Possible Causes of Horizontal Stringing

[Gutshot]

I’m having trouble getting my new Sako 85 to shooting good groups. I’ve been shooting 180 gr Federal Powershock for a few weeks while breaking in the barrel and the best 100 yard group so far has been just under 3 inches. I haven’t been too worried about it because powershock isn’t exactly precision ammunition and I’ve just been getting used to the rifle. This past Saturday I went to a friend’s farm to see how well I could get this rifle to shoot and came away scratching my head.

The vertical alignment was pretty good with groups ranging anywhere from 1” down to ½”. The problem was with the horizontal grouping. Every second shot would stray to the right. A four shot group, for example, would start with one in the center of the target followed by another shot 2.5 or 3 inches to the right. The third shot would be grouped in the bullseye along with the first shot and the fourth shot would stray right again…

These results were consistent and reproducible by both myself and my shooting partner.

Equipment:
Rifle: Sako 85 .300 WSM
Scope: Leupold VX II 3-9X40
Rings: Leupold Ringmounts (low)
Ammunition: Winchester Extreme Elite (XP3) 180 gr (and some hand loads I’ve been working up)

Range conditions: Sunny with wind gusting to 15 km/hr.

We shot prone, with the wind at our backs, using sand bags (front and rear) and waited between shots for the wind to die down.

I’ve gone over all the obvious things like making sure the action and scope screws were snugged up (they were). The scope is level and the rings have been lapped. I’m completely stumped! I’m considering new rings and bases for the rifle – thought I might need something a little more stout for a magnum cartridge but wanted to ask for help here before investing in Optilocks.

Does anyone have any ideas what might be causing my horizontal stringing issue?

[6.5 shooter]

Bedding was my first thought but I am leaning more towards the parallax or how you position your head behind the rifle.

If your scope picture is not the same it maybe placing the rounds to one side or the other? just a thought.

[Dean2]

Horizontal stringing is usually casued by grip pressure or not squeezing consistently. Since hte gun does it for both you and your partner, and the pattern is very repeateable, this is not likey the cause.

Parralax is a good thing to look at, but what makes me suspicious is the 1 and 3 and 2nd and 4th shots grouping togehter. If it was head positon I would think it would be a little more random.

I think 6.5s first inclination around bedding is where I would be looking first. Is the barrel touching, and if not when cold does it when hot. You said you were using sand bags front and rear so am assuming no bipod on the front swivel. If the bag is far enough out on hte forearm you could be getting flex. Try moving the front bag to as close to the front action screw as you can get it and see if the cures the problem.

If not these two, I would look for wear or movement spots in hte bedding nad on the action. I would also ensure recoil lug is perfectly square, inletted so it only touches at the back, not sides or front. I would also Devcon bed from the rear of the magazine to 2" past the rcoil lug, just for good measure.

Good luck and let us know what you figure out.

[jim-bo]

I think that forearm flex and bedding are the first spots to check.

A friend of mine purchased a Browning X-bolt, which would have incosistent strings and groups. It wasn't until he was back in NZ, that a gunsmith informed him that his chamber was cut slightly off bore (and incredibly small amount). He couldn't even tell from his brass.

Funny thing was, it was an accurate gun, especially by my definition. It was only that its groups were somewhat inconsistent and would walk.

I am definitely not saying that this is your problem, but maybe a visit with a gunsmith may help.

[elkhunter11]

I would also suspect bedding. The barreled action may be moving around horizintally in the stock.

[catnthehat]

If every second or third shot was to the right consistantly and you are a right handed shooter, I would agree Dean2 for trigger hand pressure/ trigger pressure.
it is a sure indicator of inconsistant hand pressure .....
Cat

[Gutshot]

Thanks for the feedback fellas. To address some of your points:

• No bi-pod
• Front sandbag was directly under the scope
• Cat you’re correct, I’m right handed.
• I turned down my trigger weight when I bought the rifle but I don’t know exactly what it’s currently set at as I don’t have any way to measure it. I’m guessing it’s someplace between 3 and 5 lbs. All I know it’s not as light as my .308 which is 3 lbs. Could be that the trigger pull is just heavy enough to be throwing off my shots.
• Barrel is free-floating but I haven't checked it warm - will do that next session.
• I used to use the grip of death when shooting to compensate for recoil but my shooting partner showed me the error of my ways and now I’m only using enough pressure to keep the rifle up against my shoulder while I’m squeezing the trigger. Could be that I’m still not entirely consistent with my form yet.
• I also wouldn’t count out inconsistencies with my eye alignment as my scope seems a little high and I’m constantly searching for a comfortable cheek weld that gives me a good/consistent sight picture.

