what?

 

[rrojohnso]

Stock is glass bedded, barrel is fully free floating. Barrel is 26" match from Pacnor. It's really heavy, takes forever to heat up and cool down. I try and rest the barrel between strings, and rarely shoot it faster than a round every 2 minutes or so - it's a hunting rifle that's been accurized, and the stock makes it look like a total sleeper.

In my last two strings, the flyer occurred on shot 3 of 5, and 4 of 5 respectively.
When I started to notice the problem, I thought it was me, so I took more time, slowed down my shots, let my barrel cool more between strings, and really focused. That's what makes me think it's a tension issue in the case neck... but I am not sure. I was shooting in the English Pit, and there was little or no wind. flyer in the first string was 10 o'clock 3/4 of an inch out, flyer on the second string was 12 o'clock, also 3/4 inch out (or so).

 

[Morpheus]

If you said you tried this, I missed it but have you put it on a sled to ensure it isn't you putting something odd into the mix? Sometimes the human is the problem, sometimes it isn't. At least this way you will know if you are doing something, or it is mechanical.

 

[rrojohnso]

I haven't put it on a sled yet. I will do that the next time I go. It's really frustrating!

 

[deadshot2]

A tip passed on by a top BR shooter was to take that case that fired the flyer and set it aside.

In his case he would go and reload that same case immediately and shoot it again with the same setup. If it shot out of the main group it went in his recycle bin.

If you're not loading at the range just put that case in a separate box. His feeling is that all cases are not created equally even if they do weigh the same and are nice and true when checked on a run-out gauge.

I've used my own form of his method where I just move that case to the end of my ammo box. Eventually I have 5-10 of them in a group of their own. I do have less "fliers" now but often the groups move around on the target, hitting different POI's from the "good batch".

 

[Certaindeaf]

Valid point. Harry M. Pope, the barrel maker, used one case like what, 40,000 shots? Then he broke in a new one.

 

[P7M13]

Damn good advice Deadshot. Thanks for passing it along.

Here are some good articles about neck tension and runout.

Neck Turning Basics
<broken link removed>

 

[rrojohnso]

Thanks for all your help guys. I haven't pulled those cases aside, but should have - common sense. The links are also very informative.

 

[2506]

I'd go with what Morpheus said first. Nine times out of ten, accuracy problems for me come from the loose screw behind the trigger.