NATO spec for 9 mm (STANAG 4090) allows for a VERY wide margin of power. Now that most submachine guns have been replaced by assault rifles the rounds are normally loaded just a hair hotter than normal SAAMI specs, below SAAMI +P pressure in most cases. That is the case with modern (made in the last 15 years or so) 9 mm NATO ammo.
Regarding muzzle energy, the NATO standard is exceptionally lax.
According to STANAG 4090, the test barrel is 7.85", the muzzle energy must be between 400 and 600 ft·lbf, and bullet weight between 108 and 128 gr.
This means that a humble SAAMI spec 115 gr 9 mm load that has about 1140 fps in a 4" barrel, but probably does about 1260 fps in a 7.85" barrel (with 405 ft-lbs) meets the NATO spec. And a hot load that does 1475 fps with a 124 gr bullet out of a 8" barrel also meets the spec at the top end (599 ft-lbs).
In normal locked breech, recoil opeated pistols, recoil impulse (bullet mass*bullet velocity + powder mass*gas exit velocity) is what governs the cycle. It doesn't matter the chamber pressure or bullet type/weight, there is a certain window of recoil impulse that balances best in a certain design. The 9 mm case is exceptionally strong, but extra recoil impulse is what can lead to functional/durability problems. The glock 17 and all glocks in 9 mm have been designed from the ground up for NATO specs.
Last edited by TiroFijo; 04-08-2016 at 12:21 PM.
I haven't shot a whole lot of this stuff but it has never given me an issue. I haven't chronographed it but I would concur with what others have said that it is slightly hotter than regular practice ammo but doesn't feel as stout at +p loads. Last time I shot it in my 34 there wasn't much discernible difference in muzzle rise between it and the 115 grain Perfecta I was shooting and my split times were no different.
Better ballistic minds than I have already chimed in, so I'll just note that I like the "NATO" (note use of quotes) Winchester stuff just fine because it gives me a wider margin of error, in terms of function, when my shooting grip is compromised.
Frankly, I'm a lot more worried about underpowered range fodder (eg. PMC 115 ball) than too hot in a Glock. I'd only shoot 124+P GDHP if I could afford it in large amounts.
JMO