Horizontal stringing

[5Tom]

G'day all
I have a Tikka T3 Lite SS synthetic in .243 and have been shooting it for almost 4 years, while reloading for almost 2 years.

Since my Tikka has a 1:10 rate of twist, I decided to use the Hornady 87gr V-Max (or HPBT) with ADI AR2209 powder. Since Tikka rifles in the synthetic stocks are supposed to be "Free Floated", there has always been a small pressure point about 3 inches from the receiver that the barrel rests on.

Two range sessions ago, I tested out a promising load of 42.9gr and with a cold, fouled barrel, it gave me POA=POI. Now, I thought that was great, however I decided the remove the pressure points that afternoon believing it will improve my accuracy with a hot barrel. I used to shoot my rifle like a target rifle and send a few rounds downrange in the space of 1minute (which I have now realised that it's a sporter barrel and not a heavy barrel!!!)

Yesterday I took the rifle back out to Belmont to shoot the rifle in a much more controlled way by shooting one round every 10 minutes to keep the barrel cold. Again, this is with a 100% free-floating barrel with the pressure points removed. Sadly, my POI had changed dramatically and my accuracy had worsened.

I decided to pull the action out of the stock and place some gasket cork where the pressure point used to be and tightened up the screws, thinking it should return to how it was. My results looked promising (on a vertical scale) however my horizontal spread wasn't looking so good at all

2209-87gr-hpbt-corked-2.jpg (22.97 KiB) Viewed 5230 times

I've read that horizontal stringing is more shooter error? I also read on other forums, it can be rifle bedding (or floating issue). Should I keep the cork out and rework my handloads to suit the new barrel harmonics? Need help

[Blackened]

Sounds like you've checked this, but just to leave no stone unturned... There are plenty of rifles which are supposed to be free floated but have a contact point or two down the length.

Have you confirmed it's floated the whole length? Run a bank note between the barrel/stock all the way down smoothly?

If you hadn't said otherwise, floating issue would have been my first guess.

When you say "there has always been a small pressure point about 3 inches from the receiver that the barrel rests on", it's not unusual for the first 2" or so of barrel to be bedded after the action.

How much stock material did you remove to clear the contact point? A lot, or a small amount only?

[SendIt]

I've read that horizontal stringing is more shooter error?

On that subject, overall the group you're posted a screenshot of it about as high as it is wide...

If there was one more impact between the bottom group and top two, it would just about be round.

Not just having an off day perhaps? It does happen.

[5Tom]

Sorry, I forgot to mention the two shots above the horizontal string were shot under different conditions. I took one shot without the gasket pressure, then added the gasket and did 3 rounds in the center of the line. The following 3 shots were to the left and right of the 3 round group forming the line.

I then removed the gasket again and sent one round next to the first shot above the line.

Each shot was 10 minutes apart.

[AusC]

Loose scope rings or base?

Could be scope not holding zero, but that's less likely...

[Aster]

Assuming your scope rings etc. are all tight, it's sounding like a bedding issue.

Even though the pressure point you removed was causing accuracy issues once the barrel heated up, it might have been providing some stability to your action.

With that stability gone you might have exchanged heating accuracy problems for bedding issues - the action may now have a little movement in firing which it didn't before.

I'd do a full check on all action and scope screws, do another test group to make sure you weren't having an off day. Even get a mate to shoot it and see if he gets the same results.

If you have no luck after all that, maybe look at having it properly bedded?

[Lorgar]

One of the above is probably right.

One long shot to check is you're bipod if you're shooting off one.

I had a Harris bipod which wasn't quite right... When I mounted it it was all square, but when I fired the stock would rotate to the right 2-3mm and come to rest there.

When lining up my next shot it would settle straight again, then twist again when fired.

Took me a while to figure out, but after I replace the bipod my groups tightened up a bit.

[5Tom]

Thanks guys, I have a loupold vx1 scope and I replaced the tikka rings with a DNZ one piece mount a few months before. I also changed the tikka alloy recoil lug with a SS lug.

Do you think the cork gasket still gave lateral movement even though the action was tight?

[Herdsman]

Thanks guys, I have a leupold vx1 scope and I replaced the tikka rings with a DNZ one piece mount a few months before. I also changed the tikka alloy recoil lug with a SS lug.

Do you think the cork gasket still gave lateral movement even though the action was tight?

As long as everything is tight with your new mount and all that it should be right.

How thick is the cork gasket you're using? It could be allowing some movement compared to the original contact point as cork is obviously more flexible/compressible than synthetic...

[5Tom]

I think it's about 3mm thick.

The DNZ mount screws directly into the receiver, which I used nail polish as a lock-tite.

