After Bore Sighting Rifle Scope

lash

Swamp Rat
Sep 28, 2012
3,080
774
113
59
Central Florida
#2
How and with what did you bore sight the rifle? At what range are you zeroing. There is no 'normal" as all depends upon the technique used and the ability of the equipment/person doing the bore sighting. And stop calling them clicks. Talk in numbers.

What is your specific situation and details? Maybe we can provide an answer.

If it helps, this is my process:
  • At 100 yards, I pull the bolt and sight down the tube (barrel) at a large target (!2" diameter or so) with a small bull (1-1/2" or less). I do this with the rifle on bags, at least the rear if not both front and rear.
  • Then, when I have the target in the center of the rifle bore (bore sighted), I look through the scope, being careful not to move the rifle in any way. I measure the distance in my scope from the center of the target's bulls-eye to the cross-hairs of the scope. How many mils/moa up/down and how many mils/moa left or right am I from the center?
  • Then I adjust the scope the correct amount up/down and left/right so that when I look down the barrel and look through the scope I see the same bulls-eye center.
  • At that point, I will replace the bolt and fire one shot, Two if I call a pulled shot for some reason.
  • Then I measure how far from exact bulls-eye center my impacts are from my point of aim and adjust point of aim accordingly. Usually this is within 0.5 mils or 1.5 moa or less
  • Another shot (or two as needed) and final adjustment if needed.
  • Then I shoot 3-5 rounds to see if it stays consistent measuring any introduced shooter error in the previous adjustments.
Does that begin to answer your question?
 
Dec 16, 2011
295
1
18
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Sunrise, Fl
#3
after mounting the scope, I used a laser in the muzzle (using the proper caliber attachments)and the target that came with the laser at 25 feet.
(schmidt & bender 5-25x56 on a AI/AT which has a 20 moa rail.)
The issue is after adjusting the laser to the 25" target I needed to turn up 8.5 mils of elevation from the factory settings.
this is what is causing me concerns
 

lash

Swamp Rat
Sep 28, 2012
3,080
774
113
59
Central Florida
#4
That does not sound right. So, after adjusting your scope zero so that the cross hairs are on the target at the same place the laser is, you are dialed UP 8.5 mils. How many mils of elevation do you have left above your new zero?
 
May 27, 2014
658
285
63
32.752325 -79.867804
#5
I never bore sight, but if your scope is at it's mechanical/default zero is mounted properly and you have a 20 MOA base you would be pretty high at 100yds and have to come down for a 100yd zero. Think about like this if you have a 20 MOA base you would need to dial 20MOA down just to start at what you would if you had a 0 MOA base.
 

Sig Marine

Sergeant - USMC 1968-1970
Dec 29, 2013
350
21
18
So Cal
#6
How and with what did you bore sight the rifle? At what range are you zeroing. There is no 'normal" as all depends upon the technique used and the ability of the equipment/person doing the bore sighting. And stop calling them clicks. Talk in numbers.

What is your specific situation and details? Maybe we can provide an answer.

If it helps, this is my process:
  • At 100 yards, I pull the bolt and sight down the tube (barrel) at a large target (!2" diameter or so) with a small bull (1-1/2" or less). I do this with the rifle on bags, at least the rear if not both front and rear.
  • Then, when I have the target in the center of the rifle bore (bore sighted), I look through the scope, being careful not to move the rifle in any way. I measure the distance in my scope from the center of the target's bulls-eye to the cross-hairs of the scope. How many mils/moa up/down and how many mils/moa left or right am I from the center?
  • Then I adjust the scope the correct amount up/down and left/right so that when I look down the barrel and look through the scope I see the same bulls-eye center.
  • At that point, I will replace the bolt and fire one shot, Two if I call a pulled shot for some reason.
  • Then I measure how far from exact bulls-eye center my impacts are from my point of aim and adjust point of aim accordingly. Usually this is within 0.5 mils or 1.5 moa or less
  • Another shot (or two as needed) and final adjustment if needed.
  • Then I shoot 3-5 rounds to see if it stays consistent measuring any introduced shooter error in the previous adjustments.
Does that begin to answer your question?
Winner, winner, chicken dinner! It's as easy as it sounds.
 
Jan 23, 2013
134
3
18
33
AZ
#7
Usually, after using laser bore sighters, a shooter must make an extreme down elevation change. As in off the paper at 100 yards. As in laser bore sighters are worthless junk that save neither time nor ammunition.

Strange it would be the other way around, but like I said... they are junk. Eyeballing it gets you a lot closer.
 
Feb 13, 2017
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#8
If scope is mechanically centered from the factory, with a 20 MOA base, you would need to adjust your elevation by 20 MOA or 5.82 MIL just to get your scope re-centered. Then any additional adustment is to actually get your scope zeroed with your rifle at a given distance. So really, if you're seeing 8.5 mils of adjustment, it's actually only 3.3 MIL, which seems just fine. But it depends on the scope and rifle. With a high-quality scope, rifle, and rings, sometimes one only needs a few 10ths of a MIL. For my rifle, once I dialed down 5.82 MIL from mechanical center to compensate for my 20 MOA rail, I only need 0.4 MIL of adjustment in elevation and 0.2 MIL in windage to get my rifle zeroed at 100 yards.
 
#9
Depending on what your scope over bore height is it is not uncommon to have to use use 5-8mils up for a 8yd shot(24ft). For example- with a 1.95" scope over bore my 24ft (8yd) hold is 5.4mils. With a 2.5" I am at 7mils.

