I'm thinking about building a retro type rifle with a surplus upper (GI Profile 1/12 Twist with birdcage fh), BCG, buttstock, and buffer tube assy on a NoDakSpud Lower with a standard LPK. What type of accuracy can I expect from a build of this type? I want it to be able to shoot out to 400 yards from prone. What could I expect at 100 yards from a stable rest with good ammo?  This would be my first build, I like the M16 Style and really want one of these but if accuracy is no good I might have to build/buy something else. Thank you for your help,

-Mo.

If you exclude the one AR I built for precision shooting I would say I get about the same amount of accuracy out of my retros as I get out of my more modern ARs, relative to the optics.

Several of my retros have the Colt 3X scopes on them and they have about the same accuracy as my modern ARs with ACOGs.

I can do about the same with iron sights on all my ARs.  If anything I do a little better with the retros.

A retro AR will not be a precision shooter but it will get the job done

I and all the other Marines of my time qualified at 500 yards with an A1. We called the 500 the gimme line. Slow fire using the sling and prone with large targets made it easier than the other distances.

Is the surplus barrel you're using new with the wick in it, or has it had 20,000 rounds of full auto fire through it?

So, it would be well suited for things such as Appleseed KD Shoots as well as varmint hunting (Within 200 yards) as well as general target shooting up to 500?

I have no idea, I will ask the seller about this.

My XM16E1 clone (M16A1 Colt parts kit) sounds exactly with what your looking to purchase. This group I shot was using a $125 1/12 twist aftermarket barrel @ 25 meters. And the other target was @ 100 yards. Need warmer weather to actually dial both in better.

This rifle was a LGO kit, with a 1:12 Green Mountain barrel front sight drilled and taper pinned by none other than the great John Thomas. Lower is a stock pre-ban Colt HBAR. Shooting cheap-o brown bear steel case, sitting, iron sights at 100 yards. IIRC, this was a 20 round mag's worth.

If you know how to shoot...500 meters is not an issue with an M16A1!!!

While it is certainly possible to get decent accuracy from retro rifle parts, the design itself is not inherently designed for match shooting or long-distance sniping.  It was designed to shoot minute-of-man at normal combat distances.

Just some of the factors that will negatively affect your groups:  
--That slim pencil profile is nice and light, but very susceptible to heat effects.  As the barrel heats, the point of impact will change.
--That GI chamber is reamed to a miltary 5.56 NATO spec.  It's not likely held to the same standards as a quality match barrel.
--Those triangular handguards are retro-iconic, but the barrel is not free-floated.  Any pressure on the guards is transmitted into the barrel and will be seen in the printed group.
--The standard fire control group is reliable enough for combat, but the trigger has its limitations.  A good smith can tune one quite well, but most military triggers are creepy and heavy and rough (oh my!).
--The rifle is lightweight.  Your every heartbeat will bounce that front sight post.
--As someone else mentioned, many components that we use for retro builds are used surplus of questionable background.  They may last a long time, but they do wear, and excessive wear is anathema to accuracy.
--And if you enjoy shooting the old rifles as much as most of us here, you'll burn a lot of ammo so at some point you'll probably start buying the "cheap" stuff.  Now some of the cheap stuff is perfectly fine for plinking and everyday shooting (I shoot a LOT of PMC Bronze through my retros), but it's not match ammo.  Heck, even the military specs for M193 (55gr) ammo only had a requirement of 2 or 3 MOA, if I recall correctly.  (Someone will be by with the right numbers, I'm sure.)

Put all that together, and you'll be lucky to average better than 3-4" groups at 100 yds.  Carefully pick the best-condition parts and use good quality factory ammo, and you might see 2" groups.  But it takes some serious retro-smithery and careful load development to get authentic A1 parts shooting anywhere near 1-MOA.

Of course, there's a lot more than accuracy going for these things.  They're lightweight, they're historic and they turn a lot of heads on the range.
But in most cases, accuracy is just "ok."

If you can live with that, though...brother, you have come to the right place!
Post photos as you go and feel free to pick the collective brain of this sick little hive!

If this doesn't bring back 37yr old memory's. For some reason I would always drop points at the 300yd line during the standing to sitting timed fire. But I always made up for it at the 500yd line. The M16A1 is not a match grade rifle by any means. But it will touch you from long distances away if need be.

That accuracy sounds perfectly fine to me. I can use higher quality hunting ammo for varmints and match grade stuff/hand loads for target shooting and cheap Surplus for plinking. Sounds perfectly adequate for my intended use. Thanks again for your help, guys!