I've tried a ton of powders. You can use fast powders in the burn range you listed for 308 type powders. One of my best results was with IMR 3031 at 36.6 grains withb130gr Sierra game kings. My old Speer manual has load data for 3031.
All my stuff is super hot, you would have to work up safely
36.6gr 3031(130gr bullet)
38gr 4064
43gr win 760
41gr Ramshot hunter
45gr H4831SC
44gr Superformance
44gr N160
49gr N165
Your loads are not over listed Lyman #50 maximum, so not "super hot"
They look like pretty decent loads to me as most 6.5 cartridges seem to perform better when loaded close to the maximum of the particular rifles they're chambered in.
The original #44 bofors powder that was used by Sweden, Finland, Norway and Denmark for their 6.5x55 chambered M96 and Krag rifles had a very close burn rate to IMR3031 and they used it for both the 140 grain and 160 grain bullets.
The only thing powder burn rate will have any effect on is velocities and sometimes accuracy nodes.
In the past, I've played with charges of pistol powder in cartridge cases, such as 308Win/30-06 and the 6.5 Japanese.
The powder was 2400, which is one of the slower powders.
They worked quite well as long as I was careful to work up the loads and fill the air space remaining in the case with Dacron fibre.
Powder speed for any particular cartridge case isn't written in stone, however, before making changes of any kind or utilizing those not listed in manuals, you need to know what you're working with and how to "make do" to keep everything within safe parameters of not only the firearm but the components of the loaded cartridge.
You can't expect to get similar performance with ''make do" loads as those listed in manuals. The loads listed in manuals use powders that some very knowledgeable people felt would perform the most efficiently and with the least amount of issues legally.
The 6.5x55/7x57/7.62x53/30-06/8x57 and even the 303 Brit are all popular cartridges that come with a very wide spectrum CAVEAT.
All of them were chambered in several different action types that ranged from weak to very strong.
Right now, the 6.5x55 is one of the most beleagured cartridges out there. MOSTLY FROM LACK OF KNOWLEDGE.
The M96 type actions look to be very strong and IMHO are quite strong but they still have their limitations.
Because of this, people try to load them beyond their capabilities. Often they get away with it, until they don't.
The Mauser 98, Remington 700 types, Winchester 54/70 and a myriad of other popular but modern actions are just much stronger and bring new life to these old cartridges, by allowing more appropriate and efficient powders to be used to gain a couple of hundred feet more velocity and often better accuracy.
The loads I shoot out of my 6.5x55 chambered Tikka T3 perform slightly better, velocity wise than the 6.5CM with any given bullet weight and configuration. With two T3s shooting side by side with max loads in each, there wasn't any perceptible accuracy difference and the 6.5x55 gave appx 100fps more velocity than the 6.5CM.
If I were purchasing a new rifle today, the 6.5CM would likely be my preference though. Mostly because of the availability of good cartridge cases, from all of the top manufacturers.
I have a load for my Tikka T3, 6.5x55 that shoots 140 grain bullets consistently into less then 1moa at 100yds at slightly over 2800fps, SAFELY, with IMR7828ssc, from a 22in bbl. I WOULDN'T EVEN CONSIDER USING THIS LOAD IN A M96 type rifle.
I don't give any of these handloads away and won't even give the recipe for the load to anyone, unless I know the rifle they're going to use it in and trust their integrity to the point they won't put them in ''weaker'' actions.