I am loading for a Howa Mini with a magazine length of 2.415" (Oregunsmith's bottom metal). Based on my rifle's chamber, the COAL (max) is 2.263" (OAL Gage) with a corresponding CBTO (max) of 1.669" (Sinclair bullet gage). My initial load development was 29.5gr - 31.5gr XBR with a CBTO load length of 1.644" (2.20" COAL). This seated the base of the bullet approx. 3/4 into the neck. At approximately 30.5gr, the powder volume level located at the base of the neck (neck/shoulder junction).
I am planning to extend the seating depth (shorten the jump) to 1.660", which would place the bullet 2/3 into neck. Decrease bullet jump = increase gap/space between the bullet and powder (i.e. decrease case fill) In perfect world I like to have good case fill and also ability to play with bullet seating depth. Out of curiosity I wanted to know how much powder would fill the case with my current CBTO. At 32.8gr the case was completely full with no loose powder felt when shaking the cartridge and not compressed. This is +1.3 gr above max loads...theoretical exercise.
My Question: Most are loading for AR15 with 2.20" COAL for the 90gr TNT. Are you simply living with the extra space in the cartridge or is there a better solution?
Edit: As I come back and revisit this post from late last night (after work), I realize that the 1.3gr free space over a normal charge weight means a case fill of 90%-95%. This seemed much worse during the Shake Test because of the the length of the gap/running room in the neck amplifies the sound/feeling of the empty space.
I am planning to extend the seating depth (shorten the jump) to 1.660", which would place the bullet 2/3 into neck. Decrease bullet jump = increase gap/space between the bullet and powder (i.e. decrease case fill) In perfect world I like to have good case fill and also ability to play with bullet seating depth. Out of curiosity I wanted to know how much powder would fill the case with my current CBTO. At 32.8gr the case was completely full with no loose powder felt when shaking the cartridge and not compressed. This is +1.3 gr above max loads...theoretical exercise.
My Question: Most are loading for AR15 with 2.20" COAL for the 90gr TNT. Are you simply living with the extra space in the cartridge or is there a better solution?
Edit: As I come back and revisit this post from late last night (after work), I realize that the 1.3gr free space over a normal charge weight means a case fill of 90%-95%. This seemed much worse during the Shake Test because of the the length of the gap/running room in the neck amplifies the sound/feeling of the empty space.
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