Illusive zero'ing

[timelinex]

So I'm switching over from FGMM 175;s to Southwest 175's and I had trouble zero'ing at the range today. I'm making my zero at 100 yards, but it seems like its always moving around. I did 5-6 groups and couldn't duplicate the same POI. Each group would be .5-.75 MOA so thats pretty good for a factory savage and 175's, BUT the POI in each group is ever changing! One would be .5MOA too high, so I would adjust it .5MOA, then the next group might be .25 too high, then next too low. ETC....

The only thing I could come up with is parallax error, but I tried to look back and forth and it didn't seem like so.

The only other thing I could thing of to check is make sure my cheek weld is consistent. So what else could it be?

 

[Force_Multiplier]

Re: Illusive zero'ing

bad scope, loose rings/bases, your error...yada, yada... we need more info

 

[timelinex]

Re: Illusive zero'ing

Scope is a vortex 6.5-20x50 and rings/bases are tight(burris xtreme low and EGQ 20 MOA base). I don't THINK they are the problem as it performed fine at a shoot last weekend all the way out to 1050 yards. I'll upload and post the group pictures tmrw, maybe that will help. What more info do you need?

I'm guessing its a cheek wled/parallax issue, but just wanted to confirm and see if there are other ideas.

 

[SmokinAce]

Re: Illusive zero'ing

Yea more info is needed but I ran into the same issue and it came down to the scope base not being tight since the installer forgot the locktite. Again thought it could be 1 of 100 issues. So more info would be nice.

 

[mouse07410]

Re: Illusive zero'ing

Is everything (base->receiver, rings->base, rings->scope) torqued properly? I assume you set parallax correctly - because if you don't then all bets are off.

Because I never use Loctite on the base (always torque it to specs) - and never had an issue like described. Same scope BTW, and it performed greatly in both shooting and milling the targets (turrets tracked perfectly).

Still the likeliest cause (no offense meant - and I don't know your skills/proficiency level) is the shooter.

 

[timelinex]

Re: Illusive zero'ing

I really don't think its scope/rings/bases since they float up and down and not just one way. Scope walk would go just one way. As I said, with parallax, I did check to make sure it didn't SEEM like there was any parallax. There was ALOT of mirage yesterday though(105 degree weather).

The other difference between the groups is they were all taken within a 2 hour span of time , where it went from low 90's to low 100's. But I don't see it making that much of a difference at 100 yards, and it wouldn't bring it up and then back down....

So here's a picture of what I meant

The first group is at the middle right. So Ill walk you through the groups.
1)This was at the zero I had for FGMM
2)The last group was a little over .5 MOA up, so I set my turrets .5MOA down. Already doesn't make sense that these were .75 lower than the first.
3)I tried just one shot at .25 Down, correcting the last gtroup that was .25 lower. It hit center, so I moved on to next group
4)I tried a group at .25 Down and it wasn't any different than grup #2 that was .5 down!
5)I tried going back to the initial zero, and it was perfect, even though the first one was .5 up at the zero.
I would have been happy here, but I had one more group after this that wasn't in the picture, where right after I tried a group again
6)I tried at the zero again, that I just got perfectly in the center and it was .5MOA to high, just like the first time I tried this zero!


I deffinitly am not saying skill is ruled out, but I didn;t have this problem before, and this is 100 yards not 200+.....

 

[KNIGHT11B4]

Re: Illusive zero'ing

The error could be on the shooter due to the conditions. Im not suggesting that temp or other environmental factors have moved your groups but rather that they made the shooter uncomfortable and thus proper fundamentals were not executed perfectly.

If mechanical problems are tested and found to not be a problem this is where I would look.

Chasing a tiny zero dot in heavy mirage can drive a person crazy. Try backing down the mag on your optic to help battle this.

If you are uncomfortable because it was so hot and dealing with sweat, it very well could have effected your shooting. As you said, not having proper cheek weld.

Is is possible to have another shooter pull off a few rounds?

 

[timelinex]

Re: Illusive zero'ing

Yea I guess Ill just have to try again.

