Yes, multiple Glocks that I have owned had one or two malfunctions in the first ~150 rounds, and then no more. Inevitably, it will be with light "range ammo" and the malfunction will look exactly as if the cartridge was underpowered. I haven't seen this happen when using hotter self-defense ammo.
Not just with Glocks -- .22 autos do this quite often, too. The gun is just more reliable with a broader spectrum of ammo after a few hundred rounds.
Generally, the gun is *not* at peak performance as it comes straight out of the box. It may be "good enough" (and often is with a Glock), but spring weights and metal-to-metal contact surfaces are changing more quickly in those first few boxes of ammo than they are later on. Ever notice that magazines get a lot easier to load to full capacity after one or two trips to the range? That property is not unique to magazine springs.
Not just with Glocks -- .22 autos do this quite often, too. The gun is just more reliable with a broader spectrum of ammo after a few hundred rounds.
Generally, the gun is *not* at peak performance as it comes straight out of the box. It may be "good enough" (and often is with a Glock), but spring weights and metal-to-metal contact surfaces are changing more quickly in those first few boxes of ammo than they are later on. Ever notice that magazines get a lot easier to load to full capacity after one or two trips to the range? That property is not unique to magazine springs.