Seating Depth adjustments.

[dusterdave173]

I agree that 223 seems less sensitive to depth but the heavy 223 bullets wake up with correct depth
And like you I started 6mm and wow! Wrong depth? No good-- When I put the 107 SMK into the lands just deep enough to get a "square" looking mark or engraving then look out! That baby went to Work! Groups quit being groups and started being one hole

 

[Idaho-Lefty]

@ dusterdave,.
Yup,.. agree, as,.. My group's, SHRANK noticeably,. when Jamming, the 107 gr SMK's in my 6 XC.
It Made, a serious,.. "Difference" ! ( .4's to,.. .2's ! )
Thankfully, my Barrel has, a relatively Short, Freeebore.
A Jammed Bullet gives, the chambered Cartridge,.. ONE More, "Support" Area. ( I think ).
Base of, Cart, Shoulder area, touching lightly and the Bullet, "Held" / aligned with Bore,.. Tightly.,.. JMHO
All I know, IS that,.. It,. really, Works !