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Update:
I loaded 5 rounds of only one load, more to evaluate case performance than anything else. I loaded 9.0 grains of H110 under a SMK 168 with a federal 210 Primer at an OAL of 2.800.
First, the 220 grains of lead does not, as I had previously thought, fill the case to allow 300 Whisper capacity, it is still much larger. I was not taking the volume of the flash hole into account.
All 5 rounds were fired from a Remington 700 Tactical with a 20" 1/10 twist barrel. This rifle is usually very capable of 1/4" CTC groups without much effort.
All 5 rounds were definitely subsonic, although, as stated above, my chrono is down so I can't comment on actual velocities.
in 2 of the 5 rounds, the lead broke free of the case and moved to the front of the case, although nothing appears amiss except for this and it did not appear to come forward with enough velocity to deform the case. There is no evidence of fragmentation of the lead that I added to the case and it still appears intact, although moved.
None of the cases showed any indication of excessive pressure.
Accuracy seemed unaffected by the 2 rounds in which the lead separated and all 5 rounds formed a cumulative group slightly larger than 1/2" CTC.
If I go forward with this idea, I will probably add more lead to reduce case capacity further. My first thought was to reduce the diameter of the flash hole by NOT drilling the flash hole larger and then using a smaller piece of wire to form the hole in the lead, however I am reluctant to do this for fear of inconsistent ignition since the entire powder charge is nearer the front of the case and so far away from the primer. Instead, I may leave all as is with the exception of adding more lead to further reduce case capacity.
I will also have to consider the cases disposable or at a minimum re-melt the lead inside each as I can not guarantee to reposition the lead filler exactly the same as it had been before separation in those cases that do separate.
I'll post more as this project progresses.
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