After having shot 6.5mm Creedmoor for a year in PRS racegun matches, I realized that I would prefer to go down to a 6mm caliber so that I could better spot hits and misses with lower recoil, as my recoil management is not what it should be yet, so getting any advantage I can helps.
I decided to give a prefit barrel a try, as I had heard and read a lot about them, and was curious about how good they are and how quick the make the caliber and barrel change process.
What I like about these new prefit barrels, is the fact that you can quickly and for a low cost convert your rifle to another cartridge or caliber by fitting a different prefit barrel. You can for instance get a Savage Prefit Barrel from Proof Research chambered in 6.5mm Creedmoor, and then by taking off your old barrel, and putting this new prefit barrel on, you convert for instance your Savage 308 Win to a Savage 6.5 Creedmoor, you just have to ensure the action length and bolt face size of the two cartridges are the same, by checking a bolt face chart first.
Although you can do this yourself if you have the appropriate barrel vice and barrel wrench at home, you need to ensure that you torque the new prefit barrel to the correct recommended torque setting, usually around 100 in/lbs. The next important factor to ensure looking at, and why it is often considered better to just have the barrel fitted to the action by a competent gunsmith, is that after fitment, you have to check the headspace to ensure it is within the recommended specs for that cartridge. This is usually done through a go gauge and a no-go gauge. I have been lucky and each of the prefit barrels so far fitted, has had correct headspacing right away. My last one was a Tikka prefit barrel also from Proof research. But let us continue with discussing this particular barrel change.
The Barrel
Based on what was readily available to me and the Dies I already had, I decided to go for a Proof prefit barrel for my Kelbly Atlas Tactical action. The barrel was ordered and arrived a few weeks later.

As I do not have a barrel vise, and because I do not know enough about the process yet myself, I decided to take it to my local gunsmith to install for me, and to check the headspacing of the chamber and ensure that it is within acceptable spec.
Fitment
First the old 6.5mm Creedmoor chambered barrel was removed from the action.

After the high-heat grease was applied to the threads on the barrel, the new Proof prefit barrel was screwed into the Kelbly Atlas Tactical action, and torqued down to the recommended 100 ft/lbs.

The bolt was put back into the action and the headspace was checked with a go and no-go guages, and it checked to be within recommended specifications for the 6mm Creedmoor cartridge.
Barrel Chamber
After fitment, I checked the inside of the barrel and chamber, to see the quality of the chambering before starting to shoot.


Good thing I checked the chamber and barrel inside before firing it and before barrel break in, as you can see below, the prefit barrel chamber had some left over oil in it probably from the machining processes. I would not be good if shot like this as some of that oil can go down the barrel and cause hydraulic pressure when shot, damaging the barrel or causing it to blow up.

End Result
Here is the completed and assembled barreled action, ready to go back into the MDT ACC chassis which I am using it for in the PRS competitions. So far before barrel break-in, I am happy with the result and little effort it took to get the barrel swap done.
