The "top" shooters use 6x47, 6.5x47, 6mm Creed, and 6.5mm Creed for PRS.

So why not use the 6mm Remington?

It can shoot 105 grain bullets.
It has a shoulder angle of 26• , almost 30•, more than old standard of 20•
Yes it uses more powder; can be an advantage.
Velocities of 2,900 +\- are easy.
Brass is readily available.
Yes it uses large rifle primer, but with more than 35 grains of powder, that is desired.

Phil, why not screw on a new faster twist barrel in 6mm Remington AI and let that dog hunt with the 115s. Just kidding then again perhaps not.

With a longer heavy bullets the rem would really need a medium action at the least and better yet a long action.

There's your answer...much like other things....it's all about the stroke

Could it be used- Yes. Why is it not?

1- It's a faster round than the 6mm Creedmoor, and others you listed. You can easily push a 105 grain to 3050, even to 3150 fps, in a 6mm Creedmoor. Most of you PRS matches have a speed limit of 3050 fps. That's already fast and can easily tear up the steel targets at closer ranges, with many shooters in a match. You don't need the extra speed the 6mm Rem offers.

2- The case design is much longer than a Creedmoor, by .313" (over a 1/3 of an inch). When you are running a match bullet, like a 105 Hybrid or A-max/ELD-M, the bullet will be seated further out closer to the lands. In a short action magazine, like the AI mags commonly used, your max case length (COAL) is about 2.860". In the 6mm Rem, you will have to seat these bullets well beyond the 2.860". Simply put, the 6mm is too long of a round.

3- There are much better case designs and more efficient rounds to use to get speeds up with less powder than the 6mm Rem. Having more powder equals more heat, and when barrels heat up, they become less accurate. So the smaller the powder charge you have, the better.

When the 260 Rem came out, it was the rage for comp shooters, me included. I loved the round, but it also had it's issues. To seat the 140 grain bullets in the 260 close to the lands, I was running my rounds at 2.920" COAL. That's LONG!!! I had modified my AI mags and opened up my feed ramp on my Surgeon action, just to get it to feed. I later went to the 6.5x47 L, and it is a much better case design and does not have the COAL and feeding issues of these other rounds. The 6.5 CM also solved the issue of the 260 Rem.

BAM. Drops the mike and walks off the stage.

I'm sorry, I forget his name (Michael, I think), shot a 6mm AI in the THF tactical shooting match this summer. His rifle shot really good and fast. He got second place with it. First place- 308 Win. He also stopped shooting some of the stages early with more time on the clock because he didn't want to burn his barrel up. That's another draw back of a cartridge with more powder, is more barrel wear for less barrel life.

He wasn't trying to save his barrel, he was spinning jackets right off the bullet when the barrel got warm. I taught him, while he was shooting that load. Boom, then about 70 yards down range, poof jackets disintegrated. I told him to run a heavier bullet for that twist or swap barrels. But did he listen to me, noooooo! He then shot my match with it, on a lighter load, and it was still doing it, but not as frequently. Then he made sure and get sqadded with me at the Red River West match, and it kept happening on Saturday. Sunday he came back with a whole new barrel, and load. I guess he didn't sleep that night. Sunday morning I told him "this is when you say to me, you were right". I cant write what he replied with.

LOL! Oh, I didn't know that!

Not trying to be THAT guy but this statement is incorrect. 0.313" is actually a little LESS than a third of an inch. FAKE NEWS!!!
Wait, being that guy more entertaining than i thought.

LOL! Yes, oops, almost a 1/3 of an inch! I was thinking .3, not .333"! Thanks!

I bought a Ruger M77 in 1976, 6mm Remington. I chose the caliber over .243 as I knew I would do more deer hunting than varmint shooting and the 6 is better with heavier bullets.
The gun shoots 0.5 moa out to 400 yards with handloads.
90 - 105 grain bullets.
When I bought it, My neighbor a Sako fan, told me the gun was junk - made with cheap Japanese steel. - So much for that statement.

I think I will rechamber / rebarrel the rifle after I shoot it out; to 6CM.
Got about 3k rounds thru it.

But it took me 40 years. Ha!