ingwe - I do not qualify as a "Tikka nut" but I do have experience with a couple of sporters in 223.
The first one was a pre-Beretta T-3 sporter with a beautifully figured wood stock and blued barrel, it was chambered in 223 with the 1-12 twist, it was the best shooting, mass produced, 223 I have ever owned, it did not care what weight of bullet (40's thru 55's) or what maker it was, and the same for any powder that is appropriate for 223's. It was a consistent sub 1/2" for 5 shots rifle, nothing was done to it except to adjust the trigger to just under two pounds of pull, unfortunately in a moment of weakness I sold it to a friend and have regretted it ever since.
Which brings up the tale of the second one, I missed the handiness and accuracy of the one I had sold and could not find another one in a wood stock which struck my fancy so I ended up purchasing another T-3 sporter, but this one was the synthetic stocked and blued version with the 1-8 twist and by this time Tikka had been purchased by Berretta. This rifle was a consistent sub 1" rifle for 5 shots but I could never get it to shoot even anywhere close to as consistent and as small groups as the first one. I tried every powder, bullet make and weight combo that I could come up with and none would do the magic 1/2" mark.
I have also owned two Tikka (pre-Berretta) model 595 heavy barrel models with 1-12 twist and like the sporter 1-12's they were easy to load for and both shot sub-1/2".
Now this is a very small sample and is my only experience with the 1-8 twist so it is not meant to be definitive but rather a report of my experience with the one and only 1-8 twist Tikka I ever owned.
