hey all, I wanted to try some 69 gr sierra match kings in my 220 swift. For the life of me, I cant find any data on line or in any of my books. Thought Id see what you guys thought.
Thanks.
Henry.
hey all, I wanted to try some 69 gr sierra match kings in my 220 swift. For the life of me, I cant find any data on line or in any of my books. Thought Id see what you guys thought.
Thanks.
Henry.
That's because swift rifles are typically 14-twist. Even at an ambitious launch velocity, you will never get that long of a bullet stable.
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
I'm a firm believer in the theory that if it bleeds, I can kill it.
The 69gr SMKs are very unique in there design, with there very short bearing surface, they are more forgiving and act more like
a 55gr than the 69gr that they are, 42-44 gr of H414, Win780, H380, or CFE223 will get you there.
Dean
RUMs are like woman in Stiletto heals, you know they are going to put you in the poor house, but that has never stopped anyone from pursuing them.
awesome thanks guys! glad to hear a positive feedback on the 69smk...
Dean, if i used 43 gr of H380 and the 69 gr smk you think that would be a good place to start? I had thought about using 70 gr data and starting a few gr under but there is no H380 data for the 70 gr data.
Thanks again!
Henry.
Bearing surface, while helpful/hurtful of accuracy; has nothing to do with total length, NOR with the RPM required for stability.
Use the link I posted, look up the length, and fill in the blanks. You will see what does or does not have a prayer for stability with your conditions.
I'm a firm believer in the theory that if it bleeds, I can kill it.
I shoot the 69 SMK in my 22-250AI that is a 1:8 twist. Capacity wise it is very similar to a Swift. IMR 4007SSC works well in my rifle. 3600 fps is easily obtainable in my 28" barrel. I personally don't think the 1:14 swift would have a chance to stabilize a 69 SMK, but heck try it and see what happens. I personal thought a Swift could only shot with a 52 gr bullet....��. Luck, Tim
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