sako 75 accuracy problem

Longranger · 01-10-2015 9:27am #1

Hi all, just asking a question on behalf of a friend as I have no experience of the sako 75. A mate of mine recently bought one in 30-06 and is having real trouble with accuracy. Groups are all over the target. He's tried federal fusion and hornady superformance both in 180 grain, and same result with both. The lad keeps his firearms immaculate and this is the first time I've seen him stumped. I used to shoot a sako 85 in 22-250 and you could literally drive nails with it, and I know a couple of lads who prefer the 75 to the 85. I've looked at the gun and all seems in order, the barrel is spotless. Has anyone had a similar issue, any help would really be great. Thanks all.
LR

German pointer · 01-10-2015 10:06am

I had an accuracy problem with my new rifel recently done my head in tried every brand of ammo and they were all over the place it turned out I never tightened the scope rail properly and I was kicking myself when I discovered the problem now its perfect 1" at 100 yards with PPU . some times it's the simple things a person overlooks

Cass · 01-10-2015 10:51am

Common causes include:

Scope - Self explanatory really. A faulty scope will "jump" with each shot, not track, etc.
Mounts/Rings/Rail - If they are not tight enough, misaligned, etc. they can cause issues with zeroing.
Ammo - Depending on twist rate and what your gun likes poor quality or just a "bad fit" ammo will cause zeroing issues. Solution is to try various brands/weights and see which works.
Suppressor - If the threading of the rifle is not done properly, or on the rare occasion the threading of the Mod is not correct, you will get a misaligned suppressor causing the ammo to clip the mod on leaving. This clipping can be so subtle you might not see it. A way to test is line the inside of the muzzle of the mod with tip-ex or something similar and when you fire a round check to see if there is mark or void in the tip-ex (or whatever you've used). If so you can try and bore out the mod or get the rifle re-threaded.
Stock - If the stock is touching the barreled action it can interfere with the barrel harmonics.
Crown - If the crown is damaged it will cause widening of the groups. It's a small area and unless you know what you're looking for you might not see a problem. Gunsmith can check and re-crown if necessary.

There are some things you can do to check the above.

Scope - If you had it on another rifle and it worked then grand, however a hmr is a different animal to a Swift so try the scope on another centrefire rifle. A mate's. Also a box test might be useful when on the other rifle.
Mounts/Rings/Rail - Check that the screws on all of them are tight and that they are not shifting either by hand or under fire. Also check the scope is held in the mounts and not slipping in the rings. Check the rail is tightly secured to the receiver. DO NOT assume it's tight, take the scope, rings, mounts, rail off and refit.
Ammo - Try different brands, and different weights of ammo. See which performs the best.
Suppressor - Shoot the rifle with the mod off and see if the problem persists. If so the mod is the issue. If not then it's not the mod. Or not ONLY the mod. Bring to gunsmith to check/repair.
Stock - Slide a piece of folded paper up along the top of stock/bottom of barrel and it should be able to get to the front of the receiver/action without obstruction. If it sticks at any point then mark the stock and look at sanding the stock. If it's composite the same applies.
Crown - Bring to gunsmith.

I had a similar issue with a 30-06 (small world). After dozens of shots i was lost. I took the scope off, then went to take the rings off. When i did the front ring was tight, but the back ring was very loose. When the scope was mounted it all seemed tight, but each time i fired the recoil made the scope/rings shift a small amount. IOW each shot was in effect a new "zero" shot.

This is why i say take everything apart and rebuild it. Assume everything is wrong until you can prove it's not.

clivej · 01-10-2015 11:30am

^^^^^^What Cass has said.^^^^^^^

If the rifle is clean then it can only be the scope is broken, Scope rings need tightening, mounts are loose, rail is loose.

I've seen the screw that holds down the ring into the tapered dovetail mount work loose and the ring move upwards. A lad was chasing the POI for ages until he found the problem.

If the crown is still dirty then look at the 'Star' pattern of the residual carbon on it. It should be perfectly symmetrical. Each leg is one barrel grove and they should all be the same shape and length.

Remember you are looking to find a very, very small movement to get a big enough change in POI.
Each 1 degree on a circle is divided into 60 minutes, in turn this is divided into 60 seconds.

With most scopes each scope click = 1/4 MOA, which = 15 seconds of movement. So you see you only need very little movement to cause a big POI change.

sean raff · 01-10-2015 8:36pm

Had the same problem with mine .was shooting remington with shamrock grouping. Remington stopped coming in my cal .tried every other brand even though about reloads.Was told about ppu but was wary but gave it a go with great results. The sako seem to be bullet sensitive. Regards sean

Longranger · 02-10-2015 2:12pm

Thanks guys, we're going to sit down today and try all of the above and see what happens. Fingers crossed!

Cass · 03-10-2015 12:36am

Did you have similar problems with another rifle?

Longranger · 03-10-2015 4:35pm

Cass wrote: »

Did you have similar problems with another rifle?

It's not my rifle Cass,but the same lad always bought either cz or remmy. Never had this problem before. I had similar problems with my remmy swift but thanks to you guys here I got it sorted. A good strip down and very careful putting back together, and, together with the right ammo ( didn't like federal or even hornady! but loves remmy) and and she's shooting like a dream.

Cass · 03-10-2015 9:39pm

You have the process nailed so lad. Strip her down, check everything, assume nothing is right, and set it back up again. Try different ammo and a good shooting position.

As i said before lad, and it's a standing offer, i can bring you to the range as a guest and help you out if you cannot sort it out or nothing jumps out at you.

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sako 75 accuracy problem

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