I am on the verge of perfecting a bad *** load with the soon to be banned Speer bullets.(CaliforniKus) If I shoot the Speer bullet for a while then later switch to Barnes copper, will I have altered the future accuracy capacity of the barrel. It's a fairly new Tikka with only 150 rounds down the tube so if I will negatively impact the future accuracy I will bite the bullet and write off all the work and expense now.

Polishing the barrel with the Speer bullets might make it foul less.

There is no guarantee that the Barnes bullets will shoot worth a flip in your rifle before or after the Speer bullets.

No.
I would clean it out with copper solvent anyway.

by shooting it with anything high pressure you are gonna glaze, crack and erode the throat.
sierra speer whatever, if the rifle quits shooting well just get a new barrel put on it and keep on going.

You will be fine. Just use a good copper solvent before shooting the barnes. I switch back and forth with no problems. The Barnes TTSX is better than the TSX and accuracy has been fine to great. Be sure to use Barnes reload data as it is different than others due to the solid nature of the all-copper bullets and the fact that they are copper and not a copper alloy.

In my .270Win the Barnes bullets always group a little to the right and lower on the target. Why I do not know, but it must have to do with the shape etc of the bullets and resistance to the barrel.

I have stopped using Barnes bullets for the following reasons:

The mushroom diameter from the Barnes bullets is far less than any Hornady Interbond or Nosler Accubond bullets. The later bullets makes a larger wound channel which helps the bleeding process and results in a quicker kill. I had recovered a .270Win Hornady Interbond bullet with a mushroom of 16.8mm. This is nearly 3 times the bullet diameter of 6.8mm. With Barnes bullets the mushroom of one bullet recovered was only 11.5mm. I have found the Hornady's and Nosler bonded bullets always give you a retaining weight of between 80-85% on heavy boned animals. Penetration was not as good as Barnes bullets, but it kills much quicker. It is true that the blood clotting underneath the skin of the buck is a little more with the Interbond/Accubond bullets, but it is still far less than other ordinary bullets. It is a question whether Barnes would compromise their retaining weight philosiphy for a larger diameter mushroom on their bullets.

Personally I think Barnes could experiment on making the hollow point a bit deeper. This would expand their bullet better. I have found this to be of significant value with hunting larger species like Kudu and Blue Wildebeest. I have found that bucks shot with Barnes bullets usually run much further if shot just behind the front legs. With the Accubonds and Interbonds it might be 1 or two steps. I know this is not scientifically proven, for the reason that no 2 bucks are shot precisely on the same spot, but it is my experience over several years with different species.

Lastly I know Barnes bullets claim that their bullets do not increase wear on the barrels, but nobody according to my knowledge has scientifically proven this to be correct or not.

No.

I also switch back and forth between Barnes and cup-&-core, sometimes cleaning between and sometimes not.

I would suggest to start with a clean barrel though, and I like Wipe-Out or BreakFree foam copper removers.

After getting squeaky clean, your rifle may (my 1966 M70 in '06) or may not (Sako in 222remmag, TC Icon in 243) need a few rounds to foul the barrel and give best accuracy.

I am old school and have not found anything that the old copper and lead bullets won't kill so I never shoot the new fangled solid copper ones. Not to mention I do not want to pay the high prices for them. I know, the new stuff is so much better in so many ways, etc...I guess I will never know. Or care.

Your barrel will never know the difference between Barnes and other bullets. The copper fouling issue went away with the old Barnes X bullets. Since they came out with the TSX and TTSX they show no difference as far as the copper fouling issue and the accuracy has been on par with cup and core bullets.

To be honest I have got better accuracy from TSXs and TTSXs for a long time now. Here is an interesting comparison.

Bullet on the left is a 30 cal, 180 grain Sierra Gameking that impacted a 70 lb Texas whitetail doe at around 2800 fps in 2001. It was a Texas heart shot--I figured a 180 grain 30 cal bullet at that velocity should have enough penetration from ANY angle on a small doe. The bullet went through the right ham and stopped in the stomach. It mushroomed to .65" and weighed 110.9 grains. The deer required a finishing shot. This bullet would group around .6 to .7". The rifle was custom built on a Rem 700 with a 26" Pac Nor #4 contour barrel. It weighed over nine pounds with the scope.

The bullet on the right is a 30 cal, 168 grain Barnes TTSX. It impacted a 170 lb Oregon Blacktail buck in the chest at around 2875 fps in 2011. The bullet penetrated all the through, making jelly of the internal organs and was found deep in one of the hams. It mushroomed to .64" and weighed 166.9 grains. This buck was full in the rut, swollen neck and all. He went 20 feet and fell over after impact. This bullet groups 1/2" or better. The rifle is a custom M70 Classic with a Benchmark factory contour (#2) barrel 24" long. The rifle weighs 7.75lbs with the scope.

The bottom pic is some representative groups I have shot with the TTSX in this rifle.

From my perspective, there is no downside to the TTSX.