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Mick Miller

Tikka 260 T3x odd groupings

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I wonder if anyone can help explain these odd results. I'm using ELD-X 143gn with N550 and have spent some time developing the load, tweaking seating depth but keep getting strange groups.

This is a typical example, an 8 shot group, of sorts, with five touching in one group and a separate group of 3 shots to the left and slightly higher.

This was shot at 208m with a very slight tail wind, with an occasional cross wind (from left to right). 

The loads are all measured as precisely as possible, to a few kernels of each other, bullets seated to the same depth, same case type, same trim length, same primer. The average velocity is 2600fps.

Action seems tight in the stock, torqued down, scope mounts torqued too. It could just be user error I guess, but it seems odd that I get some shots printing on one, tight group and others printing similarly close in another spot. 

The barrel had been threaded but the guy who did it knows his onions so I doubt that is an issue, the crown is factory cut however, and hasn't been touched. It is a new rifle and may just need a few more down it perhaps. 

Anyone seen this sort of thing before?

20180506_192218.jpg

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It looks like an inconsistent hold. Maybe you just need to get used to it more.~Andrew

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Perhaps, I shot my 243 just prior to this and those little 55gn bullets were just as laser guided as usual though. Even with the slightly extended range and small amount of wind.

I'm going to load some more and try again, I did concentrate on not breaking my check weld or lifting my head from the stock, just lifting the bolt, extracting the case. 

I'll shoot the next lot at 100m too. 

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New rifle new shooting dynamics. I have a CZ 527 Grendel that I am finally coming to terms with, performance wise. It's taken me about a hundred rounds to really get to know how to shoot it for group. Off hand in the field, no problem. I've already taken deer with it, but squeezing the smallest grouping needed practice. ~Andrew

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Why not try several difrent factory loads as a way of first running in the barel and second to give you a constant as it were? It's what I do with every new rifle.

some take a wile to run in.

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Suggest five shot group shot first (centre group) ?

Three shot second group after reloading mag?

 

Perhaps you have something in the barrel channel that is affected by the heat of the barrel - or the barrel is moving when heated after repeated shots.

 

Looks to me like possibly the barrel is moving when hot to produce two separate groups.

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You don't say which T3x Mick.check what Ronin said.i agree.i just looked and there is 22 different variations of T3x.if it's brand new then the stock maybe touching the barrel on one side or the other.that was the first thing I noticed on a T3 varmint I bought.sorted that out before I had taken any shots.

If it' a sporting barrel then heating up could cause poi change.

Something in the barrel channel you can't see.

Something too look at Mick.

I hope you sort it.

Atb No I deer

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It could be a couple of things:

- Bedding. The recoil lug could be in contact or as Ronin said, the barrel is contacting somewhere along its length which is causing issues when heating up.

- Forearm hold or flex or bipod loading. 

- Seating depth, though you say you've already developed the loads carefully.

Id try the following things before getting a more professional diagnosis & fix.

1. Just double check all screws & mounts, especially if using a muzzle break or moddy

2. Try a different shooter to rule you out of the equation. In theory, the gun would continue with the two groups regardless of who's driving

3. If using a bipod or freehand, try using a proper front rest. If you are using a rest, try pushing the rifle forward so it's resting less on the forearm. If there's flex in the forearm, resting the gun at that point will push the forearm and barrel closer together and cause issues.

4. Shooting some factory is a good idea. Might help to see if it's your load/bullet choice

If it's still showing a consistent 2 group pattern, then I suggest going to a gunsmith to diagnose. It's likely to be the bedding.

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208 metres thats nice grouping Mick.

Maybe Andrew is right.

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Thanks for the replies chaps, I'm out most of the day so typing this from a mobile, when I'm back later I'll reply to some points suggested. 

I will say that a different shooter produces similar issues, not quite as tightly grouped as this though as they were completely unfamiliar with the rifle, they can shoot though I'll say that much, regularly winning club comps. 

The model is the t3x super varmint. 

The rifle has been out of the stock so it could be a recoil lug issue, perhaps I didn't fit it correctly when reinstalling? I'll take a read of the other thread. 

More replies to follow, thanks again for your input. 

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You will know if the recoil lug isnt engaged properly as the action will be prod of the stock - the vent hole is usually flush with the upper stock surface - an easy tell if the action isnt sat in the stock.

 

 

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Try a different scope. Could be a loose lens. Happens to the best of them.

edi

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OP - with the two groups, when are they formed? Two possible scenarios;

Scenario 1: Is one group formed first, say shots 1-5, and then a second group is formed from shots 6-8? 

Scenario 2: Or are the two groups formed randomly. So shots 1-3 are one group, shots 4-5 are the second group, then shot 6 back to group one and then shots 7-8 back to group two? Or something like that.  

If it's scenario 1, i'd bet it's the bedding or barrel contact somewhere along the stock. If it's scenario 2, then I'd say it could be due to the scope or the rings, crown or something else.