My other quick question is, if you take a look at my groups, you can see that it's always two on the left that are almost in the same whole and then a third that takes it from .2MOA to .7MOA . When I do 5 shot groups, its the same thing, with 3-4 all in the same area and 1-2 out of the group. Is it more likely that its ME pulling 30% of the shots, or the ammo(its not hand rolled, but factory match ammo).

 

[KNIGHT11B4]

Re: Illusive zero'ing

That third shot you are talking about is more of a horizontal movement, I would bet trigger press or even sight picture. In general it would be more or a vertical shift if it was the ammo.

That SW ammo is outstanding, that I know to be a fact.

It may have already been stated but: What rifle?

 

[timelinex]

Re: Illusive zero'ing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KNIGHT11B4</div><div class="ubbcode-body">That third shot you are talking about is more of a horizontal movement, I would bet trigger press or even sight picture. In general it would be more or a vertical shift if it was the ammo.

That SW ammo is outstanding, that I know to be a fact.

It may have already been stated but: What rifle? </div></div>
Thats a good point, I'll just have to pay more attention to it.

It's a factory Savage 10 FCP-K

 

[notquiteright]

Re: Illusive zero'ing

It would be soooo much easier to divine this if the shooter was real time. The .25 moa shift can be so many little things in the verticle.

Bipod/sock guys do this when they either have inconsistent breathing or try and muscle the sock in position rather than build the solid base each time.

If you put a few rounds on one side of the dot and then one or more on the other side you could be, without thinking, adjusting to hit center.

Did you keep your face on the stock the entire time? I mean no break until ALL groups were shot?

Did your shoulder tighten? Did you rush the shot? Did you stop and wipe your face?

Difficult to judge unless right there beside you, watching your finger, feeling your shoulder, whispering sweet nothings in your ear..... ahhhh that might be just me

 

[timelinex]

Re: Illusive zero'ing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: notquiteright</div><div class="ubbcode-body">It would be soooo much easier to divine this if the shooter was real time. The .25 moa shift can be so many little things in the verticle.

Bipod/sock guys do this when they either have inconsistent breathing or try and muscle the sock in position rather than build the solid base each time.

If you put a few rounds on one side of the dot and then one or more on the other side you could be, without thinking, adjusting to hit center.

Did you keep your face on the stock the entire time? I mean no break until ALL groups were shot?

Did your shoulder tighten? Did you rush the shot? Did you stop and wipe your face?

Difficult to judge unless right there beside you, watching your finger, feeling your shoulder, whispering sweet nothings in your ear..... ahhhh that might be just me

</div></div>

Yea I know what your saying. I know that most things can't be accuratly diagnosed without actually seeing it, and even then its not always apparant. All the different ideas thrown out just help me remember what to look for next time...

 

[Sterling Shooter]

Re: Illusive zero'ing

Single load. Rebuild the position for each shot. If possible, use a sandbag support, with the non-firing hand placed between hand-guard and sandbag. Mental management should be: sight alignment, NPA adjust, focus on sight, smooth trigger control, and follow-through. Call your shots. Shoot a 20 round string.

 

[timelinex]

Re: Illusive zero'ing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sterling Shooter</div><div class="ubbcode-body">Single load. Rebuild the position for each shot. If possible, use a sandbag support, with the non-firing hand placed between hand-guard and sandbag. Mental management should be: sight alignment, NPA adjust, focus on sight, smooth trigger control, and follow-through. Call your shots. Shoot a 20 round string. </div></div>
Will do exactly this, thanks.

 

[jimdvt]

Re: Illusive zero'ing

I remember reading a good article about groups some time ago. The sum of it was you need at least 7 shot groups before you can start gauging the statistical accuracy, 10 shots is better. I couldn't find that article but I did find this link: http://www.longrangehunting.com/articles/accurate-rifle-groups-1.php

I assume you didn't have this problem before you changed ammo and nothing has changed with your rig. I would shoot a 10 shot group of both types of ammo as you really can't see anything with three shots. If the Fed gives you a nice consistent group and the SW is a shotgun pattern then your rifle doesn't like that load. Obviously take your time, pay attention to the fundamentals, and call your shots. Over a 10 shot string you're likely to have something happen you didn't like that's directly attributable to you, so just note those occurrences. Good luck.