Last fall when it was cooler, I workrd up a load for my 308 Winchester using CFE223 and Sierra 168 Matchkings. I came up with a final load that was listed as 1.5 grains under max according to the book. This load was very accurate and I shot probably 30 of them through the rifle with no pressure signs.
Yesterday I took them to the range and fired 6 of them. Two of the last three blew out the primers but were not hard to extract. I checked the others and the primers were flattened.
I pulled the remaining rounds apart today and weighed the charges. All were right on the money for the load notes I made when I loaded them.
Accuracy was not as good as last fall.
The load data was as follows
Cases--Perfecta
Powder--47.5 grains CFE223
Primer--Federal standard LRP
Bullet-- 168 Sierra Matchking
OAL--2.855(bolt rifle seated .015 off the lands) This is a custom length for this rifle as measured using a Hornady bullet seating gauge.
Case volume appears to be the same as Winchester or Federal brass.
According to the Hodgdon data site, I am 1.5 grains under the max load for this powder/bullet combination as well as .055 longer on OAL.
Temperature when I worked up the load was 38-45 degrees F. The temp yesterday was 85-92 degrees.
Since this combination worked so well last fall in cooler weather, I have to think the powder was displaying temperature sensitivity.
There was no damage to the rifle and my other target load (different powder but otherwise same components) still shot excellent groups.
What are your thoughts?