7.62x39 subsonic with trail boss

Duncan71 said:
How many grains of trail boss do I use to make a 150gr bullet go subsonic. Thanks, and I couldnt find anything on the search.

Cheers
Duncan
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Duncan... there are a lot of factors affecting the sonic zone (elevation, temperature etc...), not to mention the physics of barrel lengths, bore condition etc... Its best to work your load "down" with a chronograph and find what works best for you. 10 grains of TB should put you in the 1175 fps range... which is a tad supersonic... start there and work down.

Here is a link to TB data... including a formula for cooking loads;

http://www.imrpowder.com/PDF/Trail-Boss-data.pdf
 
My old notes were lost in a basement flood 10 yrs ago, but I once played around with sub-sonics a lot. I made up a fairly hard hitting round by loading (and this is from a 50yr old so take the memory for what it is worth) 11gn of Unique to push a 220gn Sierra Game King down the road at just under 1100fps. I was in NS at the time, so pretty much sea level. I have some left over but no time to pull them to check powder loads. One SKS cycled them fine, another you had to #### it every second or third round. Working nights, will dig them out and post pics tomorrow, but I'm not pulling them! Renovating a kitchen.
 
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