Seating depth triumph

I went to the range today looking to put the seating depth mystery up to its first test. I was using my 175Gr SMK load and placed the bullet 0.005″ closer to the lands for each five shot group which looked something like this:

  1. 2.075″
  2. 2.080″
  3. 2.085″
  4. 2.090″
  5. 2.095″
  6. 2.075″

The final test would have the bullet jammed into the lands 0.005″, thus I had to be cautious and watch closely for signs of high pressure as I shot each group. The bolt became stiff to lift on the last two groups, but no other signs of high pressure were noted.

Starting from the top left, group 1 and 6 were my control groups using the original 2.075″ measurement. Groups 2 thru 5 were the test subjects. I am very pleased to see that the groups tightened up as I moved the bullets forward.

Groups measured at:

  1. 0.887″
  2. 0.505″
  3. 0.752″ I pulled that one flyer so it should have been closer to 0.368″
  4. 0.488″
  5. 0.611″
  6. 0.620″

Group 3 and 4 are the best by far. I now know that these bullets are going to like sitting very close to the lands. Somewhere between 0 and 5 thou jump will be the optimal position. I plan to confirm this with another test shoot.

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