I recently purchased on of the Talo G45.5 with factory cut Aimpoint ACRO P2 optics. Naturally, the thought crossed my mind to swap the upper with one of my G19.5 lowers. Of course, this begs the question of what degree of zero shift (if any) should one expect when swapping lowers. I’ve dabbled with this question before getting into carry optics. However, the width of Amiglo HD front sights is such that precise groups beyond 15-20 yards is more a limitation of the sights rather than zero shift. The 3 MOA dot allows more precise estimates.
Here is a 5-round group of 124 grain SB from the G45.5 fired at 25 yards from a sandbag:
Here is another 5 rounds fired from the same upper on a G19 lower:
The far left round is probably more me than the gun. As you can see, minimal to any zero shift. Overall group size is roughly similar.