Have you ever seen an independent ammo review that measured pressure? I haven't. The equipment to measure pressure is too expensive for anyone except ammo manufacturers. And I wouldn't be surprised if it was too expensive for most of the boutique companies like Buffalo Bore.

After decades of seeing ammo makers greatly exaggerate their velocity claims until affordable chronographs made it hard to get away with I am not going to take their word for it when they claim they can get more velocity than everybody else without going over the SAAMI limits.

I once read an article about the Super Vel ammo from the 70s. This was ammo from the company that went bankrupt in the 70s, not the one making ammo recently under the same name. The author talked Black Hills into pressure testing it and it was about 10% over SAAMI limits. Ammo makers seem to have a "thou shall not speak ill of other ammo makers" rule when it comes to other companies that are still in business. I doubt they would agree to pressure test ammo from Buffalo Bore or Underwood.

I suspect a lot of the "full power" loads from small companies known for hot ammo are going over the SAAMI limits. Not by enough to blow a gun up but enough to cause malfunctions and accelerated wear in some guns. Basically +P loads for cartridges that do not have a +P spec. Nothing wrong with having ammo like that as a choice but it should be labeled as such. Which is kind of what Buffalo Bore does with their "Heavy" loads.