Thread: Bullet Seating depth and pressure (6.5 Grendel)

Background - We've been developing a load for my sons 6.5 Grendel and have found an accurate load at 27.7 gr. of ADI 8208 with 123gr. Hornady SST.
(We've used load data from ADI which lists a max load of 28.5 gr. 8208 but they do not list the SST specifically rather a 123gr. Sierra HPBT so we ran with that.)

All our loads so far have been at 2.260" COAL, but when I loaded up some more rounds of 27.7gr. to verify last weekend, whilst setting up the seating die I slightly over seated the first round closer to 2.250" COAL and I thought no worries, I will do three like that and use them for warm ups.

Well, all shot good with no noticeable pressure signs, no hard bolt lift or flattened primer etc. But after reviewing the brass back home I was surprised to see some of the loads show a very (very) faint ejector mark on the case head. I did not notice it whilst shooting and only because I used a magnifier glass back home.

This is where it gets interesting because the three rounds loaded at 2.250 do not show any ejector marks at all.

Question to those who are still with me:
1. Before I load some more up to verify is what I am seeing pretty typical that reducing seating depth reduces pressure ?
2. Are very faint ejector plunger marks a worrying sign to over pressure. (the only other rifle I have loaded for is a Mauser so you would never know)

Cheers guys