Sight in technique/opinion

[357MAGNOLE]

I had a quick sight in/pattern session last week with the new 870 shooting Federal HW #7's.  After sighting in (Scope) with some comparable loads to get me on target I took a couple shots from 25 and 40 yards.The 25 yard shot grouped a tad low and right but obviously an acceptable shot.  The 40 yard pattern grouped a little high and left....

Now, I can't honestly say whether or not I pulled it a tad on one shot, if the wind gusted slightly, or any other number of possible issues (hopefully these loads aren't known for moving around).  But I am looking to do my fine tuning this week and get it completely and as perfectly as possible dialed in.  If for whatever reason I end up with a bird making himself available at 10-15 yards I want confidence I am not going to miss. Same goes for further shots.

Some time this week I am going to shoot from a bench at 12.5 yards at a quarter sized orange sticker until I can completely blow it out.  Hopefully it only takes 1-2 shots.  Then move it back to 25 to verify center, then 40.  I hope it goes smoothly and I don't experience any pattern shifting issues like I did with the longbeard XR's before. That was a certified PITA.

So have any of you used this method (1/4" MOA adjustment scope) or a similar method before or something completely different?

Pictures below for reference to POA/POI.  If you feel like I am being picky and should just roll with what I have and not waste time and shells feel free to say. I have been thinking it was solid, but in the back of my mind I keep wondering about why it was low/right on one shot and high/left on the other.


25


40

[dirt road ninja]

You're fine, but if shooting a few more makes you feel better than by all means go for it. Confidence is 90% of the game.

[357MAGNOLE]

You're fine, but if shooting a few more makes you feel better than by all means go for it. Confidence is 90% of the game.

Kind of my thoughts. I know for a fact that 25 yard shot conditions where perfect and I did not pull it. So I just went full nerd in my garage and did some science.  Determined my best shot density was precisely 1" to the right and 1/2" low.

So using my MOA adjustments, for a 25 yard zero I went 16 clicks left, 8 clicks up.

Will head out to the range this week and verify it is dialed in at 12.5, 25, and hopefully solid at 40.

Its killing me not knowing exactly what caused the poa/poi shift on that 40 yard shot. 

[sixbird]

I wouldn't discount a scope issue if you didn't pull it. Not saying that's what it is but that would be something I'd look at if you suspect something isn't right. If the shot is going in one direction, it should continue doing the same thing, all things equal.
Were you shooting from a bench or rest of some kind?
That said, it looks like you get him in the noggin' with either of those shots...They're not that far off...
Maybe, like you say, a little target time will confirm that you're o.k. I sometimes drive myself nuts for no good reason and find that all the things I built up in my mind were just in my mind...