Barrel temperature affecting accuracy

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dlau

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I bought the Tikka T3 lite in .308, and have had some problems getting consistent results, even while sighting in. After zeroing it in at 25 yards, I tried to replicate the 1 MOA guarantee at 100 yards. I found that it was difficult to get a good group, and that most of my shots were scattered high and right.

So I then try to eliminate the causes. I kept the scope settings (Burris fullfiled II 3X9) static, and I had a few trials to try and eliminate me and sloppy technique as the problem (still working on that :redface: )

Anyways, I was fortunate enough to borrow a shooting vise (big clamp) from the shooter next to me. He also pointed out that I should let the barrel cool down, at least a few minutes between shots. Great, so with the vise I could at least eliminate my sloppy technique.

I gave it a few minutes rest, placing my hand on the barrel to check temperature. I think fired a round- 2.5" above bull and 1/2" to the left. I let it sit for a few minutes... fired a second- 2.5" above bull and 1/2" to the right. Ok, not too bad...

We then did a target change (10 min wait) and I fired 4 shots, waiting a few minutes in between.

First shot was 6" high, and 2" right. subsequent shots were all about 1.5" to 2" right, and the 4 shots created a 4" vertical line with about 1" drop in elevation for each.

So I'm :confused: with the results. I have the rifle in a shooting vise, the scope was just mounted and sighted by a gunsmith. I am using IVI 7.62 rounds and I've also tried .308 Remington FMJ with similar results.

I'm wondering what conditions does Tikka shoot their rifles to create the 1 MOA guarantee... and if barrel temperature has this much of an effect?

I know the T3 lite is more of a hunting rifle, but I'm now a bit envious of my buddy who shoots his M-14 round after round with consistent accuracy. ;)

I will say that before getting this helpful advice, I was shooting 1 round after another with maybe a minute and a half between rounds? And yes, I was all over the place- mostly high and right. 2 shots would be side by side, and a third would be inches off...
 
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Don't know what you mean by a vice. Try with a sandbag under the forend, another under the toe of the stock. Pinch the rear bag to control elevation. Try to hold the rifle consistantly. Try something other than IVI ball. I would question whether the ammunition is capable of consistant moa from any rifle. See if you can find some Winchester of Federal Match ammnition. Are all the screws snug? Action, scope, etc. Don't worry about where the group is on the target, its the size of the group that matters.
 
I'm assuming by your post that you are shooting a .308 Win. and I would try some factory ammo instead of miltary 7.62 ammo. It may be corrosive primed as well and could cause damage to your rifle if not cleaned properly.
 
I set up a TRW M-14 with NM bedding job. With a scope, from sandbags, off a bench, I tested it with Cz., Yugo, FNM, WCC, and IVI ball. The cheapest, either the Yugo or CZ, I forget which, shot about 1 1/4 moa, the WCC and FNM about 2 moa. The IVI ran close to 3. DA ball, on the other hand had a reputation for accuracy, most all lots being at least as good as US NM, with some lots being outstanding. The Hirtenberg sold a couple or three years ago was good.
To give any rifle a real accuracy test, you don't want the ammunition to be a question mark.
 
Garbage in, Garbage out.

Ball ammo is 2 to 3 moa rated. If you have machine gun ball, the dispersion is even greater.

Go to Cdn Tire or Walmart and buy yourself a box of better factory ammo. I just did a quick test with the Win 150gr SP grey box Winchester 308. Shot 3/4" out of a box stock Savage.

I am sure it will give similar results in your Tikka. If you haven't done so, bed the action to the stock.

Jerry
 
agreed 100% with this statement...mine will shoot into an inch easily with the 150 grain federal....exactly the same rifle you have ,Tikka T3 Lite;)
mysticplayer said:
Garbage in, Garbage out.

Ball ammo is 2 to 3 moa rated. If you have machine gun ball, the dispersion is even greater.

Go to Cdn Tire or Walmart and buy yourself a box of better factory ammo. I just did a quick test with the Win 150gr SP grey box Winchester 308. Shot 3/4" out of a box stock Savage.

I am sure it will give similar results in your Tikka. If you haven't done so, bed the action to the stock.

