^ +1. I agree. Logic would suggest that if there's going to be a problem, it should show up sooner rather than later.
I think that the first and most important test - the "if it doesn't pass this test, don't pass GO" test, should be those first carry-mag fulls of ammo, dumped rapidly.
A good example for me would be my SR9c.
My SR9c just doesn't like the 115 gr. +P Cor-Bon DPX. Consistent failures-to-feed. I have 6 factory magazines for that pistol, and yes, this happens in all of them, regardless of whether if they're the full-sized 17-round mags or the shortened/"flush" 10-rounders. There were several stoppages within the first 10 rounds, and it didn't go away.
However, at the same time, there might also be issues that happen later in the time-line, and I think that this is worth considering.
For example, my Kahr PM9. As the gun gets dirtier from firing, my preferred 147 gr. Federal HST will start "hanging" the first round that's to be stripped from each magazine. Cycling/feeding is no problem with discharge of the pistol, but no matter if I power-stroke the slide or, as Kahr recommends, drop it via the slide-lock/release, on that first round out, it hangs for a half-beat before going home, and it happens progressively, as the feed ramp gets dirtier and dirtier. It doesn't happen with Speer's 147 gr. round.
Granted, it starts happening after the 50th round fired or-so - and it's very unlikely that, in a civilian application, we're likely to see that kind of round-count in a self-defense situation short of an all-out zombie apocalypse. :lol: But still, it's worth noting, I think, for the sake of due diligence, if nothing else.
So, like
Keltyke said, I look at the ballistics tests. In my case, with 9mms, I go by Dr. Roberts' list.
And in doing so, I've simply worked my way through that list.
I ended up picking the Federal HST because both the data seemed most impressive, and because for me, the recoil impulse was perceptibly different from the 124 gr. +P Speer GDHP that I previously standardized to.
We'll see where my Kahr ends up, in terms of the rounds I feed it. I've polished the feed ramp, and we'll see if that helps.
For me, I want at least 100 flawless rounds. From there, I start gaining confidence in that particular ammo, and I work up to 500. If there's no problems then, I just stop counting.
Range fodder? Who cares.

My failure rate with WWB 115 gr. 9x19 is somewhere on the order of 0.2 to 0.3%. I'm more than happy with that.
