BCB
03-17-2014, 05:57 PM
Got a 23” T/C Carbine in 6.8mm SPC…
It has been shooting VERY well with jacketed bullets—plenty of data for those critters…
I did shoot some 280642 (~150 grains) just to fireform brass in the beginning using Trail Boss—really don’t need much data for that other than the 70% rule…
They shot quite well, but they are simply too heavy in my opinion…
I did get some 130 grain gaschecked cast boolits today. Again, I can always start with Trail Boss, but I would like to use some other powder to get me to 1700-1900 fps…
Accurate lists a charge of 20.2 of 5744 for a 130 jacketed bullet—2139 fps…
I wonder how much I could reduce this charge and still be O.K. as far as ignition and nothing leading to high pressure because of too light of a charge?...
How about SR-4759?...
There is considerable data for the 130 grain bullets with powders of the burn rate up to the mid-range stuff—H-335, 2015, H-322, etc…
How much below starting charges could these be reduced? Starting charges give too much velocity according to published data…
Any Help?...
Dang nice little cartridge this 6.8mm is, but cast data is almost nonexistent…
Thanks…BCB
It has been shooting VERY well with jacketed bullets—plenty of data for those critters…
I did shoot some 280642 (~150 grains) just to fireform brass in the beginning using Trail Boss—really don’t need much data for that other than the 70% rule…
They shot quite well, but they are simply too heavy in my opinion…
I did get some 130 grain gaschecked cast boolits today. Again, I can always start with Trail Boss, but I would like to use some other powder to get me to 1700-1900 fps…
Accurate lists a charge of 20.2 of 5744 for a 130 jacketed bullet—2139 fps…
I wonder how much I could reduce this charge and still be O.K. as far as ignition and nothing leading to high pressure because of too light of a charge?...
How about SR-4759?...
There is considerable data for the 130 grain bullets with powders of the burn rate up to the mid-range stuff—H-335, 2015, H-322, etc…
How much below starting charges could these be reduced? Starting charges give too much velocity according to published data…
Any Help?...
Dang nice little cartridge this 6.8mm is, but cast data is almost nonexistent…
Thanks…BCB