barrel length and chamber for 5.56, 77 grain loads in a bolt gun?

[QueensHorseman]

Hi all,

For a fun shooting, easy carrying, coyote hunting rifle, what would be an optimum barrel length and chamber spec for factory 5.56, 77 grain loads? I have a model 70 in .223 Ackley and was thinking about rebarreling it to a standard chamber to shoot the 77 grain loads. My standard barrel length has always been 24" but with this little case, I'm thinking a 20-22" barrel may give me most of what the round has to offer with nice hunting portability. Also would a Wylde chamber be best considering the use of 5.56 factory rounds / pressures vs a normal .223 chamber? I would certainly want to maximize the throat for the 77 grainers (Nosler 77 grain OTM bullet). I'm assuming a 1-7 twist barrel.

Thanks

 

[tiriaq]

What is the twist in your .223 Ackley? If it is 1:9 or faster, 77gr SMKs should be just fine. The Sierras are designed so that rounds will fit the AR magazine. Consequently, a standard chamber is OK. A Wylde chamber would be good in a new barrel, if you want to shoot 5.56 ball as well. The 1:7 was developed for the long 5.56 tracer bullets. Unless you are going to be loading extreme VLDs, a 1:8 might be the best choice.
In an AR, the 77gr SMK shoots well in a 20" barrel. .223 long range shooters often prefer very long barrels - up to 32". I wouldn't go less than 20", up to 24 or 26 can still be handy, depending on the barrel contour.