Wear and changing point of impact [Archive] - Glock Talk


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09-01-2011, 17:58
I have noticed that my groups have moved to the left a bit over the 12 and 9 years I've been shooting my G19 and G21 respectively. The groups remain good and continue to surprise my shooting buddies who are not that familiar with Glocks. Other than the probably 10,000 rounds (possibly more) through both of them, no factors have been changed other than new recoil springs and striker springs (factory spec.). The guns remain in excellent condition and continue to function perfectly as always.

Has anyone else noticed a drift in point of impact after lots of rounds? I use the same shooting range, ammo (reloads and factory) and paper targets and my vision remains good, so I suspect normal wear has caused a slight shift. I ordered the MGW sight adjustment tool and will be making a slight adjustment to the rear sights of both pistols to bring them back to center.

Just wondered if anyone else experienced something like this. Thank you for your thoughts on this.

09-01-2011, 18:16
Has anyone else noticed a drift in point of impact after lots of rounds?

For sure.. I also start getting light headed and my vision starts to get blurry.:drinkie:

09-02-2011, 18:50
Maybe there's some habit you have that is moving the rear sight to the left, possibly when cleaning or some other activity that is bumping the rear.

09-04-2011, 05:41
Hamerhead, the rear sights are in the same position as always...exactly in the center of the dovetail notch. They haven't moved. I really suspect wear has caused this since both guns have been affected.

It's really a minor problem and easily corrected, but I was just wondering if anyone else had this experience after thousands of rounds went through their gun.

09-04-2011, 10:15
I don't see how that would be possible unless the barrel lock up is wearing significantly at the front or rear, and then it would have to wear on one side only. Highly unlikely IMO.

09-04-2011, 19:24
I have noticed that my groups have moved to the left a bit over the 12 and 9 years I've been shooting my G19 and G21 respectively. Has anyone else noticed a drift in point of impact after lots of rounds?

Nope, and I have a Gen 1, G-17, with over 100000 rounds through it and the point of impact hasn't moved.

To be honest, I would suspect you have developed a change somewhere i.e., trigger control, grip, sight alignment/sight picture, etc. I would suggest having someone else shoot the gun and see what happens.

I know your thinking that it can't be you because your groups are so tight. I have seen it many times where a shooter will ask to have their sights adjusted based on a good group that's left or right. Yet when I (or another instructor) take their gun and shoot it, the rounds go right where they should.

All that said, there's nothing wrong with adjusting your sights to compensate.

09-07-2011, 11:23
Thanks for the input. I got my MGW sight adjuster tool yesterday and will take it to the range with my Glocks. You could be right about possible changes in my shooting technique but I honestly can't think of a single thing...I've been shooting pistols for 39 years. The points of impact from my Colt Series '70 Gov't. model and Colt Officer's ACP haven't changed despite a large number of rounds through both of them. On the other hand I realize the Glocks have a different trigger and general feel, but I have been shooting the two Glocks since 1999 and 2002 respectively using the same grip and stance.

I will bench rest the Glocks to get a more precise picture of the issue before moving the rear sights slightly to the right. Elevation still remains perfect.

09-08-2011, 19:07
Yeah, that's a head scratcher, let us know what you come up with.

09-12-2011, 18:00
Well, I went to the range today and very carefully shot the G19 and G21 from a bench rest at 10 yards. I used a home-made aperture that clips onto my eyeglasses and provides clarity to front and rear sights as well as the target. I wear tri-focals, so there's no other way to get all three items in good focus using the open sights.

Both guns produced tight groups right in the center of the targets. No deviation to one side or the other. Apparently the point of impact has NOT changed after all!

From a standing position, using the "for distance" (upper) portion of my eyeglasses, I shot decent groups all centered around the middle of the target. In this case the sights were blurry and the target was clear. Nevertheless there was no deviation to one side or the other with the groups.

The thought occurred to me...this summer was really hot and humid and I had been sweating uncomfortably from June through August at the range, including my hands (yes, N.Y. can turn into a jungle in the summer). I did not sweat today and had a nice firm grip on the guns due to the pleasantly low humidity and temperature this morning.

With this in mind I will pay attention to the weather conditions to see if there is a pattern to this "drifting" that may be related to skin moisture (I have second generation guns and might benefit from grip sleeves to prevent twisting in the hand.)

You guys were right after all about it being me and not the guns, even after years of shooting. Thanks for your input.