I have a Harris bipod attached and I used a rear sandbag to keep the rifle still.

[RealNick]

I think it's about 3mm thick.

Hmm, wouldn't surprise me if that compressed 1-2mm while when firing.

I reckon confirm your scope is ok, try another if possible?

Have someone else shoot a 7-8 shot group and see if the result is the same.

Failing one of those revealing the problem, I reckon see a smith about getting your rifle bedded. About $250 or so depending on where you go and should tighten up your groups and remove the possibility of all sorts of problems related to this.

[Hardcast]

No real reason not to leave the cork out, and try a 1/2 grain either side of the favourite load.
Two 4 shot groups and you might have an answer.

[Oldboy 7mm Dakota]

Just put it in a new stock as tikka stocks are hit and miss, and I had a 30.06 in 1 and it did the same as yours.
Replaced recoil lug and tried everything that was mentioned above to no avail .
Replaced stock and bedded it and shot like a dream.
Oldboy 7mm Dakota

[SendIt]

Just put it in a new stock as tikka stocks are hit and miss

That's an area more than 1 rifle maker struggles with

[Oldboy 7mm Dakota]

That's an area more than 1 rifle maker struggles with

Thats why I go for custom builds now as you can pick your own hardware,but you can still have some troubles with that.
But as a whole the rifle is by far better. The only trouble then is that you keep building different cals and selling perfectly good shooting rifles. I am building 2 more and thats it for me but my son just keeps on going as it has becomes a sickness.
we have 3 rifles that we are going to sell now that are great shooters.
Oldboy 7mm Dakota

[crys]

I am building 2 more and thats it for me

Heard that before

[Warrigul]

Since my Tikka has a 1:10 rate of twist, I decided to use the Hornady 87gr V-Max (or HPBT) with ADI AR2209 powder. Since Tikka rifles in the synthetic stocks are supposed to be "Free Floated", there has always been a small pressure point about 3 inches from the receiver that the barrel rests on.

Two range sessions ago, I tested out a promising load of 42.9gr and with a cold, fouled barrel, it gave me POA=POI. Now, I thought that was great, however I decided the remove the pressure points that afternoon believing it will improve my accuracy with a hot barrel. I used to shoot my rifle like a target rifle and send a few rounds downrange in the space of 1minute (which I have now realised that it's a sporter barrel and not a heavy barrel!!!)

Yesterday I took the rifle back out to Belmont to shoot the rifle in a much more controlled way by shooting one round every 10 minutes to keep the barrel cold. Again, this is with a 100% free-floating barrel with the pressure points removed. Sadly, my POI had changed dramatically and my accuracy had worsened.

I decided to pull the action out of the stock and place some gasket cork where the pressure point used to be and tightened up the screws, thinking it should return to how it was. My results looked promising (on a vertical scale) however my horizontal spread wasn't looking so good at all

(

A pressure point three inches from the receiver? I bed my rifles nearly that far out(I go two inches as a rule. It is not far enough to seriously affect harmonics or heat movement issues with a light barrel.

I have had a bit to do with TIKKAs and, as you have found out, the best route with them is to leave them alone. This even goes for the heavy barreled versions, I have worked loads for two that are absolute tack drivers and the equal of many purpose built target rifles.

I have never come across one that didn't shoot well out of the box(I am sure there are one or two that have had problems) and they are known for being one of the best buy and shoot rifles out there.
There really is nothing wrong with the stocks either. I have looked at four that were supposedly crap but with three it was either the scope or shooter that were the issue. The only one that had a genuine issue was bought secondhand, I had to replace the stock with a standard one after it had been bedded and floated, once I did that all the issues disappeared, it turns out the previous owner had been blaming the rifle when in all likelihood it was his poor wind reading skills at fault, he had been chasing problem that wasn't there.

My own TIKKA is also a SS lite in .243 and as it is capable of shooting less than three inch groups at 300 I can see no reason to fiddle. If I want less than half an inch accuracy I will drag out a target rifle.

My personal humble opinion is find a standard stock(there are a few out there).

Just my humble opinions, I am not a gunsmith.

[5Tom]

G'day
Forgot about this thread ha! I decided to shave off more material from the barrel channel to have a more "defined" air gap for a proper float. I figured if the barrel heats up and effects accuracy, it has to be touching the stock still.

I've since bought a Wheeler torque wrench and tightened the action screws between 40-45inch pounds as per spec. The other change I made was the projectile from a 87gr (v-max or HPBT) down to 70gr Sierra Blitzkings and tested more rounds. I also adjusted the COAL to 2.710inch, which is I believe a SAMI spec for .243 cartridge. Below is the load development results after the above changes. Next range session to make sure I'm on the right track