Jerry
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Great points. Well I gave it a good cleaning, tightened the screw behind the trigger, and will be using Remington 150 gn. Let's hope this makes the difference.

Chola, how long do you wait between shots? Or does it matter much once the barrel reaches a certain temperature?
 
I would fire off 3 rounds in about 3-4 minutes..leave it cool while I played with something else...then try again..it never really got hot,but that's what I usually do with all my rifles
 
The Tikka has a 1:11 twist making it a barrel with a decided preference for heavier bullets. Military ammo is very light (I have 7.62 surplus for my M305 that is 147 grains). My TikTac in .308 is horrible with light ammo.

I would switch to 180 grain ammo and if you are getting serious, I would urge you to get into reloading your own. Seating depth with the Tikka seems to make a huge difference too.

Temp can be an issue for sure, expecially with light factory barrels, but if you keep it to 1 round per minute and only chamber the round when you are ready to shoot (Leaving a round in a hot chamber will throw off your zero) you should be able to work around that.

Good luck!
 
Here are my targets from today with my 308...first batch of handloads in her worked out pretty good,good enuff for me anyway..this is with a 6 power scopechief as well....had slight crosswind,but nothing overly serious
IMG_0015.jpg

IMG_0016.jpg
 
Very nice shooting.

One thing that can help with your shooting is to change the target style. With a 6X holding dead center, you have no real aiming point. You try and box a white square. With most reticles, the error in your crosshairs is about 1/4".

So try again using a target with a thick cross or line up using one corner of the square. With a bit of time getting used to moving the cross hairs so they just cover or meet the edge of the target, you will reduce your groups by as much as 1/2".

All of a sudden, the flyers close up (this assumes the ammo is up to the task) and you end up with very nice big hole groups.

The rifle is certainly more then adequate for the task but this aiming trick just builds more confidence in you and the potential of the gear.

This aiming error is why many shooters do so much better hitting a small object then aiming at a printed target.

Jerry
 
mysticplayer said:
Very nice shooting.



This aiming error is why many shooters do so much better hitting a small object then aiming at a printed target.

Jerry
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This is so true...I can hit cans and golf balls without any problems,but that darn paper gives me some trouble..LOL.....I'll try a different target for sure...gonna scope it with a Leupold 4-12.......I have a B&L Elite 4000 in 6x24 AO on the way,but it's far too big for what I need..but may try it for some groups and see;)

Sorry for the hijack on this thread:redface:
 
Are you aware of the problems heat waves from your barrel cause while looking through them with your high powered scope? How that affects accuracy and point of impact?
 
guntech said:
Are you aware of the problems heat waves from your barrel cause while looking through them with your high powered scope? How that affects accuracy and point of impact?
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Ye sir I am...not really a big fan of the high powered scopes....a 4-12 would be perfect for me....am just gonna try it out and see,basically more or less to test the scope out;)
 
I have in the past been lucky a few times buying a gun that shot factory loads that had a tight group. If you get into reloading you will see how a different components affect the guns accuracy.
 
Shoot your first round, see the bullet hole? aim at that hole for your subsequent shots. Really tightens things up, or you can just mark your target with a magic marker which is much quieter, but I like a fouling shot. If still not happy, buy a Savage.
 
dlau said:
First shot was ... 2" right. subsequent shots were all about 1.5" to 2" right,
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The vertical line sounds like an ammo prob to me. If it was the barel, the group would not nececarily be vertical. It sounds like the velocities are not concistant so you are getting some shots that drop more than others. The horizontal accuracy attests to the accuracy of the gun. You are only getting .5" of horizontal seperation, and if you get some ammo that your gun likes I immagine your virtical seperation wouldn't be much more. Just my thoughts, and keep the penny.
 
Obtunded said:
I would switch to 180 grain ammo and if you are getting serious, I would urge you to get into reloading your own. Seating depth with the Tikka seems to make a huge difference too.

Good luck!
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What kind of seating depth are you using, just starting to reload for my tikka 270, she's been a 1'' to 1'' 1/2 shooter but i'm sure she can do better...

pilot
 
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