I'm kind of confused as to where you got this impression...
That said why shoot full on loads at 100? I have H4895 on hand as a rule, so why not train with reduced loads? I have abandoned the idea of a cheap 6mm projectile for short range because there isn't much cheaper than a Hornady 105 gr Match to begin with. The vast majority of my training will be with my HBAR, and what I'll use shooting at Petawawa. I'd be a fool not to train with the 6mm CM though and show up at a match after just spending time behind the HBAR. My local range is only 200 yds., so why use twice the powder, never mind the extra barrel wear. When I get the chance to shoot past 200-300m I sure won't be shooting some pop gun load.
As for the milder cartridge, I had considered a 6mm BR...anyone know where I can get one for $650? I think it might take twice that, and a bit more.
Why not? It works, will be easier on your brass, barrel AND can be very accurate. There is a super accurate node in the 2700/2800fps range which is throttled way down from what is considered "typical". That is essentially what the 6BR should produce for velocity and you don't need to fuss with a shorter case. Ironically, the 6mm CM run at these speeds (2700/2800) will last longer vs a 6BR run at full throttle (pushing high 2800/2900fps).
wrt to bore life, there was a test done by Switzerland Army ( or maybe Austria) where they compare bore life vs pressure... all components the same... and of course done with the type of protocols the Swiss have become famous for. I assume this was to set their ammo pressure to maintain their MG's as long as possible.
Around the 40/45K psi, barrels lasted well over 10,000rds... wish I had the image cause memory puts it like 30 to 40K... it was a huge number vs the performance goals they had set.
they raised the pressures and as expected, bore life drops. As they went over 65k, the bore life plummeted to a couple thousand... so dropping operating pressures extend bore life? You bet and by a surprising amount. velocity difference was not huge... like 200fps.
I have seen 308win barrels burn out UNDER 1500rds using very toasty competition loads. There was a popular go fast load around 2012 that might cook a barrel just over 1000rds but it produced velocities that rivaled 300WM. it got banned by one of the National teams due to safety reasons... no kidding
Conversely, my buddy is bumbling along with an AR running a very moderate plinking load and has gone well past 12,000rds and the dang thing just keeps on shooting nearly as accurately as when it was new. And he is not gentle when he runs it. He practise IPSC/CQB type shooting and typical day is running drills 300 to 400 rds in a session and several mags for each run.
I am currently running a similar load in my 223 which is well past 2300rds which should be beyond it's prime but.... still rocking and enough for the Tac Div win at the BCPRL match. My practise/plinking load shot so well, I just ran it for the match.
finally, as I had mentioned on my Facebook posts and elsewhere, I have been playing with a 22 creedmoor and 6.5-284. Both can be VERY hard on throats with many showing problems under 1000rds. I am running them at moderate pressures, both barrels are in the 300 to 400rds and I can't see any change in the throat. I know F Open shooters who chase their throats every 200 to 300rds... mine, I think has just broken in.
So, load down that 6 CM and I fully expect your bore life to increase significantly, accuracy to be as good as that barrel is going to shoot, load tuning to be stable, brass life to be boring....
If you decide you need full throttle to shoot a match, you can always add more powder BUT if you are inside 1000yds, I don't think you are going to see much if any benefit.
Enjoy...
Jerry
