Thread: AR15 Info

Heres a thing I wrote a while back for Tussock about what to look for



-Fast twist barrel - With a 14.5" barrel you need to be able to shoot the ~77gr bullets for .223 to kill larger things well (Goats, etc). 1:7 is ideal and you can still shoot factory 55gr or whatever through it.

-Free floated handguard - The forend. Traditional M16A1/A2 and M4 style handguards aren't free floated, and you can end up with bad accuracy and varying point of aim depending on the pressure you put on the handguards while shooting.

-No fixed iron sights - The traditional triangular 'A2' front sight/gas block isn't desirable for a few reasons - usually they're on rifles without free floated handguards for a start. They're pinned to the barrel and it's a bitch to remove them to replace the handguard. They also end up in the sight picture of your optics. It's easy to get aftermarket irons to mount on your action rail/top handguard rail if you want them - you can get folding "backup irons" (known as BUIS) which are nice to have if you get decent ones. A low profile gas block under the handguards is better.

-Mil-spec/M16 bolt carrier - A proper milspec BCG has more steel at the rear of the bolt carrier than some non-milspec ones sold by lower end companies. Milspec is more reliable because of this extra weight and also correct dimensionally.

-MPI tested bolt *- Magnetic particle inspection tested. You want to buy from a manufacturer that does individual MPI testing of each bolt they make. Because of the complex shape of the AR15 bolt and the steels used small flaws in the steel can result in rapid failure of the bolt, inside a couple of hundred rounds. Individual MPI testing ensures that you don't get a bolt with these flaws. It's a quality control and failure prevention thing

-Properly staked gas key screws - The gas key is the part of the bolt that the gas pushes on to work the action. Staking is a method of securing screws so that they don't come loose. Gas key coming loose = bad

-General quality - If you buy from a lower end manufacturer you're more likely to end up with problems of things being out of spec dimensions, as well as lacking the above features. Pin holes in the lower being incorrect dimensions or in the wrong place, threads not straight, lower parts kit parts being out of spec, etc. Another problem with lower end manufacturers is that the picatinny rail on the upper receiver (or your handguards) tends to be out of spec which can cause accuracy problems and mounting problems with your optic. Lower end manufacturers of things like handguards tend to be heavier and weaker than better ones. More money = more quality control.

-Stay away from piston systems - The AR15 was designed as a direct impingement rifle, it works perfectly well as designed if you have quality parts etc. Piston systems are a stick-on bandaid for a problem that doesn't really exist, and they cause their own problems - carrier tilt leading to very rapid wear of the buffer tube, poor accuracy, etc. Especially any you're likely to see in NZ, as they'll all be lower end ones.