Advice on working up Seating Depths

[mnorg]

I am fairly new to reloading for precision. I have a Savage 12BVSS in 223 and have just made it through my first can of powder. I am using 69g Sierra HPBT, CCI Benchrest Primers and Winchester 748 powder. My last bunch of handloads I worked up 20 rounds of each at .005, .010, .015 and .020 off of the lands to see which my rifle prefers. The advice was to fire 4 5 shot groups at 200 yards. 200 yards more apt to show a difference and yet not be too affected by enviromental conditions. Each group had a flyer which was probably my fault, so I counted the 4 best and recorded the following.

Seating .005 - .890", 1.550", .603", 1.795" Avg=1.209
Seating .010 - 1.477", 1.476", 1.226", 1.415" Avg=1.399
Seating .015 - .976", 1.276", 1.333", .947" Avg=1.133
Seating .020 - 1.672", .446", 2.533", .685" Avg=1.334

I am more puzzled now because my .005" and .020" groupings had 2 good groupings and 2 bad groupings. My middle two loads were more consistent but not as good as my best groupings. The conditions on the day I did the testing were good but not ideal. I loaded up another batch of .005 - .030 off the lands and am going to try again to see if there are any trends. Any advice before I head out to try again? should I drop back to 100 yards to eliminate possible windage variations that might skew my groupings?

 

[martinbns]

The only probem with testing a 223 at 200 yards is wind drift. If there is any inconsistency to the wind at all your groups will suffer. Ive never loaded 69 gr bullets, mine shoots 55 gre Vmax bulelts over Varget and H335 best, using federal small rifle match primers. I find the small bullets and small case hard to play with given my chubby fingers so I just load to SAAMI depth, the H335 load is good enough to break clays at 500 metres and the broken pieces of clays at 300 mtrs.

 

[sunray]

Consistent groups are far more important than the best group. Consistency gives you a place to start fine tuning. And always test groups at 100, off a solid bench rest. Once you have a consistent group at 100 you can then sight in according to ballistcs tables. A 69 gr bullet will be about 1.6" high at 100 yards, then sight in 3" high at 100 to be on target at about 250 yards.

 

[Dmay]

I tend to respectfully disagree - IMO 200 yds will magnify the difference in your groups better than 100, assuming good atmospheric conditions.
As stated however, one good group doesn't necessarily mean much, consistancy is more important.
Varying velocity, powder, or bullet when searching for an accurate load usually has more impact than seating depth -which can then be used to fine tune. (Maybe you have already been through all that.)
Again, only my opinion - I ain't no kind ekspert.