I’m starting to look at building my first .556 AR for general plinking and coyote hunting. I wouldn’t picture shooting more than 300yrds often. Does anyone have recommendations on what they have found works well for them? I’m not looking to spend a fortune, but not going cheap either. I’m new to the AR game and a little lost with the options out there. I’m thinking mid length with an 18” barrel unless recommended otherwise. What twist rate should I be looking for? As always, any suggestions is appreciated!

I went with a 20" Wylde chambered heavy stainless steel fluted barrel upper from Palmetto State Armory and it has been going well for the last 7 years and I don't know how many thousand rounds still shoots half MOA or better. I built it on a 80% lower with a drop in trigger. Twist rat is 1:7

300 isn't that far

free float is what you want however

I wouldn't worry about heavy barrel , 16,18,20 you pick up a touch of velocity but not that much about 100fps in a 20 vs a 16

mid length if 16 or 18 and rifle if you go 20

mid and rifle are less jumpy than carbine gas systems so less movement of the rifle while shooting, carbine over gasses to insure function , which isn't really an issue when no one is shooting at you. they still work a ridiculously high % of the time like 99.9998% and you basically had to neglect any cleaning or gone for a swim in a muddy creek.

1:8 wild chambering would be ideal 1:8 is about the most forgiving to a wide range of bullet weights and yld is a compromise on 223 and 5.56 nato chambers that will still safely in semi auto fire and take both rounds without being as generous as the nato chamber so your bullet has less free jump to the rifling

although 1:7 can shoot 55s fine also and 1:9 does them well look at what is available

if we 55gr values for 5.56 pressures 3187fps for 16.5 inch , 3202fps for 18 and 3306fps for a 20"
https://rifleshooter.com/2015/12/22...ngth-and-velocity-26-inches-to-6-inches/

with a 225 yard zero
I am just going to use my bullet for the calculations
55gr Hornady BTSP b.c. 0.235

3187fps 16" barrel 1.9 high at 150 and 1.4 low at 250 5.5 low at 300

3202 fps 18" barrel 1.8 high at 150yards 1.4 low at 250 and 5.5 low at 300

3306 fps 20" barrel 1.7 high at 150yards 1.2 low at 250 and 5 low at 300

you could play around with exact zero distance and such but the 150 basically represents the highest point and the 250 yards where it is headed back down and your going to have to do something for 300 regardless to adjust

so just answer is the added weight and length worth it for 1/2 inch at 300 yards and you will know what you want to do.

16 will have less whip and be a bit more rigid with less weight your also not dumping mags at coyotes so in 3 rounds even a lighter barrel may do fine

Stainless , Nitride or Chrome lined all make good barrels with a slight nod in accuracy going to SS and Nitride but I have a Chrome lined that does just fine also

Thanks guys, that’s a lot of really great info. That'll make my decision a lot easier.

I have lots of upper for sale, if you are looking for one that is put together.

Nothing about the original question, but getting a decent trigger for that rifle does as much if not more for the accuracy of it than the style of upper you use. You can work those Military style triggers over to get them to half decent performance but it is a lot easier to put a ready made trigger assembly in it with the specs you want from the get go.

Following closely as my son and I are also going to be building a few. Triggers - I have heard about Larue Tactical making a nice trigger - any better out there that are reasonable and I should look at? Are Bear Creek lower and uppers decent? Who makes the easiest 80% lowers that are decent quality. My son is 13 and loves to read and build. Legally, he informed me, he can build his own - I really had no idea but I truly like the concept of him buidling a rifle he will eventually own.

Of the 4 rifles I’ve put together, I’m most happy with my White Oak Armory barrels. Smooth gas system and that barrel shoots a nice group and doesn’t seem picky with ammo. LaRue 2 stage is nice for the money. I also really like the Wilson combat triggers for the money. Wilson has sales for just about every holiday, so if you can wait you’ll save some coin.

bear creek is the buy up other places left over parts from contract runs and make uppers out of them company for the most part they are not anything anyone says yeah that's the rifle I want to take into a fire fight if they have other options.

technically most things are MIL spec meaning they had to fit a standard to be used but if your buying the overrun or blems not a guarantee.
you should test any gun before you take a big trip or need it , like many other budget guns and uppers you are the QA team make sure it all works you may have to send it back to get it right.

some people have gotten great stuff from bear creek that does all they wanted it too others need to do work or send it back.

80% I have only done a few I ordered them from Midway they worked , can't say if they are the best but they worked.
I have a friend who likes 60% lowers he wants to machine the shelf to mate to the upper so it locks up tight without needing a wedge
most 13 year olds don't have the machining skills or would need to buy the router kit and that tooling costs more than buying lowers.

Larue makes a good trigger for the $ the ALG is also a good trigger for the $
these are more of a hardened polished MIL spec type trigger it smooths it out and drops weight a little but keeps it around 4 pounds typically, the other option is a drop in that is contained in a housing , these are a bit more money and offer 2 , 2.5, 3 and 3.5 pound or adjustable trigger weights

a solid way to build that takes you buying the lower is buy an Anderson lower as an other and build on that , your not out much money 55-65 dollars you can always reuse it for another build if you do an 80% later but it gives you a solid budget start to building your first AR
most stores carry these I have bought a couple at Fleet Farm if I was filling out papers on something might as well toss a 50 dollar Anderson on the bill

PSA is also not a bad place to get parts or lowers

there are apparently only 4 forges that make all US AR lowers so then it is who finishes it and drops their name on it

I have put AR's together for over 40 yrs. I use good barrels and drop in trigger. You get out what you put in. I use Anderson lowers and Odin lower kits. The barrel that I have found to shoot the best are Krieger and Shilen are the top two. Then Odin, Blackhole weaponry, and Faxon just to name a few.

I was looking at the geissele SSA-E for a trigger. Can get it for 199 at brownells, but the larue looks pretty enticing for 115. I don’t want something with a super light trigger pull as it will likely be used some in cold weather with gloves. Any experience with the SSA-E trigger? Will I get more out of it than the Larue for the price?

look into a 6mm ARC, awesome little rifles

I have the jigs to mill and drill 80% lower receivers. If you are planning on building just a couple or five, you are welcome to borrow them. You will need to get your own routers but they are cheap enough.

I have 3 of the larue mbt-2, great triggers for a hunting rifle.

.223 has a wide range of ammo options I’d go with that.

the velocity single stage is a decent trigger, 135 bucks I think I paid for them, find them at grendelhunter.com

With my 24" .223 the bullet would drop a good amount by 300 yards, if you know the yardage and where the bullet will be 3-400 yards is ok
I had a 56mm scope, sighted in 3.5" high at 100 yards, it was dead on at 280-290 yds.
4320 imr powder
A shorter barrel the bullet will drop sooner than a 24-25" barrel

A couple of AR's I have put together.

I have one, they are about as good as you can get. The Geissele SSA-E is a two stage trigger. It's a 3.5 lb trigger, 2.3 on the first stage and 1.2 on the second. If you feel that's a little light the SSA is a 4.5 lb trigger. You'll like it, takes a little getting used to a two stage if you haven't used one before. A lot of Seals are running the Geissele's. Timney makes a couple good triggers, Impact is pretty good, Competition is better. I have a couple buddies that swear by Hyperfire.

I've never understood why people dump a nice chunk of change on a rifle and cheap out on the trigger. I cannot comment on the Larues.

As far as barrel is you primary purpose hunting and shooting? Are you also looking for it to be a good home defense rifle? Or do you see yourself going down the AR rabbit and building/buying multiples?