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Inaccurate adjustments?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2011 at 06:17
Michael Riley View Drop Down
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I recently purchased a Nitrex TR2 3-15X42 and put it on a Marlin 880SQ .22lr.  I got this scope so that I could set my rifle up to shoot out to 200 yards and be able to quickly adjust back down to 50 yards where the majority of my shooting is done and I really liked the pop up turrets for that.  Anyways, I've only shot at 200 yards 2 times since I mounted the scope.  When I went out to 100 yards my group was 9 inches low but it only took 8moa of adjustment to dial it on.  Then when moving out to 200 yards I started at 27.5 MOA based off of a chart I made from JBM ballistics and I was shooting about 5 inches high.  I dialed it down 2.5 MOA and my group ended up being almost 5 inches below the X ring.  I adjusted it 2 more times and in the end I was shooting 4-5 inches high.  I couldn't get it dialed on.  Are my adjustments off or do you think my problems may be caused from just not having any experience shooting this far with a .22lr?  I've shot out to 600 with my .22-250 so I have a little medium-long range shooting but not with the .22lr.  I haven't done a box test yet but I plan to at 50 yards the next chance I get.  I just wanted to get some opinions on what my issue is most likely to be.  The adjustments appear to be repeatable so far and the scope goes back to its 50 yard zero every time but I don't think the clicks are true 1/4".  I'm just not sure!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2011 at 06:18
Michael Riley View Drop Down
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Also, I'm using CCI 40 grain sub sonics if that info is needed.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2011 at 09:42
Poodleshooter1 View Drop Down
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What's your group size at 200yds? It may be difficult to assess scope tracking if groups sizes are in the typical 4" or so I'd expect at 200yds with .22lr (even with decent ammo).


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2011 at 13:43
Shenko View Drop Down
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I just plugged some numbers in to a ballistics program to see if I could match yours. Some questions:

How high is your scope mounted?

Are you confident that the 100 and 200 yard distances are exactly that?

What numbers are you using for the BC and MV of your ammo?

When you dialed it down 2.5 MOA, how many clicks was that?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2011 at 05:21
Michael Riley View Drop Down
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Originally posted by Shenko Shenko wrote:

I just plugged some numbers in to a ballistics program to see if I could match yours. Some questions:

How high is your scope mounted?

Are you confident that the 100 and 200 yard distances are exactly that?

What numbers are you using for the BC and MV of your ammo?

When you dialed it down 2.5 MOA, how many clicks was that?
 
The scope is 1.75" high.
The distances were ranged to +- 1 yard of 100 and 200 with a Nikon 400 rangefinder.
I used a .125 BC (Nikon Spot on BC for CCI subs).
MV is 1050fps according to CCI but I haven't chrony'd it. 
When I dialed down 2.5 MOA I went 10 clicks.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2011 at 05:27
Michael Riley View Drop Down
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Originally posted by Poodleshooter1 Poodleshooter1 wrote:

What's your group size at 200yds? It may be difficult to assess scope tracking if groups sizes are in the typical 4" or so I'd expect at 200yds with .22lr (even with decent ammo).


 
I had two 4 shot groups that measured around 2.5" but the 5th shot on each one opened them to around 4-5 inches, then the rest of the groups were all ~4 - 5". 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2011 at 08:18
stickbow46 View Drop Down
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Check to make sure all the screws on the rings are tight.It seems very odd that this happens on the 5th rd.I use to have a savage in .308 that used to open up a tight group after 4-5 rds.Turns out the barrel use to over heat.I changed  to a bull barrel,end of problem,but I don't see thast hapening with a .22lr.
 
Also check the ring alignment to each other,you might have to lap the rings.Keep us updated.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2011 at 11:21
Shenko View Drop Down
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The only part of that, that seems out of line to me, is the group moved twice as much as it should have when the adjustments were made at 200 yards.
It sounds to me like more shooting at 50 or 100 yards is called for to sort things out.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2011 at 23:48
Michael Riley View Drop Down
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Originally posted by stickbow46 stickbow46 wrote:

Check to make sure all the screws on the rings are tight.It seems very odd that this happens on the 5th rd.I use to have a savage in .308 that used to open up a tight group after 4-5 rds.Turns out the barrel use to over heat.I changed  to a bull barrel,end of problem,but I don't see thast hapening with a .22lr.
 
Also check the ring alignment to each other,you might have to lap the rings.Keep us updated.
 
I shouldn't have said 5th round.  I'm not sure which round was the flyer in the groups, just that one of the 5 opened 2 of the goups way up.  I didn't have my spotting scope with me and didn't check the groups until after 5 shots each time. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/27/2011 at 08:02
Mike McDonald View Drop Down
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.22lr 40 grain moves about 2.2 to 2.4 horizontal moa per mile per hour of wind, and also moves about 1 vertical moa per mile per hour of wind at 200 yards.
 
At 100 yards it moves 1 horizontal moa per mile per hour and 0.5 vertical moa per mile per hour as a general rule of thumb for both distances.
 
If you were dialing and holding with the expectation that performance would be par with a centerfire then might that account for what you were experiencing?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/27/2011 at 22:03
Michael Riley View Drop Down
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Originally posted by Mike McDonald Mike McDonald wrote:

.22lr 40 grain moves about 2.2 to 2.4 horizontal moa per mile per hour of wind, and also moves about 1 vertical moa per mile per hour of wind at 200 yards.
 
At 100 yards it moves 1 horizontal moa per mile per hour and 0.5 vertical moa per mile per hour as a general rule of thumb for both distances.
 
If you were dialing and holding with the expectation that performance would be par with a centerfire then might that account for what you were experiencing?
 
At 200 yards I dialed in 2MOA for windage and the groups were relatively centered just high and low.  I was not aware of there being vertical drift due to wind.  I don't have a wind meter so i'm not positive how fast the wind was blowing but it was pretty light. It was blowing from the left and slightly towards me. 
 
One possible thing I just thought of is that at 200 yards my scope is nearing its max elevation adjustment range and when I sighted it in at 25 yards I had to adjust about 3 inches to the right to get it on.  Would that make the adjustments less accurate towards its max?  I believe it was adjusted 10MOA to the right of its center after the 2MOA adjustment to the left for the wind at 200. past its center.  But I'll have to double check it sometime.  Hope i'm making sense.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/28/2011 at 07:02
Mike McDonald View Drop Down
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Wind toward the shooter drops the bullet impact
Wind from a shooter raises the bullet impact
So you can see how the wind might play havoc with that little 40 grain low speed pill.
 
Even on a 1 inch tube scope, 5 moa total windage shouldn't really affect elevation adjusments.
Having said that; it is possible on some less orbust scopes that the erector spring is/becomes too weak to hold the erector assembly in a fixed position when at near max extension.
 
Just when you think you have it sorted out something else comes along Smile
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/28/2011 at 20:29
Michael Riley View Drop Down
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Makes sense.  Just not something that I thought about.  Thanks for the info and help.  I'll just have to go play around with it more and see if I can get it figured out.
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