 

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It's scenario 2. I did wonder whether it could be the crown, my 243 had a terrible crown and I could never get any accuracy until it was redone, then it shot like a different rifle. But it looked visually awful. The tikka looks pretty good, even when viewed through a loupe. I can't see any obvious burrs or damage anywhere. 

I'll check the mounts again too. Make sure that they're right but these were torqued to Warne specifications and not with a cheapo torque wrench either. 

Scope is a Bushnell DMR, so not shabby, not top of the tree either I'll grant you but it should be solid enough. 

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If the crown was gash then all shots would be all over the place, not two tightly shot groups in two different places

BTW, many people overthink this and put too much emphasis on the crown

Before looking into wonky crowns, barrel heating (a distinct possibility), what I'd do is leave everything as it is, don't clean it or anything, and then take it out and repeat the exact same procedure and see where your groups form. If it is more or less identical then I'd think about bedding/action movement or barrel harmonics/touching

If not then it's possibly you and an inconsistent setup, but you have to repeat it first

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It will be nice to know what it is.

A mate was shooting at 1000yds a month ago and had a cracking score.2 weeks later it started sending them always.he pulled out of the COF and noticed his picattiny rail was loose.it was second shoot with a new scope on.he couldn't of nipped up the bolts and they worked looser with every shot.not sure if he thread locked them and forgot to nip the screws up and they worked loose or thread lock had passed it' use by date and didn' secure them at all.he has done them up proper now.100 miles each way is along way to go with a wonky set up.

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They are Warne vertical rings. Not sure what issues you refer to though? 

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My immediate thoughts were rings or turret issues.  Have you a spare set of rings your could try, or another scope?

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13 hours ago, bradders said:

If the crown was gash then all shots would be all over the place, not two tightly shot groups in two different places

BTW, many people overthink this and put too much emphasis on the crown

Before looking into wonky crowns, barrel heating (a distinct possibility), what I'd do is leave everything as it is, don't clean it or anything, and then take it out and repeat the exact same procedure and see where your groups form. If it is more or less identical then I'd think about bedding/action movement or barrel harmonics/touching

If not then it's possibly you and an inconsistent setup, but you have to repeat it first

Sounds like a plan, before swapping scopes/rings etc.

It could well be inconsistencies in hold as suggested already, rather than mechanical. I'm going to rinse and repeat at a closer range and see what happens. Will report back. 

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Mick - lots of good advice as always BUT - you've shot a 'minute of angle' 8-shot group at approx 230 yards with a factory rifle, presumably off a bi-pod and no windflags - with a light but variable wind.  

What's the problem?  Let's be honest - to get the two groups any closer - in something like a half MOA group - would be phenomenal for a factory rifle at this distance.

If you want to find out more - get a decent front and rear support for your rifle and a few windflags.

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I would change the scope and rings.

I had a faulty scope that did very similar, the recoil from a shot seemed to move the reticule. It didn't do it every shot but it definitely moved between the same two points, I ended up with two very distinct groups at 100yds many times. I changed scope and the problem went away, I also sent the scope back and it was confirmed as faulty and replaced, it was a Vortex Viper PST 6-24x50

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All good advice. As stated I need to shoot another few groups to see if this continues to repeat, or if it's me. This seems the general consensus and it's valid. the initial groups were a little wayward, fairly spread but as the rifle has had a few more rounds through it the accuracy has improved, although still giving these odd inconsistencies.

I'm not ruling out the mechanical but I need to rule out the NBtB first. Although I've never experienced any issues with Warne mounts previously so not sure about that comment. Provided the bases are tightened before the scope it's always worked well for me. I may change the tikka  varmint picatinny rail though, it doesn't have the shelf beneath the mounts as per picatinny specifications which means the mounts are really only supported by the upper surfaces. I have a Barton GunWorks picatinny on order to replace this (allegedly not that easy as the tikka rail is threadlocked and glued on).

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Listen to MTLEADFARMER, vertically split rings cause this exact symptom.  It's been demonstrated numerous times.  Continued use of vertically split rings can damage the erector of the scope if the rings have been tighten improperly (both in torque, and order of tightening).  Even Vortex now asks as a matter of course when a customer calls in with a problem "Are you using vertically split rings?".  When one of the largest optics manufacturers in the US does this as SOP, it should tell you there is something to this.

Also, you need to ensure that you are pushing the rings forward, against the pic rail slots, as they are tightened down.  There is enough tolerance in the ring to base slot fit, that they can move under recoil, if not set up with both rings firmly butted up against the forward wall of each slot.


Finally, make sure the rings are actually clamping the rail properly.  I just had a friend send his Vortex AMG back, only to find out nothing was wrong with it.  When he got it back and remounted it, he discovered that the Seekins rings he had, had an out of spec foot (was too short/thin), so that when he clamped the rings down to the rail, it was gripping the point, and not the flat of the side of the pic rail (essentially pinching the rail, instead of seating against the rail).  You could literally see light between the foot and rail.

 

Your groups are too consistent to be just human error.  Something is moving, and in a repeatable fashion.

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