Tuesday, June 5, 2018

Sighting in a handgun

A friend came over with a newly purchased handgun.

He had taken it shooting and thought it hit high and to the right.  He had been shooting at golf balls and dirt clods on a dirt berm.
36 grain ammo at a nominal 1260 fps out of a long gun.

Of course, he had not brought any ammo.  The first ammo we tried, a target ammo had two, back-to-back failures to extract.  Then we switched to a "High Velocity" .22 LR ammo and had much more robust extraction and ejection.

Yup.  High and to the right.  This is my shooting five shots at 10 paces, the range the "customer" does most of his tin-can shooting.  I was using the box of the pickup as a steady rest.  Good for vertical but a little embarrassing for horizontal.

Of course I read the manual AFTER sighting in his pistol.
The first adjustment had no effect.  The bottom of the screw head was floating above the top of the sight and turning the screw down had no effect.  The second adjustment did move the group, perhaps just a little lower than desired.

The third adjustment for vertical looked pretty good.  We were still seeing horizontal stringing.  Time to work on zeroing the horizontal.
The circled group is where we left the sights.
There comes a point where you are chasing noise.  We could have kept fiddling with the sights for hours and my shooting would have continued to degrade over time.

Without getting all mathy about it, the gun hit (median distance) 1.8" from the point-of-aim at ten paces as delivered from the factory, with my eyes, with my ammo.  After sighting in it hit 0.4" from the point-of-aim.  0.4" is well within minute of woodchuck or raccoon or reptiles with bad attitude.

And if his first shot does not anchor him, well, he has nine more for back-up.

The other thing is that he will "hit" differently than I do.  He will not be using a truck as a steady rest.  His eyes are different.  And he may find that ten paces is not where he does his precision shooting.  I didn't quibble because I believe anywhere between five paces and fifteen paces are fine distances to zero a handgun.  He is going to have to shoot the gun for a while and do any fine-tuning that is required.

According to one of the on-line ballistics calculators, given this gun and ammo (1020 out of a 5.5" barrel):
  • A five yard zero will result in a max rise above the line-of-sight of 4" and a second zero at 95 yards.  
  • A seven yard zero yields a 2" max rise and a second zero at 70 yards.  
  • A ten yard zero a max rise above the line-of-sight of 1" at 30 yards and a second zero at 50 yards.  
  • A fifteen yard zero yields a max rise of 0.2" above the line of sight and a second zero at 35 yards.
For the record, my buddy did run out and buy a couple of boxes of Federal ammo, lot number 1RE082.  That should keep him shooting for a few months.

1 comment:

  1. Yep, everybody IS different in their aim and how they shoot...


Readers who are willing to comment make this a better blog. Civil dialog is a valuable thing.