Have been working with a Tikka T3x Lite .22-250 with 1:8 twist, and it has a particular dislike for the bullet for which I specifically bought it, the Hornady 75 gr. ELD-M. Namely, it double groups them or wants to. Generally when a bullet double groups the answer is to seat it deeper. If groups are circular but spread out the bullet needs to be seated closer to the lands. Rule of thumb for sure but I've found it works far more often than not.

The background:
- Scope is an SWFA SS 10x42 in Warne mounts, screws torqued to manufacturer specs which are 25 inch/pounds - I used 25 on the bottom and about 22 on top to be sure not to stress the scope tube. Screws are tight and the scope isn't moving. No other bullet double groups so it's not the scope.
- Action torqued into the stock per Tikka's spec - 44 inch/pounds front and back.
- Lapua cases sorted for neck concentricity, all 100 in the batch are at .001" or less
- Bullet runout is held to no more than .0015" on all rounds, a Lee collet die and Forster benchrest seater see to that.
- No particular pattern to the double groups, i.e. shots 1-2-3 here and 4-5 there, it will generally put 1-2 together and then 3-4-5 go back and forth in no particular order.
- Have tried two seating depths, .010" and .050" with all of the best loads. I tried a full .100" but groups went all to hell, plus the bullet is seated almost below the start of the ogive. .010" gives the best groups as can be seen, or I should say the best two groups.

Here is a series with the same three powder changes but seated at two depths. #2 and #3 in particular show the problem, two very nice groups spread apart. The same charges on the bottom row but seated at .050" show the groups spread out but still tending toward separate individual groups.



I removed the speed bump and fired these groups, the 75 ELD-M is the top two. Again, double grouping, albeit with a wider spread. Fwiw, the rifle rlikes the Hornady 75 BTHP which are the two bottom groups, you can see the exact same powder charges and same .010" seating depth producing respectable 5 shot groups with it.



Obvious solution is to go with the 75 BTHP, but that's not a loony enough answer, I'm hankering after the increased BC of that ELD-M.

My next step is to bed the action into the stock but I was hoping you folks could help me go over the litany of possible causes for double grouping in case there is something in front of me I'm overlooking here.

Your assumptions on seating depth is the general rule, but I've found rifles shoot much better when they are properly glass bedded. Too bad you can't make those double groups go away with a simple adjustment in seating depth, but obviously you've tried that. You can always try different charge weights. I see you only have 2 listed. Try increasing .5 grain at a time and see what groups do. It seems like most of you guys shy away from glass bedding, when that's the first thing I do to my rifles. It's simple and can be done in minutes....well, if you are good at it anyway... Also, since you say, "no other bullet is doing it", my question is why fiddle with that particular bullet?? Try a 77TMK or something of the like... You may find you don't even have to glass bed it, seeing how the 75gr Hornady is the only one doing it... I'm not going to show how my Tikka shot before and after glass bedding, but it's a huge difference...

Double grouping as you have pictured, first action screw torque, then look at bedding the rifle,https://www.ballisticstudies.com/shop/Video+Learning/Tikka+rifle+bedding+stock+and+action+preparation.+Part+4+of+Tikka+rifle+accuracy+series.html, ensure the scope is mounted ,oil free, and torqued to specs. Change scopes to verify that it is or is not the scope.

The double group can be tracked down to looseness somewhere in the system, be it action screws, bedding, scope mounts, and /or internals of the scope.

I have many Tikka's and they all have been bedded Foster style.

That’s on of those fake Chinese knockoff Tikkas.

I was gonna say scope mount screw hitting the bolt head but you’ve got clamps. Then maybe action screw, but it’s only with that bullet.

Tuning in for the rest of the story....

That's what I would do.

Rifles are like women. There's no accounting for their taste. They don't care what you think they should like, they are going to like what they like.

Once you figure out what that is, there's no point in arguing with them, just accept it and be happy.

Had a similar thing going on with a 25-06 I built, was pulling my hair out asking other guys questions, and doubting my ability to shoot anymore, ( don't shoot as often as I used to). I changed my rest and was trying to dry fire without the reticule moving , couldn't make it happen,it bounced every time, was refocusing and noticed the eye piece loose both visible and by feel. Worth taking a look at, luck that I noticed what was going on.A tikka that won't group is scarce.

I had a model 70 in 270, 1957 vintage that two grouped like crazy. I discussed the matter at length with several of the Campfire Illuminati and took their suggestions, re-bedding the action, floating the barrel, playing with the barrel screw, changing the scope. Nothing stopped the two grouping. The rifle couldn’t keep the two grouping under two inches at 100yards. Turns out all the rifle was trying to tell me was she hated Nosler bullets with a passion. I’m a Nosler first person and I just couldn’t believe it. Subsequent tests with the Sierra Gamechanger and Berger VLD’s both produced groups under a quarter inch.

Still can’t believe it nor understand it...

That's pretty much where I am at this stage.

Have loaded up a "one last try" batch of the 75 gr. ELD-M and its best load, 33.0 RL-15 at .050" and .090" off the lands, 9 rounds each, and 10 rounds with the 75 BTHP at 33.5 RL-15. Those larger round counts really show the trend of the load. Will also start experimenting with the Hornady 68 BTHP just for the heck of it although that goes against the primary goal of minimizing wind drift - it has the greatest drift at 500 and 1000 yards of the four bullets I'm comparing.

Plan B was to get a reliable 30 year old Model 700 rebarreled to .22-250 or .22 Creedmoor by Pac-Nor but I see they've burned down.

Oh well, if this Tikka .22-250 doesn't do what is expected of it that will give me an excuse to get a 6mm Creedmoor. That bests the wind drift numbers out of everything in the .22-250 except the 88 gr. ELD-M, which this rifle doesn't like either....

I was loading for a 30-06 that was double grouping and each of the groups was one hole. Pushed it harder by 1.5 grains and they finally pulled together.