What's the point of a 20" barrel anymore?

[Jericho941]

In an AR, that is.

Maybe it's just my self-destructively contrarian nature rearing its ugly head, but while SBRs are all the rage, I kinda want an M16-sized AR. I'm not married to the concept, but the desire is there. I just don't have a valid excuse. I mean, theoretically there's sight radius, but I also want to put an Aimpoint on it so that's not really an issue.

[Cobar]

I would think velocity, but I don't have the numbers to say if you get more with a 20" barrel, or if it would matter.

[JAG2955]

My longest AR barrels are 16". And I rarely shoot those anymore. But of course, my wife stole my 11.5" 5.56 SBR, so either I have to find funds to build another, or be willing to swap uppers with my .300BLK SBR.

A few years ago, I built what I called an M16A2.5. It's a 16" barrel, mid-length gas system with a Magpul fixed rifle stock, grip, and handguard. Flat top upper receiver, but I cut down a carry handle into an LMT-style rear sight. It also wears an Aimpoint PRO most of the time.

Of course, I still haven't shot it.

[Rumpshot]

My longest AR barrels are 16". And I rarely shoot those anymore. But of course, my wife stole my 11.5" 5.56 SBR, so either I have to find funds to build another, or be willing to swap uppers with my .300BLK SBR.

A few years ago, I built what I called an M16A2.5. It's a 16" barrel, mid-length gas system with a Magpul fixed rifle stock, grip, and handguard. Flat top upper receiver, but I cut down a carry handle into an LMT-style rear sight. It also wears an Aimpoint PRO most of the time.

Of course, I still haven't shot it.

Ya need to plan a trip to Arizona this fall and visit Rumpshot's Revenge. Then you will have NO excuse not to shoot it.

[JAG2955]

My longest AR barrels are 16". And I rarely shoot those anymore. But of course, my wife stole my 11.5" 5.56 SBR, so either I have to find funds to build another, or be willing to swap uppers with my .300BLK SBR.

A few years ago, I built what I called an M16A2.5. It's a 16" barrel, mid-length gas system with a Magpul fixed rifle stock, grip, and handguard. Flat top upper receiver, but I cut down a carry handle into an LMT-style rear sight. It also wears an Aimpoint PRO most of the time.

Of course, I still haven't shot it.

Ya need to plan a trip to Arizona this fall and visit Rumpshot's Revenge. Then you will have NO excuse not to shoot it.

Well, I'm much closer now.

And don't ask how many rifles I have that I haven't shot yet.

[SoupOrMan]

For me?

Slightly longer sight radius, a little more speed, and nostalgia.

My FUDD-15 in 6.8SPC has a 20" barrel mostly for velocity purposes and is still awaiting wood furniture (and the needed butchering of the handguard to fit a free-float sleeve). Honestly, it wouldn't look right with a 16" barrel so there's also an aesthetic purpose.

[Weetabix]

And don't ask how many rifles I have that I haven't shot yet.

I can only think of 5 in my safe(s) that I haven't shot. They're all old milsurps that caught my eye for a good price, though. I don't have any builds.

[rightisright]

I have an older 20" Bushmaster HBAR A2. I rarely shoot it anymore because it is irons only and my eyes have gone to shit in the last few years. It is, however, amusing to see how "old" it looks next to the M4geries.

[BloodlessWeevil]

I would think velocity, but I don't have the numbers to say if you get more with a 20" barrel, or if it would matter.

These guys have numbers:
http://www.ballisticsbytheinch.com/223rifle.html

Check out the muzzle energy graph. It seems that muzzle energy for the loads tested increases linearly up to 18 inches. Unfortunately, longer barrels were not included in the test.

[Netpackrat]

If I had to use 5.56, I would want a longer barrel.