Why do Hornady and pretty much everyone else set such low max charges for the 6.5CM? First and foremost, LIABILITY.
No, 40.0 grains of H4350 is not compressed - nowhere near. - with the 140 ELD.
Like you, I started reloading many years (decades) ago. I too stayed between the min/max charge lines. I quit reloading bottleneck cartridges long ago. When I discovered a deep interest in modern long-range rifle and tactical competition, I swore I would just use factory rounds.As a retired engineer, I guess it was inevitable that I would relent and start handloading the 6.5CM. I am fortunate to have two close buddies with years of experience loading the 6.5CM, and they both told me to start at 40.0 grains H4350 with the 147-grain ELD-M. Even with the heavier bullet, I didn't start seeing pressure signs until 41.8-42.0 grains, and even then the sign was a very faint ejector mark. No issues with bolt lift.
So it does indeed seem that 41.2-41.4gr H4350 is the "chocolate ice cream cone" for the 140-147grain ELD bullets in bolt guns - pretty much everybody likes chocolate ice cream and pretty much all 6.5CM rifles (at least bolt guns; I can't speak for gas guns) like that H4350 charge with those bullets. I also found a node at 40.2 grains. I'm still deliberating whether the extra 100fps velocity at the higher charge is the standard I want to use for this rifle.
It took me awhile to accept that safe charges in current-production rifles can usually exceed the manuals' stated maximums - not always, but usually (there's my liability cover-my-butt statement). As another example, look at the .223 Remington. I grew up with that cartridge shooting a 50ish-grain bullet. Then came the 5.56mm NATO loading, and all the warnings that the 5.56 rounds should not be considered safe in a .223. Then I bought a .223 bolt gun... and started seeing 75-90 grain bullets approaching those 1960s-vintage velocities with bullets 2/3s lighter! Bottom line is, I found that I can shoot Mk262-spec 77-grain 5.56 rounds in my bolt-action rifle with zero pressure signs and great accuracy.
In no way am I suggesting that manuals' data should be ignored - especially by people new to reloading.