Pairing down, if you can only keep 3 ARs.

[Erni]

Hi folks,
I have decided that I just need to pair down the stable of ARs, get rid of a few, keep only three. I never shoot most of them, but thought I would pair it down and just concentrate on the following:
1. Light 16" gun: standard m4 type barrel minus the launcher cut, with light free float handguard, BUIS, MOE furniture, needs a light RDS to be complete
2. Medium 16" gun: RRA heavier profile barell (not bull/varmint), needs a lighter free float handguard, some furniture updates, and has a 1-4 Millet. (not seksy but very accurate)
3. Heavy 24" gun: 24" SS barrel, round free float handguard, A2 stock, flat top reciever, currently sporting russian glass with a german post reticle (scope sucks for parallax needs updating)

What wold be the three you keep? Any sugestions on the 3 gun setup I created?

[MarkCO]

Lightweight 16" AR, 5.56 chamber, NiB coated BCG, simple flash hider, simple RDS or laser and BUIS, maybe 6 pounds or so.

Medium 18", .223 Wylde Chamber, 1-4 or 1-5 optic in one piece mount, carbon fiber HG, low mass BCG, comp.

Heavy 20", .223 Wylde Chamber, 3 or 4 x on bottom to 12 to 20x on top, threaded for suppressor, Seekins flat bottom HG, standard carrier with enhanced bolt.

[Great-Kazoo]

The 3 you shoot best.

[Erni]

@MarkCO, curious why 20" vs longer on the heavy?

Yarg!

[MarkCO]

@MarkCO, curious why 20" vs longer on the heavy?

Yarg!

The longer the barrel, the thicker it needs to be to maintain accuracy. On a gas gun, ALL of the barrel mass is hung on aluminum threads with varying degrees of tolerance. Even with a shimmed, or thermal fit barrel torqued above 75 ft-lbs, you will get some thermal drift. The 20" barrels minimize that effect due to less leverage on the threads. The increased accuracy is more important to me than 100 fps of velocity.

I built identical Kreigers, and the 20" had less drift of the POI as compared to the 24". Both shot very small groups, the 24" just walked them around a little bit more based on ambient temperature and the barrel temperature.

Not saying a 24 is bad at all and depending on what you shoot and how, the 24 might offer some benefits over the 20. For me, the 24 does not provide me any benefit over the 20.

[68Charger]

I'd say because off-the-shelf ammo won't gain velocity with more than 20" of barrel...
You generally have to reload with slow-burning powder to take advantage of a 24" barrel in .223/5.56
Since you said ARs, make the Heavy an AR10/LR308... .308 can take advantage of a 24" barrel, and is better suited to >400yrd

if sticking with AR15s, why not take advantage of the modularity of the platform and go with 2 lowers (one light, one precision), and maybe 4 uppers (at least one in an alternative caliber)

[Erni]

Curious as how you arrived at thermal drift vs whippiness of barrel.
An AR10 will be a future decision, plus I like my FAL. ( I realize the fal is less accurate and has faults but its a FAL!)

Yarg!

[MarkCO]

Curious as how you arrived at thermal drift vs whippiness of barrel.

Lots of testing is the bulk of it. When the barrel heats up and the group sizes are the same, but the center moves, that is one indicator. Temperature measurements combined with the metallurgical properties and vibration analysis is another indicator. Inductive heating of the chamber alone, and seeing progressive change in POI due to the heat transfer is another indicator.

[Chad0724]

I only have 1

[vectorsc]

I wouldn't go with 3 - Id do exactly what I do now.

Best SBR lower you can build +
20" Match Upper
9" 300 Blackout Upper

Swap accessories depending on what is needed at the time. That way you get every benefit of being short and every benefit of being long. And you can afford the better toys like surefires and aimpoints and such because it's only 1 gun.