i'm going to have a garand rebarreled to .308 very soon and was given a choice of four or six groove in a douglas meduim heavy contour barrel. plan to use 168 sierra bthp matchkings through it.
any reason why i should choose one over the other? thanks in advance.
I've used 4 groove Douglas barrels in 1-10 twist with very good results using 168gr.sierra bullets.Gene Barnett does the contour work on those.
I've re-barreled about 2000 M1's using that barrel.Here's how it should be done to get the most accuracy.
4 groove barrels are also easier to clean (I hear).I believe Gene only makes heavy barrels for the M1 (I could be wrong).
sight alignment gauges must be used to line up sights (there's different ways to do this).
once barrel is installed and sights lined up,headspace should be kept within 1.6305-1.631 for a match chamber (don't shoot surplus ammo).
Pull thru match reamer should be used to headspace bolt to the barrel (clymer).
One last thing that I can think of is this,
DON'T EVER RECHAMBER A 308 BARREL TO 30-06.
308 barrels have a bigger gas port (that's the reason) and will recoil beyond belief.
Go with the four groove. The 168 gr SMK bullets will work fine in either; however, bullets with "harder" jackets like the 173 gr M118 Match ammo don't always grab the finer 6 groove rifling consistently. The four groove barrels shoot almost anything you put through them.
In his M14 video "Center X",Art Lupino says for overall shooting, use the 4 groove barrel.The 6 groove is for the thin jacketed commercial bullets like the Sierras.He states that the 4 groove is better for the thicker jacketed military match bullets such as the 173 gr that Lake City loaded.
I had a TRW M14 with a Heavy Douglas 1 in 10", 6 groove barrel.That rifle was a tack driver with Sierra 168gr Matchkings.I was getting 0.25 MOA to 0.50 MOA out to 300 meters, and could make called one shot hits on spent .38spl cases at 200 meters.