Shooting groups...horizontal stringing.

[CavTrooper76]

So, I know I know Ive read about this before but cant quite find it now, so Im hoping someone here has the answer.

Building a load for my .308, got it shooting allright but I think it can get better. Right now, the widest spread between rounds is happening horizontally, its not outrageous, or even all that bad really, just hoping I can do some tuning and make it better.

Shot today at 200 yards, no wind, off the bench with a rest and rear bag. I didnt have much time so I only shot 3 groups, letting the rifle settle down in between.

1st group was 1.78 horizontal, 1.508 vertical (5 rounds)
2nd was 2.092 horizontal, 2.17 vertical (10 rounds)
3rd was 1.246 horizontal, 1.004 vertical (5 rounds)

Right now, Im fairly pleased with the load since this is the first time ive tried loading for the .308, its still a fairly new rifle (factory Savage 10FP in a HS stock), and Ive decided not to shoot targets under 200 yards unless I have to.

Im thinking about tuning the charge itself a little bit, but Im just curious about horizontal stringing in general. Is it a result of seating depth or something along those lines or is it most likely just the loose nut behind the buttstock?

Thanks for any input you may have!

 

[Winchester 69]

As a broad-brush approach, I would think that horizontal stringing is influenced differently from vertical in two aspects, wind and stock bedding. I would shoot the gun several more times to get a better feeling for wind before I approached bedding.

My next step would be to experiment with the torque of the action screws. If that didn't reveal a source of variation or improvement, I'd consider skim-bedding the mating areas between the stock and action. All of this assumes that you've verified that the barrel is perfectly free-floating.

Canting could also be an influence.
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[CavTrooper76]

As a broad-brush approach, I would think that horizontal stringing is influenced differently from vertical in two aspects, wind and stock bedding....

Canting could also be an influence.

Im fairly confident that the wind played no part this morning, I would lean more towards the bedding aspect as I have yet to bed this gun, canting could be an issue as well. Ive got a new scope mount on the way to replace the one peice deadnutz mount Im running now and will be bedding the rifle and mount at that time.

Im pretty fired up about stretching the legs on this rifle and feeling good about being on or close to a good load. Want to get this new rig dialed in where I feel comfortable pulling the trigger on some furry critters at a distance.

Thanks for the help!

 

[royinidaho]

1st group was 1.78 horizontal, 1.508 vertical (5 rounds)
2nd was 2.092 horizontal, 2.17 vertical (10 rounds)
3rd was 1.246 horizontal, 1.004 vertical (5 rounds)

Hmmmmm,

The difference between Horizontal and Vertical for each group is:
Group 1 0.272"
Group 2 0.078"
Group 3 0.242"

Average group size is 1.706" (extreme spread average) or about 0.853 MOA.

Average excessive horizontal spread average is about .1 MOA or on the order of 11%.

That small of a variance it would be really tough to want to diagnose the rifle.

I'd look at two things:
1) Ensure consistency in anti Cant.
2) Consistent cheek weld.