With some more reading on Internet - maybe the thing is related to the hardness of the bullet used. There is a "magic" relationship of about 1422 between Brinell Hardness and chamber pressure to be used. So, apparently not many have ever found out what actual pressures that manufacturers load their .22 up to - is known what SAAMI sets for Maximum - but appears few get close to that without very hard bullets. Apparently. So 40/1 lead/tin or similar going to be Brinell Hardness about 7 (?) - multiply by magic 1422 and you get roughly 10,000 PSI as the chamber pressure for that hardness of bullet. Note, is no reference to the VELOCITY of it - is about the PRESSURE generated by the loading. If one uses "soft" lead bullets, going to have lower pressures that are usable, versus "hard" lead bullets. I think. Coatings, jacketing, alloys with antinomy all work to make the bullet harder - to allow more velocity - which likely means more breech pressure. But I still can not find anything definitive about that - is all written as "should be"; "likely is" and so on.
That 1422 number is discussed in Chapter 10 of "Modern Reloading - Second Edition" by Richard Lee, for those that care to read up on how that number is derived - or at least Richard Lee's version of that.
So, I guess I am still looking to find out what is the lower, or lowest PRESSURE loadings available for modern .22 Long Rifle.
The manufacturers of .22 ammo are all using pretty soft alloys for their bullets, it runs through the swaging machinery a lot easier than harder alloys do.
I would suggest, based on many years of gouging .22 bullets with my thumbnail, that you are not going to find a lot of variation... Mostly just pure lead, as they have no worries about mold fill out. That is a Casting problem, rather than a swaging one.
On the main, I would take it on faith, that a higher velocity, equals a higher pressure load. In the case of some of the 'performance' ammo, like the CCI Stingers, they both upped the load (and used a longer case to hold it), and reduced the weight of the bullet, to get the performance.
As far as Standard velocity ammo, pretty much anything with a36-40 grain bullet, and 1100-ish or less fps, is where you want to be looking. Like I said before, I do like the CCI Quiets (40gn/800-ish fps), as they ARE quiet, and they have served me well doing pest management within normal earshot of golfers and other folks here on the place. From a longer barrel, they are VERY low noise,and what noise they do make, doesn't sound like a shot, really.
If your guns turn out to be decent condition, and not looking like they have been dragged over the Great Divide behind an ox, my opinion is that they will be fine on about any .22 ammo, if only for the short term. You reduce the wear and tear, in the long term, by sticking to the so called Standard Velocity ammo. Unless the guns are in REALLY disreputable condition, what you are dealing with , by using modern High Velocity ammo, is accelerated wear, rather than catastrophic failure potential.
Try not to read too much in to what happens with reloading info. The manufacturers do not use the same powders as are available as reloading supplies, generally. You can pretty much count on, that the loads are mostly reduced to get the lower velocities, and that they will be well below the max allowed pressures.
I would be quite surprised, actually, if I were to find out that any manufacturer of .22 ammo, actually used a separate type of powder, from product line to product line!