A couple other things to consider are that guns are not perfectly straight. You have a number of tolerances with in a bolt action rifle. You have bore curvature, tolerance in the action face, tolerance in the barrel tenon,threads, and shoulder,etc.......


All that being said......I am not a fan of bore sighters either. Especially when sighting through the bore costs nothing and seems to work much better.

Scott




 
Dec 16, 2011
295
1
18
52
Sunrise, Fl
#10
Thanks for all the info! I made it to the range today and the crappy lase bore sighter was very close.It was .2 mils off elevation (now 8.7mils) but the windage was a bit more off.
3 shots to zero the scope. I am still a little confused why it took 8.7mils of elevation though
 

Tucker301

Groundskeeper
Staff member
Feb 13, 2015
6,797
2,538
113
Southern VA
#14
Thanks for all the info! I made it to the range today and the crappy lase bore sighter was very close.It was .2 mils off elevation (now 8.7mils) but the windage was a bit more off.
3 shots to zero the scope. I am still a little confused why it took 8.7mils of elevation though
At 100 yards your POI and POA are going to cross each other like this, due to the 20 MOA tilt. They will meet again when your bullet travels far enough to drop 20 MOA from the effects of gravity.

 
Feb 15, 2017
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#16
Here's what the manual for the S&B 5-25 says. "In order to make the elevation adjustment range usable in its full extent it is necessary to preset the reticle of the PMII scopes out of the center already at the Schmidt & Bender factory (see picture 3). As a consequence the gunsmith is obliged to consider the preset position of the reticle in the elevation range when mounting the scope to the firearm (see picture 4). With this setup the full elevation range is usable in one direction allowing to shoot at distances up to 2000m depending on the used calibre and scope type." They don't come mechanically centered. I have a 20 moa rail on my rifle, and I had to come up 7.2 mils to zero mine.
 
Dec 16, 2011
295
1
18
52
Sunrise, Fl
#19
Here's what the manual for the S&B 5-25 says. "In order to make the elevation adjustment range usable in its full extent it is necessary to preset the reticle of the PMII scopes out of the center already at the Schmidt & Bender factory (see picture 3). As a consequence the gunsmith is obliged to consider the preset position of the reticle in the elevation range when mounting the scope to the firearm (see picture 4). With this setup the full elevation range is usable in one direction allowing to shoot at distances up to 2000m depending on the used calibre and scope type." They don't come mechanically centered. I have a 20 moa rail on my rifle, and I had to come up 7.2 mils to zero mine.
thanks, I didn't see that statement in the manual.
7.2 mils - 8.7 mils, now I am not as concerned. By the way what caliber are you running for 7.2 mils initial setup?
 

scudzuki

Gunny Sergeant
Jul 1, 2012
2,052
64
48
52
Philadelphia suburbs
#22
I use a laser boresighter all the time, which usually gets me within 6" at 100 yards.
When I'm boresighting on a wall in my house (let's say 30' away) I set the laser dot 1.5" below the reticle center.
 
Feb 15, 2017
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#23
thanks, I didn't see that statement in the manual.
7.2 mils - 8.7 mils, now I am not as concerned. By the way what caliber are you running for 7.2 mils initial setup?
I am shooting factory Hornady .308 Win. 168gr AMAX TAP. This is the issued load for my work rifle. It chronographs at 2715 fps from a 20" barrel. I have 22 mils of up elevation remaining on my turret after zeroing. That will get me to a calculated 1400+ yards, according to AB. I've only verified to 1000.
 
Apr 27, 2017
6
0
1
#28
If I am visually boresighting at 25yds with a 20MOA base, I usually center the target in the rifle bore and align the scope cross hairs 4-6" lower. This will usually get me on the paper at 100yds.
 

Nik H

Constantly Learning
Jan 22, 2014
3,391
1,108
113
Rhode Island
#29
Hopefully no one takes these suggestions seriously
It seems that anyone with a computer is a self professed "expert". I have never seen more mystique applied to a simple procedure. I never boresight. Never have to. You say that and people look at you with disbelief and then argue.

I am always amazed at how many bring the scope and rifle to a gunsmith so he can "properly' mount it for them
 

spife7980

Full Member
Feb 10, 2017
3,520
580
113
TX
#30
It seems that anyone with a computer is a self professed "expert". I have never seen more mystique applied to a simple procedure. I never boresight. Never have to. You say that and people look at you with disbelief and then argue.

I am always amazed at how many bring the scope and rifle to a gunsmith so he can "properly' mount it for them
Not sure why you quoted my post as I wasnt addressing anything to do with bore sighting but instead alerting the unsuspecting to the shill trying to trick people into clicking his amazon links for free money and bad advice.
 

Thunderhorse

Sergeant of the Hide
Jan 31, 2018
201
63
28
Central MO
#34
I always looked through the barrel at a doorknob or something down the hallway of my house and dialed the reticle onto that; its always been enough to get me on paper at 100 yds sighting in. Never felt the need to buy a boresight or stick a poorly machined aluminum shaft in my muzzle
 
Feb 13, 2017
339
47
28
#35
It seems that anyone with a computer is a self professed "expert". I have never seen more mystique applied to a simple procedure. I never boresight. Never have to. You say that and people look at you with disbelief and then argue.

I am always amazed at how many bring the scope and rifle to a gunsmith so he can "properly' mount it for them
Agreed.

I've never had to boresight or sight-in at 25 yards or 50 yards or whatever first "just to get on paper."

I set my scope to mechanical center (compensating for a canted rail) and go straight to 100 yards. I'm usually only a few clicks off in any given direction. Easy. Takes all of 5 minutes.
 
Likes: Nik H
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