Inaccuracy of a Rail Mounted Laser

[wally]

If the laser is mounted to the frame - how does moving the slide affect the light?

I guess you didn't read my edited correction. I had a brain fart when I typed it, you need to clamp the slide and wiggle the frame to get an idea of the "slop" in the laser's alignment. This will likely be a bit worse that you might actually see when shooting as the barrel link/cam will try to put it back in mostly the same place after each shot. As I said, with my J-frame laser grips can be impressively accurate, on a tilting barrel auto loader not so much, but still usefully accurate at typical SD distances.

I'm not a big fan of laser sights, although I see situations where they could be useful, but its hard to practice with them unless you have a place to shoot in low light. I do think everyone should get a cheap laser sight for dry fire practice -- it really shows your trigger pull issues, if its "worth it" or not for the high quality ones for SD use is debatable IMHO.

 

[Merle1]

Most experts suggest that barrel to slide fit (with consistent, precise lockup) is critical with aimed fire -- when the sights are on the slide. Then, barrel/slide fit (and consistent lockup) is far more important than slide to frame fit.

If the sighting system is attached to the frame, barrel/slide fit is still critical, but slide to frame becomes more important. And, if the slide has some slop -- for reliability, perhaps -- or if the frame can flex or move (as might be the case with some polymer-framed designs), the alignment of the sighting system and barrel can be inconsistent from shot to shot .( I suspect that's why we see some polymer guns with their sighting systems mounted on the slide rather than the frame.)

That would surely affect accuracy/repeatability, but I still don't see how that would cause the dot to move around.

 

[Merle1]

I guess you didn't read my edited correction. I had a brain fart when I typed it, you need to clamp the slide and wiggle the frame to get an idea of the "slop" in the laser's alignment. This will likely be a bit worse that you might actually see when shooting as the barrel link/cam will try to put it back in mostly the same place after each shot. As I said, with my J-frame laser grips can be impressively accurate, on a tilting barrel auto loader not so much, but still usefully accurate at typical SD distances.

I'm not a big fan of laser sights, although I see situations where they could be useful, but its hard to practice with them unless you have a place to shoot in low light. I do think everyone should get a cheap laser sight for dry fire practice -- it really shows your trigger pull issues, if its "worth it" or not for the high quality ones for SD use is debatable IMHO.

OK, this makes sense - thanks.

 

[Walt Sherrill]

That would surely affect accuracy/repeatability, but I still don't see how that would cause the dot to move around.

Perhaps I misread (or made an incorrect inference), as I didn't realize THAT sort of wiggling was the concern. I had picked up on someone's earlier comment about some polymer frames "convulsing" during recoil. In that case, sighting systems attached to either an accessory rail or frame would be affected.

If you are talking about LASER sighting system "wiggle" while sighting not due to the shooter, that would be a big problem.. That said, I'm pretty sure that a LASER dot would make any less-than-steady sight alignment much more obvious, even when the LASER itself was NOT the cause. And, then tooo, a lack of rock-solid steadiness becomes much more obvious with more-distant targets.