See picture. These are 44 SPL+P loads.
Load with the extra little dent was 12.5 grains of Blue Dot pushing a 240 grain MP-429244 small HP pin. This load should be less than 12.5 grains of BD as a standard weight (255 grain) 429244 is 12.5 grains of BD. Velocity 1225 FPS from my S&W 624 6.5."
Normal load is 8.5 grains of Unique pushing the same bullet for 1090 FPS in the same revolver.
I've noticed this before with heavy charges of 2400 with both the 429215 and 429421. It seems to be recoil related as the pressures of the 8.5 grain Unique load and the 12.5 grain BD load are withing a couple thousand PSI probably.
No measurable difference in case web expansion.
Anybody have an idea of what is going on? The revolver has two changes I've made from factory configuration. It has a Pachmayr presentation grip and I put in a Wolff Type I hammerspring which should run at factory weight and a reduced return spring. 624s were made in '84 and '85 I think. They have a regular type of firing pin attached to the hammer. They hammer on a 624 is odd...it is not case colored like other stainless guns. It is a stainless part as well and it is the target style so it is a heavy hammer. I thought this may be related to bounce. Endshake is ~.004.