While researching loads and testing COAL for my new 270 WSM rifle, I realized that some of the new brass I had bought for this caliber didn't fit in the chamber properly (making bolt handle hard to close)
The brass is made by Federal and the rifle is made by a very reputable European manufacturer. This was without seating any bullets so I thought the brass length is to long. I checked the case lengths and they were within specs. Next I checked the average base-to-shoulder length of a set of "OK cases" and compared with a set of "not-feeding cases". There was a noticeable difference in the average length of the two sets: The no-feeding ones were about 0.1mm to 0.15mm longer than the others on average.
To solve this problem, I full-length-sized some of the non-feeding cases but I realized that my die didn't change the shoulder position!!
This implies that the brass is within SAAMI specs so to make the die push the shoulder back, I filed the bottom of my die using a piece of sand paper. After a couple tries, I got the die shortened enough so that it now pushes the shoulder back by about 0.2mm and the sized cases all fit the rifle chamber.
My experience seems to be consistent with the so-called Delta-L issue:
https://en.wikipedia.org/wiki/Delta_L_problemHas anybody else experienced a Delta-L problem?
