Why am I shooting low?

[Candiru]

I went to the range on Sunday and rented their S&W 629 with a 4" barrel,
through which I shot some .44 Specials and Magnums. Although I was
fairly accurate with this gun when I shot it before, I was dismayed to
find myself shooting consistently low this time around. At seven yards'
distance, all my shots were grouping about 4" south from POA. I had a
good sight picture and don't think this was a flinch because of the very
consistent height of the rounds. (My bad trigger technique had them
stringing out to the left and right, but all at the same height.)

I'm more of a semi-auto guy, so my guess is that there's something wrong
with my grip angle, which would explain why I felt the impact of some of
the .44 Mags in my wrist, instead of on my palm. My understanding was
that you're supposed to grip a revolver higher up on the backstrap,
bringing the base knuckle of the trigger finger in line with the radius
bnoe in the forearm. I've been wrong a lot, though, so any advice you
could offer to improve my aim would be greatly appreciated.

 

[Six-Gun]

There's always the possibility of the sight comoing loos,e but to be honest, it's probably a flinch after not having shot such heavy loads for a while. Even fliching can be consistent, and consistently low shots are usually indicative of this, because your pushing the barrel down in anticipatio of the force actingin the opposite direction.

The way to test this is to put a snapcap or dummy bullet in the clinder and spin it without looking down at where the round landed, close the clinder. Focus only on the front sight as you shoot as to not give away which round is the dummy. Have someone watch you as you shoot, and see if they catch you pushing the nose of the gun down as you sqeeze on the inert bullet.

 

[pcf]

It's not yours, so no telling what has been done to it since the last time you fired it. You have no control over a rental and people do mess with the sights. If it was my revovler and my groups shifted I'd be concerned.

If nothing changed from the last time (same gun, grip, ammo, etc) and the groups are off, it's the sights.

 

[Six-Gun]

Oops - I totally missed the rental gun part. Yeah, pcf is right: someone could've easily messed with the sights between when you last fired it and now.