Gunsmithing Speccing AR10 barrel: Gain twist, taper?

[Hygienist]

I'm ordering an AR10 barrel, the blank which I'd like to get from Bartlein. It'll be a 16.5" .308 Winchester bbl.

I'd read that the top competition shooters are starting to use gain twist, and I'd like to look into it if I can get more info. I'd like to go all the way up to using 208 gr A-Max's (guessing 2300FPS, maybe a bit more, once I get the load done if that's a factor), which I assume would necessitate a 1:10 twist for a regular bbl. But for a gain twist, what would that translate into? And is it suitable for a high volume fire semi? I'm having trouble locating any info that describes exactly how to determine what to set gain twist at, so if anyone happens to have a link or info on that I'd appreciate it.

Also, I'm trying to determine the taper. I'm imagining the baseline as a straight .750" medium contour. What's the best way to make a taper version of that so it weighs about the same? I was thinking somewhere along the line of .850" at the beginning to .650" at the end so that it's still an average .750" overall. Is this an optimal taper, too much, or too little for the 16.5" bbl?

 

[WhiteHorze]

Okay I'll bite:

1) There's no reason to use a gain twist barrel. There's no advantage in accuracy, durability, or cool factor...

2) For a 16" barrel, You don't need a straight taper. Just grab one off the shelf, take it out and shoot it. Then you'll know how heavy a barrel you'll want in order to maintain stability but not slow you down with deadweight.

 

[bohem]

I'll add another item, as I agree with the first 2 comments from the previous poster:

3) You can stabilize a 208 Amax from a 10tw in a 308 16" barrel without trouble, go a little faster if you're shooting a lot in super cold weather near sea level (like a 1:9.5)
4) Comment #3 is totally moot if you're using a gasser and you want it to feed from a magazine, the shortest you're going to reasonably get the 208 Amax in a 308 case is appx 2.93" and that's 0.080" longer than an Armalite pattern magazine and more than 1/8th inch longer than a DPMS pattern magazine.