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Point of aim - hits to left and low

 
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  #1  
Old 11-03-2010, 01:52 PM
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Point of aim - hits to left and low

Don't know how to state this correctly, so here it goes...

I've been working on handloads for 308Win on Scirocco's (165), Interbonds (165's) and SST's (165's).

Yesterday I was doing seating depth testing on the SST's over 44.5gr Varget at 0.01, 0.05 and 0.09 off the lands. All my groups were to the left of center target.

I get on target with Black Hills Match ammo 168grain SMK....this hits literally dead center at 100 yards fouled cold bore shot, almost every time. My son shoots this dead center almost every time. Groups are in the 0.75moa range.

Here's a pic of my target from yesterday:


Other than the fact I can't reload worth a hoot, the groups are all to the left. Best group is 0.78 MOA but it is also about 0.6MOA to the left at 100 yds.

Is this an issue with my sight picture or parallax with me looking through the scope at 10X (Nikon Monarch 2.5-10x)?

Here's a pic of a gong I had set up at 300 yards...same thing...shot is 2.75" to the left of center point of aim...or about 0.9MOA to the left...wind was at 0deg (from behind me) gusting to 10-15mph, but at the time it was still. I only had time for the one shot, but I was relaxed and it was calm...

The shot is also 4.5" low...or 1.5MOA low...I chrono'd the Black Hills 168 Match ammo earlier that morning so I should have been dead nutz on (I was exactly at 300 yards as determined by the Leica) target...Shooter (Android) said 13 clicks up and that's what I dialed. Looks like it needed six more clicks up to be on...but if my groups are 0.75MOA I probably only need 4 up to scatter around center target (is this correct?).



Any feedback or suggestions/comments are welcome.

Matt
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  #2  
Old 11-03-2010, 03:01 PM
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Re: Point of aim - hits to left and low

Matt,

My advice would be:

Don't worry about it shooting left until you get your load developed and picked out. Once you've decided on the proper load (use the BH stuff as a baseline, try to get consistently better accuracy and velocity than you're getting with it) then it's a simple matter to move the scope adjustments to exactly where they need to be. 1" left at 100 is probably pretty close to 3" left at 300.
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  #3  
Old 11-03-2010, 11:21 PM
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Re: Point of aim - hits to left and low

Each bullet weight and design will impact at a different place. Even if it's the same weight bullet it has different harmonics and flight characteristics that make it hit different points. Heck a 175 serria match king and a 175 nosler custom competion (they look almost identical) have a different impact point in my gun.

Like what was said before, when load development do not worry about bullet impact, you looking for groups. When you settle on a load then rezero and your done!
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  #4  
Old 11-05-2010, 11:22 AM
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Join Date: Aug 2010
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Re: Point of aim - hits to left and low

Check your bedding. If you have already pillar bedded your action check the torque of your action screws. Start low and work up. If you see any change keep going till it goes bad. Then remove the action and return to where it was best.
If you have not pillar bedded your action either diy or have it done. Check your scope mounts lap in the rings if it was not done. Something is wrong. If these procedures don't do anything have the barrel borescoped.
For your loads eliminate as many variables as you can. Sort cases by weight. Use one brand of brass I use mostly winchester but have had good groups but not longevity with hornady cases. Lapua is above my pay scale as is norma. Weigh the bullets in some brands I've seen =+3 grns in a box of 50. If your not a proficent group shooter have someone that is help you.
Best of luck
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  #5  
Old 11-05-2010, 12:50 PM
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Re: Point of aim - hits to left and low

Bedding shouldn't be an issue. Torque on the action screws is at 40in/lb...on the lower end. I haven't done a test to see how/if it affects point of impact yet. I just notice that when I swap to Black Hills the impact point is dead center, not to the left.

Lapua brass for the above seating depth test...

Matt
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  #6  
Old 11-12-2010, 11:26 AM
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Re: Point of aim - hits to left and low

Shot more groups with the Black Hills 168 grain Match ammo and with my current pet load, virgin
308 Lapua Brass, 44.5gr of Varget 165 SST loaded 0.09 off the lands at 2.766 OAL.

First two groups of the handloads were 0.8 MOA to the left of center target--readjusted the turret to bring the next group dead center. Average of three, three shot groups was 0.8 MOA with virgin brass and Federal 210M primers...

The Black Hills Match rounds are averaging a little over 1 MOA currently at 100 yards. All the stringing is horizontal on both sets of rounds...

The veritcal dispersion of all the groups I shot yesterday was around 0.4MOA. It was somewhat gusty at 100 yards (my LR land is in the middle of muzzleloader season and I don't want to be messing up someone's hunt), but I don't think that's a huge contributor. I had 14 shots total with the handload - getting on target after cleaning and I let my son shoot some rounds as well--that were recorded by the Chrono. My ES is 11 and average is 2726 I had an extreme spread of 40fps because one shot was around 2690fps...without this shot the ES is 22...

I try to emulate Darryl Holland's (Originially typed Sean Carlock--my bad memory...) video on sight picture and keeping my cheek weld in the same spot. Also I had a very stable platform so I'm wondering if my 2.5-10 scope has any issues with parallax at 100yds or not? I have had enought range time in the last two months and dry firing at home to say that I had literally no flinches yesterday when working on those three groups and the BH match groups...got relaxed very early in the process...it was almost effortless.

That said, the ammo seems to be working pretty well, but the groups are not what I expect...perhaps the shooter is still the problem--trigger control is good, cheek weld is okay, but what about my sight picture etc...do I just need better mag to get tighter groups? I eliminated most of my thump-thump jiggle from my heart and my breathing control seems much better as well...I think maybe I don't like my grip either...maybe I'm not as consistent here--maybe too relaxed? Gripping harder might help?

Sorry for the train of thought typing, just trying to get my thoughts on paper (electrons)...

Matt

will post pics when I'm back at the house.
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Last edited by zupatun; 11-12-2010 at 01:23 PM.
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  #7  
Old 11-12-2010, 12:08 PM
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Re: Point of aim - hits to left and low

Another suggestion, a little of topic but read and watch everything that you can find by Darrell Holland, really changed my shooting form and the repeatability of my whole set up. He has some excellent articles on LRH, read them they really are good and helped get my self under control so that the rifle can do it's thing.
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