When I bought the rifle I stripped it down and found lots of grease between the action and the stock. I wiped most of that up before I reinstalled the stock. Wonder if the grease was supposed to stay there or if maybe I messed up realigning the action with the recoil lug… I’ll have another look at that again tonight.

At first I was thinking this might be some obscure scope or ring related issue. Hopefully it’s just my form as I don’t want to glass bed this rifle – bought a Sako because I thought they were supposed to be shooters out of the box. Guess nothing in life is certain except death and taxes.

I’m still toying at the idea of getting lower rings for my scope - that will make it easier to find a consistent sight picture without a lot of head adjustment.

I’ll be back at the range this Friday – I’ll let you know how it goes.

[Robmcleod82]

Did you torque your action screws to factory specs?

[silver]

I had something similar on a rifle once. If you shot in a normal time the groups would string horizontally. If you took several minutes between shots, the group tightened up to 1/2 inch. I suspect there was a bend in the barrel. Good luck.

[Bushrat]

Are your Leupold mounts windage adjustable on the rear mount. Seen many rifles with those mounts having the windage screw seemingly tight but not tight enough, they will double group or string shots horizontally. Make double sure that windage screw is tight.

[Robmcleod82]

Originally Posted by Bushrat

Are your Leupold mounts windage adjustable on the rear mount. Seen many rifles with those mounts having the windage screw seemingly tight but not tight enough, they will double group or string shots horizontally. Make double sure that windage screw is tight.

Agreed, If you dont have an inch pounds torque wrench you should get one and use it, you will be suprised how tight 21 inch pounds actually is.

[Gutshot]

Originally Posted by Robmcleod82

Did you torque your action screws to factory specs?

I'm not positive but I'm pretty sure I torqued the action screws to 50 or 60 in/lbs - does that sound about right for a Sako 85?

[Gutshot]

Originally Posted by Bushrat

Are your Leupold mounts windage adjustable on the rear mount. Seen many rifles with those mounts having the windage screw seemingly tight but not tight enough, they will double group or string shots horizontally. Make double sure that windage screw is tight.

Actually I'm using Leupold ringmounts which are bases and rings together so there's no windage adjustment on the rear base. I've read lots of differing opinions about these rings and I think they might work for some setups but I'm starting to question how well they hold on the Sako dovetail for a magnum cartridge. I have no scientific data - just a gut feeling.

[Robmcleod82]

front 50 in/lbs rear 40 in/lbs is what i could find

[Gutshot]

Are those Sako specific settings or just general action screw torque specs? I don't even know that it matters but I'm just curious.

[Robmcleod82]

just what i was seeing with a google search but sounds reasonable, Icouldnt find any specs on the sako web site

[wind drift]

Just because it's easy, have someone else you know to be a good bench shooter give it a go on a different setup (eg. Seated at a bench, softer rest, etc.).

[MK2750]

http://www.outdoorsmenforum.ca/showt...sako+finnlight

[densa44]

If it won't group, and you have my sympathies for trying, why not get a bigger gun that kicks harder, then if it patterns the same way we can surmise that it is your body trying to tell you something. What happens when an empty cartridge is secretly placed in the chamber? Does the rifle jump?

Good luck with this, as I've aged, I'm not getting smarter as I hoped but maybe more cautious, I use a 243 and a 223 to target shoot, and that's enough for me.

[Gutshot]

Originally Posted by densa44

If it won't group, and you have my sympathies for trying, why not get a bigger gun that kicks harder, then if it patterns the same way we can surmise that it is your body trying to tell you something. What happens when an empty cartridge is secretly placed in the chamber? Does the rifle jump?

