ATLDave said:
The striker/sear interface is applying force to the slide when it is cocked/tensioned. I am conjecturing that this force is, perhaps subtly, changing how the barrel and slide are coming to rest in relation to one another.
As you said, our comments are all just conjecture. Mine might just be a "scientific wild-a$$ guess.
The striker/sear may be applying force to the slide, but that doesn't mean the slide and barrel alignment is affected by that force. But the movement required to change the point of impact is not trivial.
- If the gun is shooting 6" low at 20 feet, the barrel would have to drop roughly 1/8th of an inch to cause that much error. (That was determined by using the Brownells Sight Correction Calculator -- which indicates the amount of sight change needed to get POI back to the POA.)
Generally, the only slide and barrel movement likely as the bullet is moving down the barrel is horizontal until after the bullet has left the barrel. (There can be a trivial amount of recoil-induced barrel rise) but it really is trivial The bullet leaves the barrel with most guns after a mere fraction 1/10th an inch (or less) of slide and barrel travel.
To get a lower point of impact, the rear of the slide would have to be moving UPWARD
or the front of the barrel must be moving downward (or a combination of both)
before the bullet leaves the barrel. Is there enough space for either one to move that much with only a fraction of an inch of slide movement? Is slide to frame fit or barrel to slide fit that loose? And would striker-induced force transfer be enough to do that?
If the top of the slide wasn't so flat, you could put a coin on the top of the slide and see what happens when the striker is released while dry-firing.. Wonder what a ball bearing would do, when the striker is released as the gun is dry fired? It would be interesting to see if it rolls forward.
I suspect something else is affecting the LOW LEFT results, but I don't have a clue as to what that might be.