Point of aim - hits to left and low

[zupatun]

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

 

[SBruce]

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.

 

[Willys46]

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!

 

[ubettcha13]

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

 

[zupatun]

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

 

[zupatun]

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.

 

[bigngreen]

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.

 

[Bravo 4]

What Willys46 is trying to tell you is that every time you change loads/bullets/whatever you can expect a POI change. You can't zero your scope with one load and expect other loads to have the same POI. Some rifles may have the same POI with different loads but I would consider that an exception rather then the rule (opinion). As stated already, find your load first then fine tune your zero.

 

[zupatun]

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

The shot at 300yds 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

I found a glitch in my Shooter Android app for these loads--it has a zero height in it...which for dead nutz should be zero, I was putting my scope height in there. I originally had 3 MOA drop at 300 yds...but after putting in 0.0 at 100yds it was actually closer to 4.1MOA drop at 300. That would mean if I had dialed the other three clicks up I would be less than one MOA off in the vertical...still don't know why I'm left of center...my 10x scope has no parallax adjustment.

Matt

 

[zupatun]

What Willys46 is trying to tell you is that every time you change loads/bullets/whatever you can expect a POI change. You can't zero your scope with one load and expect other loads to have the same POI. Some rifles may have the same POI with different loads but I would consider that an exception rather then the rule (opinion). As stated already, find your load first then fine tune your zero.

POI in the vertical is a no brainer...POI change horizontally is buggin me...

 

[Bravo 4]

POI in the vertical is a no brainer...POI change horizontally is buggin me...

As stated earlier: Find the load you want then worry about zeroing. If you zero with one load and then switch to another, expect a shift in POI different from the load you originally zeroed with. It can be verticle, horizontal or all the above! It can be with the same grain bullet or even the exact same bullet over a different powder/primer combo. This may not always be the case, but you should expect it. I know all too many guys that sight in with one load then switch to another to hunt with, it can/will change POI. You need to check it, which you have done and found that the POI shifts left with that load from the original load's zero.
Example 1: My .308 AR has a different POI with the same zero from two different companies using the 175gr SMK with basically the same load. It is about 1moa verticle shift.
Example 2: My .338 EDGE has a 1/2moa horizontal and verticle shift by just changing the primer from FED215 to CCI 250.
Example 3: My Savage 7mm shoots my loads and a couple factory loads to same POI (the factory groups just open up more).

 

[SBruce]

Zupatun,Originally Posted by zupatun
POI in the vertical is a no brainer...POI change horizontally is buggin me...

If you're getting horizontal shift in POI with the same exact load under the same conditions but on different days (or even different targets) It could very well be parallax related.

Could also be a scope shifting issue. Internally or bases and/or rings.

Could also be a slight reticle or adjustment canting issue.

Maybe the combination of one or more of the above???

Last, but not least.......wind drift on target changes with temperature......back to the same conditions thing.

I am assuming here that the rifle and bedding is in good shape and your shooting form is good.

Just some ideas, hope to help. I know poi shift is a dreadful thing.

 

[Bravo 4]

Bruce,
In his original post it sounds like he is sighted in with one load the switching to a totally different one and impacting to the left. At least that's the way I (and the other that responded) took it.

 

[Willys46]

Bruce,
In his original post it sounds like he is sighted in with one load the switching to a totally different one and impacting to the left. At least that's the way I (and the other that responded) took it.

Bravo 4,
I'm with you. Sounds like he sighted in with one bullet and switched to a TOTALLY different load and bullet, and has no idea why the POI changed!

IF YOU CHANGE FROM ONE BULLET (weight or design) YOU CAN EXPECT A POI SHIFT!

IF YOU CHANGE FROM ONE LOAD TO ANOTHER (different powder, velocity) YOU CAN EXPECT A POI SHIFT!

When load development with the SAME bullet. I switched between two different powders and the POI shift was 3 MOA LEFT. The new load shot a nice .5 moa group just left!

When load development, do not even look at where the impact is..only concern your self with group size and velocity!

After you find a load that shoot good..then RE-ZERO the scope. Now you are sighted in for THAT LOAD! If you change ANYTHING, EXPECT a POI shift.