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seating depth for accuracy Question

bpost
I have found a load that gives consistent good groups at the book recommended bullet seating depth. What is the rule of thumb for finding the sweet spot for seating depth. I went almost .30 deeper tonight and tightned up the group by almost 1/2 inch. How do I proceed with this process? What increments of change in depth are reasonable? This is not a high end match rifle. Its my "old Gal."

rifle, 1903A3 2 groove barrel
Optics, Burris 8X32
Load 46 gr IMR 4895, very mild
Cases, FA 61 Match trimmed to 2.485 and neck sized .220 down the neck.
Bullet, 168 gr MK
Tightest group so far .784 at 100 yards low wind.

Your words of wisdom are appreciated!
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2 comments

Date Votes
  • rufe-snow
    This business about "seating depth" is a can of worms as far as I'm concerned.

    Some folks swear up & down that .010 off the lands will get you the best accuracy. From my experience thats so much hokem.

    It's a matter of trial and error, i.e. some rifles ( 96 Swede Mauser ) are so long throated you can't get a lighter then standard bullet .010 off the lands, if you wanted to.

    luger_4.jpg
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  • Hunter375
    It depends entirely on your rifle. Some of mine like to be very close to the lands (<.015"), while others prefer .050" or more freebore. What I have found to be more critical is case dimensions. Use a neck sizing die instead of full length. Less trimming and the cases are perfectly formed to the chamber. This has a more substatial benefit with long actions (do not do this with autoloaders, though). I have also had better luck with powders that use more case volume, especially compressed loads; more efficient burn due to symmetrical powder column. Basically, you're just going to have to play with it until you find that "sweet spot".

    Save the seals-club a liberal instead.
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