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Need help figuring out my grouping problem

 
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  #1  
Old 08-05-2014, 06:32 PM
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Join Date: Apr 2012
Location: Oregon
Posts: 19
Need help figuring out my grouping problem

Just finished building a new STW, im in a huge time crunch for a coveted Oregon antelope hunt in 10 days. I'm having trouble figuring out what the deal is and hoping someone can see something I'm not.

Rig: Remington 700 7mm STW with Pacnor 26" barrel 1:9 twist, Vais brake, McMillan Game scout stock, Jewell trigger, Nightforce NXS 5-22, Nightforce rings and rail.

The best powder/ammo combo is 73gr H4831 with Barnes 168gr LRX

PROBLEM: at 100 yards I can shoot 4 out of 5 rounds 1/2 MOA, but 1 out of 5 is always a flier at least 2 inches off the group. All velocities are close to each other. Barrel is clean each time I shoot a new 5 set. No rhyme or reason on which shot is the flier either.

ATTEMPTED FIXES: different powders(retumbo, h1000, & RL22), charges, bullets, different shooter, different rest, fowled barrel, factory ammo, checked tightness of rings and bases, checked action screws, barrel is bedded and floated, no over-pressure signs.

Am I missing something obvious? I can't seem to shoot a group without having an unexplained flier. I didn't spend the time and money to build this thing to have to worry about a flier. Again I'm in a time crunch to use this thing in 10 days, yes I have other options, but I want to figure this gun out.

Thoughts?
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  #2  
Old 08-06-2014, 07:45 AM
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Join Date: Feb 2012
Location: Ohio
Posts: 95
Re: Need help figuring out my grouping problem

For the cleaning, are you getting all of the copper out?

How was the barrel broke in?

For the loads used, what primer are you using? What other bullets have you tried? Have you tried different bullet seating depths?

For the LRX 168gr, how do they look for the hole on the traget? Are they nice and round or oblonge?

How long do you wait between shots? I usually wait about 1 minute with the one STW, as it has a heavy barrel. For my second STW, I will only do a 3 shot group due to it has a lighter barrel on it.

Do you change the point of contact for the front rest?

How is your breathing when you pull the trigger?

How about the trigger, where is the poundage set?

Just some other things to think about.

Bill
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  #3  
Old 08-06-2014, 09:16 AM
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Join Date: May 2012
Location: N.D.
Posts: 3,016
Re: Need help figuring out my grouping problem

watch your trigger control, bagging, and follow through. If 4 of 5 are coming in it's likely shooter error causing the last to be pulled from the group. If you have the chance, have someone watch to see if your pulled shots show up in the rifle coming off the bags awkwardly, etc.. That has helped me a lot with my rifle. I had a problem with my rifle similar to your problem; I was letting the rifle get jumpy on the bags and she wasn't recoiling straight back every time, but off to the side once on a while. If you are sure it isn't shooting technique, then I'd progress from there.

I'd also check your rifle again from top to bottom to make sure you don't have something just "snug" as it'll also sometimes do what you are describing.

If everything's buttoned up and tight, I'd run a new load run-up with a different primer. Inconsistent ignition causing vel. variation can cause fliers too.

Black67has something too with the 168 being a long bullet-- if they are key-holing one could be diving out arbitrarily and spoiling your group. You'll have to go to a shorter/lighter bullet if that is happening.

I don't think it'd bbl. break in or trigger #... I shoot factory triggers and rifles that are broken in by firing a box and cleaning and they do just fine without fliers.
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  #4  
Old 08-06-2014, 12:51 PM
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Join Date: Apr 2012
Location: Oregon
Posts: 19
Re: Need help figuring out my grouping problem

Quote:
Originally Posted by Black67 View Post
For the cleaning, are you getting all of the copper out?

How was the barrel broke in?

For the loads used, what primer are you using? What other bullets have you tried? Have you tried different bullet seating depths?

For the LRX 168gr, how do they look for the hole on the traget? Are they nice and round or oblonge?

How long do you wait between shots? I usually wait about 1 minute with the one STW, as it has a heavy barrel. For my second STW, I will only do a 3 shot group due to it has a lighter barrel on it.

Do you change the point of contact for the front rest?

How is your breathing when you pull the trigger?

How about the trigger, where is the poundage set?

Just some other things to think about.

Bill
-Break in: I shot 1 and cleaned for 10. Shot 3 and cleaned for the next 30.
-primers: Using CCI mag rifle, going to try Federal mag rifle.
-cleaning: scrubbing with Hoppes 9 then patching 'til clean, then scrubbing with either Hollands witches brew or CR10 and patching 'til clean, 1 patch with alcohol, then an oil patch.
-Other bullets: I've tried 160 Barnes TSX FB & Factory 160 Nosler AB
-Holes: They are ripping the paper slightly, leading me to believe they are key-holing somewhat, the TSX loads were perfect little holes but a crappy group.
-Rest: I am not changing the point of contact and my breathing seems controlled. To rule out human error I even shot off a lead-sled (Im not a fan of them) to assure it was a steady shot, same results. Had my buddy shoot off the bags, same result.
-Trigger: its a Jewell set at a nice crisp 2.5 lbs
-Time between shots: Im not waiting a particular time (prob atleast a min) after I see where I hit, jot down the chrono speed, reload, and find aim point. Its a #4 contour so not heavy, but doesn't seem to get very warm.

A big thing I forgot to mention was, McMillan screwed up the barrel channel of the stock where it wouldn't fit well. My smith had to inlet it some to free it up. Its now bedded and free floated up to 3" in front of the recoil lug. Next time I shoot I'm going to check the free float before each shot.

Thanks for the help so far. Any other thoughts with my answers above?
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  #5  
Old 08-06-2014, 10:44 PM
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Join Date: Feb 2012
Location: Ohio
Posts: 95
Re: Need help figuring out my grouping problem

For you handloads, do you know how much jump you have to the lands?

For the Federals, if you can get the 215 Mag Gold Match, they are the most consisant. They are well liked with the 7mm STW group.

Checking the barrel channel is a good idea. The barrel might also like some light pressure near the end of the forend. I have seen that before.

Bill
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  #6  
Old 08-07-2014, 09:24 AM
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Join Date: Jan 2008
Location: Falls Church, VA
Posts: 3,263
Re: Need help figuring out my grouping problem

This sounds like a bedding issue. Pull your action out of the stock and inspect the bedding. There could be something putting pressure on the action or barrel. Having bedding 3" in front of the recoil lug seem rather far but shouldn't be a problem if the end of the bedding is a clean line and not a jagged edge. When you put the action back in the stock, check to make sure your action screws are torqued properly and that your barrel is floating the way it should.

Alternatively, you could have a bad barrel. I recently rebarreled a rifle and went through everything you're doing. I went to extremes and had someone else load ammo and shoot the rifle. Never could figure out the problem. The resolution was to replace the barrel and magically the rifle shot bugholes after that.
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  #7  
Old 08-07-2014, 11:02 AM
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Join Date: Jul 2011
Location: Pennsylvania
Posts: 1,245
Re: Need help figuring out my grouping problem

Can you post pics of your groups?

Where are your action screws torqued at? 45-65#?

How many rounds down your barrel?

Try cleaning for carbon, not copper.
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