Re: .308 Win w/ 18" 1-10" twist barrel to 1,000 yards
What does WWBrown mean when he says, "I have been asked to set the rifle up shoot up to 1,000 yards"?
The 1:10 twist suggests heavy bullets. If you are using a Long Action, you could throat the barrel to seat 200 or 210gr match bullets and still have magazine feed functions; but, that would result in a very specialized rifle...
Optimium twist for 168/175 gr bullets is about 1:11. You could theoretically shoot even heavier bullets than 210gr from that 1:10 twist barrel. The 240gr matchking might even be a good choice if you can get velocity to about 2150fps. That bullet could be a single-load proposition, even in a Long Action receiver...
I suspect an 18" barrel is less than optimum for any kind of accuracy, due to harmonics more than velocity factors. Benchrest guys can shoot any length they want, with shorter, stouter contours being preferred. Yet, most BR shooters go for a 20-22" barrel as these seem to be more conducive to tight grouping which suggests harmonics and vibratory waves balance out best at those lengths as bullet travels the tube. Or so I understand it...
To make more velocity, there is always the .308win Ackley Improved. Redding catalogs a die set, plus you can shoot factory loads in any AI chamber...
I have a 21.5" #9 contour Shilen match barrel in ,308AI on Rem 700 LA, but its twist is 1:11. Not interested in 1k yd shooting with this one, but a 180/190 match bullet would likely make the grade just fine.
Seems like about all you can do is optimize what you have to work with for accuracy at 100/200 and go from there. You face barrel issues and action issues, plus cartridge issues; unless you have leeway to optimize for one specific longrange load, and the owner is okay with single-round loading.
No one I have heard of or read about orders an 18" .30cal barrel specifically for 1000yd shooting. Do your customer a favor and suggest a longer barrel or maybe a Long Action.
There is an old saying that goes, "You can't get there from here". While that 18" rifle might put rounds on target at 1000yds, I doubt it will do so with reliable frequency which will approach what others consider 1000 yd accuracy. That would be holding 10 consecutive rds in an 8" circle. That would be about .75moa.
