OK, I am having a bit of trouble trying to match a barrel(s) to my needs.
I am in the process of building an AR for me and one for my eldest daughter, while collecting parts for my younger daughter until she is old enough. I have all three lowers.
The requirements for the guns are pretty simple. Range practice/informal steel to 200 yards or so. I have a single shot .223 for varmints, however my gun could see some light use for that as well, but not very likely. I figure that if my single shot gun kicked the bucket (can't get parts easily for it, so that is a possibility) then I would work on more precision set up or get a bolt gun of some sort. I also have a 300 blk pistol and we have more appropriate game guns.
I have no plans to run heavies, and I have lots of 50 grain ammo around. I do reload. I want them to be fairly light -under 8 lbs with a dot or low power scope. Not including magazine.
I have read that a mid length gas would have a softer recoil impulse, than a carbine gas. I can find a lightweight mid length, but they are almost entirely 1:7, which seems a bit fast for my needs. 1:9 seems more appropriate. I can find 1:9 but they are carbine gas.
Then the profiles. I see mid weight, govt, lightweight, and m4. It seems that the government and midweight are almost identical and the m4 is a trimmed down mid weight. The lightweight seems to be lighter yet. Am I correct in this?
Then I have a question on the bcg's. I have read on one source that 16" carbine gas and shorter recommended full auto bcg(which I have in my pistol). 16" mid and longer recommend a semi bcg. Is this correct thinking? Will I run into issues should I decide to got full auto bcg with a 16" mid? I like the idea of having all the guns run similar parts.
I have no plans to build $1k AR's. I just need them to work, and they don't need to do one hole at 100 yards.
My inclination is to go with a lightweight mid 16" barrel and full auto bcg to be run with a carbine stock, spring and buffer. The twist "problem" may just be a stigma for me and have no real meaning. Should this combo work or will I need to make adjustments to that plan?
A lot of people do claim middies are softer; subjective and if there is a difference, it is small. That said, no reason not to go with a middie. Unless you are going for ultimate accuracy I wouldn't worry about the twist rate: 1:7 will shoot anything well.
As for profile, I would go with something like BCM's Enhanced LW; here.
Everyone runs full-auto BCGs these days.
The configuration you list is perfect.
As for a barrel, I recommend looking into the LaRue Tactical PredatAR barrel. It is a 1/8 twist. They are still $225 and, according to the last word I saw from Mark LaRue, they will be this price until the end of the year and them they go back to regular price.
LaRue Tactical PredatAR barrel
I used one for a recent build I did. This build comes in at 6 lbs. 2.8 ozs. with an empty 30-round polymer magazine.
As far as BCGs go, All I run on my ARs is the full-auto M16 type versions. It makes no difference if it is a carbine, mil-length, or rifle gas system. It works great with any system. I do shoot full-powered factory loads like the M193 55 gr., M855 62 gr., and Mk262 77 gr. OTM. Some guys, like 3-Gunners, will run lighter bolt carriers with lighter custom loads and have their gas system tuned for those loads.
Something to consider.
Thanks for the input so far guys.
The loads I have were worked up in my previous AR which I traded off. They were .5 grains over my varmint rig load, and 1.5 grains under max. I had also tested those loads in the varmint rig while working up a load for it, and knew it was safe, so I just left it be.
I will start some more serious research on the barrels now that I have it narrowed down some. I also have to wait for Christmas to get over before I start buying more gun stuff
Twist rate doesn't matter if you are sure you never want to try anything heavier than 50 grains. A 1/7 or 1/8 twist will still shoot light bullets into tiny little groups and allow you to try the heavier bullets some time in the future. 1/9 twist is stuck in the 1980's when the heaviest bullet on the market was the 69 grain SMK.
I would buy a barrel, bolt and bolt carrier from White Oak Armament and call it a day. The full-auto BCG won't hurt a thing. You may have to balance the action out with heavier buffers. I personally can hardly tell the difference in recoil impulse between carbine and mid-length gas systems when shooting.
Unless you want a really light rifle WOA's SPR barrels are some of the best I have ever fired. I always recommend their barrels first. They are a mid-weight profile, not light by any means, however the weight will reduce felt recoil if that's an issue for your daughter. Check out Rainier Arms barrels, they have a wide variety of quality barrels to choose from too.