If you were to look at something like a commercial .308 barrel blank, it would be something like .298 - .300 lands.  I think that was the problem with the S&W barrels, the lands are only .217 on a .221 bullet.  BA said that info was proprietary when I asked them, but I would guess they're more like .214.  That may be why AA switched to Voodoo?  S&W and AA used to get their barrels from T/C several years ago.

Damn, that sucks.  I picked up nitrided stuff for that reason alone.

Same results here, low round count on my barrel and good accuracy with 7N6 but mediocre results from most commercial ammo. 1 in 9 twist.

As for running a chrome lined or nitride barrel as  replacement for cleaning, I wouldn't. My first build about 6 years ago was a 7.62x39 upper with a stainless steel barrel for corrosive Yugo M67. I'd give it a thorough cleaning but basically cleaned it like it normal. The bolt face & gas tube immediately started showing signs of rust. That's when I started cleaning it like my black powder rifle (flush with a LOT of hot soapy water) and haven't had any issues since.

Keep in mind this is also an issue of humidity. If you're keeping your rifles in a very low humidity climate, corrosive salt isn't as much of an issue. Doesn't mean it's not there. What works for some one in Arizona won't always work for someone in Louisiana.

I'll point out that nitride ain't perfect.  You still need to clean the barrel, but you don't have to worry about rust on the way back home from the range.

My nitrided 5.45 barrel was easy to clean (like all nitrided barrels) and that was a big selling point.  I also went with a gas piston option (it's a Huldra-branded upper, made by Adams Arms with a Voodoo barrel) to keep the salty crap out of my lower.  But as long as you plan to clean the gun fairly promptly, you'll be fine.

Finally, Ol' Grandad marched through Europe with a Garand that had an unlined barrel and fired only corrosively primed ammunition.  His drill sergeant beat "clean it often, clean it well" into Grandad's head, and as long as he followed that advice, his rifle was fine.  My Korea-vintage Garand had nothing but corrosive ammo through it, and it's still beautiful (though it shows some substantial use).  Corrosive ammunition is not "deadly poison to rifles."  It just requires the shooter to take care of the rifle.

I ran a bunch of 5.45 through my HuntertownArms 5.56 Kestrel , don't think I ever cleaned it - just flushed it out with water after I shot it. I realized last month I couldnt get it apart

Thanks!

I've never had a problem with corrosion in my S&W lower (DI rifle). However, I rarely clean my upper/entire rifle. Hot water rinse is all the corrosive ammo requires and if I don't do it, the corrosion is rapid and evident in Virginia's humidity.