G'day from Down Under - Looking for advise on maximising Tikka T1X Accuracy

I'm currently going through the process of trying to extract the most accuracy I can out of a little Tikka T1X in 22lr (16" barrel version) that I shoot at my local benchrest club against the more typical and heavier Anschutz and the like bench guns shooting 20m, 50m & 90m. Down here in Aus, there isn't anything really similar to the NRL22 / factory category type competitions that you guys have in the states and my local club refers to this category as 'Bunny Gun' (in a slightly derogatory but good humoured way). As such I thought this forum would be a good source of more relevant knowledge and experience to draw upon.

I really enjoy shooting my Tikka and it already shoots pretty good (typically 5 shots into .3' to .4" at 50m with Eley Match shooting off the bench with a bipod & rear bag, using a Delta Optical 6-24 x 42 scope). I've even won a few club shoots (I don't think some of the Annie crowd were to impressed at being beaten by a 'Bunny Gun' ).

I've recently gone down the rabbit hole of trying a Lowey Tuner (Australian manufacturer) with reasonable success at 50m, but so far I've found the settings that improve accuracy at 50m (55yds) have inconsistent or even negative effect at 90m (100yds). I was inclined to blame my technique or wind calls until I did the 90m 'With' & 'Without' tuner comparison, which showed I could achieve much better consistency without the tuner than I was getting with it. As such, I'm inclined to walkaway from using the tuner, but thought I'd give it one last chance see what insights you guys might be able to provide. Any insights on any or all of the following would be appreciated:

1. Has anyone tried a tuner on a similar set up (short 16" or similar medium weight barrel 0.72" at the muzzle)? and if so what were your results like?

2. With a tuner on a 22lr do you typically use one setting for all distances? Or have you found that you need to use a different tune/setting for different distances? I've read several different & often conflicting theoretical posts, but I'm interested in real world findings with similar rifle setups e.g. more factory/sporter & less benchrest/custom.

3. 90m (100yd) results with the tuner tend to have more vertical spread than without the tuner - is this perhaps indicating that I've selected the wrong node?

I was thinking perhaps it was inconsistent rear bag pressure (my 50m groups show a little vertical spread as well), but when I did a comparison of CCI SV, Eley Match & SK Flatnose (multiple 10 shot groups at 90m) both with & without the tuner (see bottom pic) it indicated that I was getting less vertical spread and generally better consistency without the tuner then I was with the tuner.

Tuner & Tuning process - The Lowey Tuner is a clamp on design (you provide barrel diameter 2" back from the muzzle and the bore it to a close slip fit, then pinched up with 2 studs), which has has 50 increments marked per rotation and 10 full rotations of adjustments (500 total settings), so I shot 3 control groups at the top of each page (highlighted in yellow) without the tuner, then started the tuner testing at '0' revolutions (closest the chamber) and fired 3 shot groups working outwards towards the target in 10 setting increments (1/5th of a turn), each row of 5 bulls therefore represents 1 full rotation of the tuner.
By the end of the first page, the wind was threatening to come in, so based on the pattern emerging of the '10' setting in each rotation looking quite good, I skipped ahead and fired a shot group on each rotation at the '10' setting (5:10, 6:10, 7:10 etc) to see if there were any stand out rotations to focus my efforts. The wind conditions didn't end up deteriorating, so I went back and filled in all of the other 3 shot groups. The 8:10 to 8:40 range looked the most promising so I started trialling 8:25 & 8:30 settings in the weekly club shoots (20m & 50m) with promising results as shown below, however the results were far less consistent at the monthly 90m shoots, hence the 90m test to compare the ammo that was giving the best results at 50m (CCI SV, Eley Match & SK Flatnose) with and without the tuner.

Apologies for the lengthy first post... Here's a few picks of my rifle with tuner fitted (this was back when I was using a Vixen 4-16x scope before switching to the Delta) and examples of typical results.

The coin in some of the pics for scale is an Australian 5 cent piece 19.4mm (or a hare over 3/4") and the USBR target used for tuning was printed about 1/2 scale (A4 pages).