GlockTalk.com
Home Forums Classifieds Blogs Today's Posts Search Social Groups



  
SIGN-UP
Notices

Glock Talk
Welcome To The Glock Talk Forums.

 
  
 
 
Thread Tools Display Modes
Old 01-03-2011, 18:20   #141
ADK_40GLKr
Senior Member
 
ADK_40GLKr's Avatar
 
Join Date: Nov 2010
Location: RFD NY Adks
Posts: 2,153
Blog Entries: 2
Sighting in the picture.

I'm just a newbie with very little handgun experience, but I'm a former geometry teacher.

I think we can all see that #1 and #2 are using the same sight references (the tops of the front and rear sights) so the line of sight raises from #1 to #2. For the shot in #1 and the shot in #2 to hit in the same place, one of the sights is going to have to be adjusted, right?

I'm told people use "Pumpkin on a post" (#1) for competetion, so they get their pistols sighted in to work that way (at a limited range, I might add.) Also the size of the "pumpkin" will have a lot to do with where the bullet hits it, correct?

#2 & #3 are using different reference points, and the respective lines of sight are parallel 1/16" apart. Can you adjust your sight for that difference in elevation even at 7 feet? You just compensate based on your experience and practice, right again?

My point? A choice between 2 & 3 should be a matter of personal preference, while choosing #1 would be more practical if you always use a specific target at a specific range.

Now, before any of you decide to flame me if you disagree, think about the ballistics and geometry. I'm not saying one sight picture is right and the other wrong, but this is how it works. If a ballistics "expert" out there understands this different than I seemed to describe it, let me know.

But it would seem to me that you'd have to adjust your sights for either #1 or (#2 & 3) and you couldn't have it both ways.....

(If I've erred in this, it's more likely to be my explanation than my understanding, but hey, there may be some stinkin' thinkin' involved as well!)
__________________
There's a fundamental flaw in a system that passes laws that put an onerous burden on law-abiding citizens, but fails to prosecute the criminals who break those laws.
ADK_40GLKr is offline  
Old 01-03-2011, 18:50   #142
ADK_40GLKr
Senior Member
 
ADK_40GLKr's Avatar
 
Join Date: Nov 2010
Location: RFD NY Adks
Posts: 2,153
Blog Entries: 2
Just noticed Butch's and Bentbiker's posts above. I was trying to say the same thing, almost.

But in response to the arc rising, that's only because the line of sight is angled down to intersect with the bullet's path at a specific range.

Physics 101: Assume a perfectly horizontal surface. (Not the curvature of the earth.)

Fire a projectile parallel to that surface and drop one from the same spot at the same instant. Regardless of the forward momentum of the first, gravity works on them both the same. They will hit the "ground" at exactly the same time. The only way the bullet will ever rise, is if the bore axis is angled upward. The fired bullet begins dropping (from it's initial line of travel) at the same speed as the one that was dropped. (It's just that it's also travelling forward as well.)

"Bore sighting" adjusts the sights so that the line of sight intersects the bore axis at a specific distance.
"Sighting-in" adjusts the sights so that the line of sight intersects the bullet's anticipated path (trajectory) at a specific distance. (See Butch's diagram.)

(And YES, with 140-some previous posts, I've probably overlooked somebody's analysis that said the same thing - SORRY!)
__________________
There's a fundamental flaw in a system that passes laws that put an onerous burden on law-abiding citizens, but fails to prosecute the criminals who break those laws.
ADK_40GLKr is offline  

 
  
 

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump




All times are GMT -6. The time now is 00:03.




Homepage
FAQ
Forums
Calendar
Advertise
Gallery
GT Wiki
GT Blogs
Social Groups
Classifieds


Users Currently Online: 952
192 Members
760 Guests

Most users ever online: 2,244
Nov 11, 2013 at 16:42