Good luck with this, as I've aged, I'm not getting smarter as I hoped but maybe more cautious, I use a 243 and a 223 to target shoot, and that's enough for me.

Bought this calibre as an elk rifle, not a target rifle but I expect it to shoot when I need it too. I'll be draw priority 9 for bull elk in two years and when that time comes I want to be confident that if (when) the bull of my dreams walks out at 300 yards I'll be ready to make the shot and my rifle will be capable of performing to my expectations.

I've participated in long range competitions out to 900m so I know how to make a shot and recoil isn't a problem. My target rifle is a .308. I shoot all my rifles weekly using snap caps to practice my trigger squeeze and shooting form. I begin all my shooting sessions with a snap-cap and I do not have a flinch.

[PoppaW]

Elephant gun. LOL. Sounds like a pressure point giving inconsistent pressure

[SkytopBrewster]

When a group strings horizontally but are small over the vertical measurement, you can assume the barrel is being influenced by contact with the stock on either one side or the other. Fold a dollar bill in half and slide it down between the bbl and stock and see how far it goes, is this a wood or synthetic stock?

[Gutshot]

Originally Posted by SkytopBrewster

When a group strings horizontally but are small over the vertical measurement, you can assume the barrel is being influenced by contact with the stock on either one side or the other. Fold a dollar bill in half and slide it down between the bbl and stock and see how far it goes, is this a wood or synthetic stock?

It's a synthetic stainless model 85. Seems like there's lots of gap between the fore end of the stock and the barrel but I'll check it out this evening and get back to you.

[Gutshot]

Originally Posted by MK2750

http://www.outdoorsmenforum.ca/showt...sako+finnlight

Thanks for the link to your thread – a very interesting read.

I took my stock off the action last night and definitely noticed movement between the action and the two pieces. When I reattached the action I made sure to push the action as far back into the stock as possible before torqueing the action bolts. I’ve never bedded an action before but it would be worth the effort if I can’t get this rifle to shoot moa or better but to be honest I'm hoping it won't be necessary.

[densa44]

My barber shoots the same caliber and he has complained mightly about the quality of the ammo that Remington sells. You say you make some of your own. Do you have good groups with the 308? If so, I'd say that if is uneven pressure on the barrel. I guess it is not that obvious or so far at least easy to fix.

[Gutshot]

I checked the gap between the barrel and stock last night - used a paper bill($). The gap seems fine - the paper slid effortlessly all the way past the chamber to the action. Think it's safe to say that's not the issue.

I think this gun can shoot, it's most likely me but if I can't get a decent group at the range tomorrow I'm going to pick up a bedding kit and a new set of rings.

My wife is going to be sooo happy with me

[MK2750]

I am not sure if the stock is of similar design but mine had two oval holes behind the bedding block on either side. They were trying to save wieght but with a flat head screw driver in front of the block I was getting flex at these points.

If you want to keep it simple, remove the block and make certain there is no oily residue. Bed the block in place and fill any holes in that area. I would also do around the rear of the action around the back srew. A tablespoon is all you would need.

I put one piece Optilok rings/bases on mine but they are as rare as hens teeth to find.

If you want to really get the wife worked up put a Swarvo on top instead of that VX2 and drop it in a McMillan Edge.

Rifle is a thing of beauty and it has been so peaceful with the wife not speaking- like a win win

[densa44]

We are down to 2 options I guess the ammo and you. My barber thinks that the ammo is very poor, he has even complained to the manufacturer. He is starting to reload.

Are all the cold barrel shots in the bull?

[catnthehat]

Personally , I'd still try to find someone who can shoot magnums accurately to try it first before doing a bunch of work to it.
I have seen this numerous times where people go to the equipment first then find out it was not that at all.

Cat

[elkhunter11]

The Leupold Ringmounts are plenty strong if they are installed properly. If the bedding area is clean and dry, and the action screws are torqued properly, I would let a proven shooter try the gun, before doing any work on the gun.