AR 18" vs 16"

[LiveLife]

I have 20" HBAR (1:9) and 16" ARs (1:7).

Curious about PSA 18" (1:7) upper - http://palmettostatearmory.com/psa-...lde-1-7-stainless-moe-upper-no-bcg-or-ch.html

For plinking to 100 yards, does 18" barrel offer significant accuracy increase over 16" barrels?

 

[badkarmamib]

You won't see an accuracy difference in longer barrels, just velocity increase. Within 100 yards, the flatter trajectory will be negligible.

 

[Browning]

Like he already said, at 100 yards ... No, you won't see any difference. Just an increase in velocity.

That's the velocity.
http://www.sadefensejournal.com/wp/?p=1093

Shorter barrels aren't less accurate anyway.

 

[M1key]

Wylde chamber. Should be a shooter. I don't know of any 16s with that chamber.

M

 

[Paul7]

Less noise than a 16".

 

[yugorpk]

Wylde chamber. Should be a shooter. I don't know of any 16s with that chamber.

M

Plenty of 16" Wylde chamber barrels out there .

 

[Jackal]

You gain a few fps. Thats about it.

 

[Walkalong]

significant accuracy increase

A match quality 16" barrel will out shoot the average barrel, regardless of length. Buy a better barrel, not a longer one, unless you want the velocity increase as well.

That average PSA barrel may or may not out shoot what you have now, but it won't be a length thing.

 

[M1key]

OP: I looked at that one myself, but I have a few 20s, so not much of an advantage other than the cost and availability right now. Most of their uppers and kits are stainless. Maybe folks aren't buying them. Still on the wait list for one of their CHF pencil barrel ones.

M

 

[Crunchy Frog]

I have a PSA .223 Wylde 18" barrel. One advantage is that is has a rifle length gas system.

 

[Tirod]

Gas length isn't that good to play around with. Port location is timing and early or late ports affect the cycle of the bolt.

An 18" barrel requires intermediate gas length - IIRC Noveske was one of the first to offer it. Since port location is measured back from the muzzle then having it timed for the bullet exit is how it's determined. It's also why midlength was invented - carbine gas meant for a 14.5" barrel is too harsh for a 16". The industry did it to lower the number of customer complaints and returns.

For every "advantage" one might tout in having the wrong gas length there is a corresponding disadvantage that has to be compensated for. In the case of having the port located toward the muzzle further than necessary the makers increase the port size which adds more gas volume - not pressure - to get the bolt to open - late in the bullets dwell time.

Taking it to an extreme Colt experimented with dissipators which had the muzzle directly after the front sight/port - and that didn't work out reliably. It was abandoned.

Barrel makers will make anything - but just because they can doesn't mean you should.

 

[agtman]

For plinking to 100 yards, does 18" barrel offer significant accuracy increase over 16" barrels?

(Re)-focusing on what the OP actually asked us, ...

... the clear answer is No.

For "plinking" at paper at 100yds, you won't see a "significant accuracy increase" with the 18" tube versus the 16" tube, unless there's something defective about the latter.

 

[LiveLife]

Thank you for your comments!

You definitely satisfied my curiosity about 18" barrels.

I am happy with groups I get with 20" HBAR as I use it for accuracy testing platform for load development but will consider 16" barrels over 18" on future builds.

 

[Llama Bob]

You won't see an accuracy difference in longer barrels, just velocity increase. Within 100 yards, the flatter trajectory will be negligible.

This.

Barrels in general become LESS accurate as they get longer - the rigidity of the barrel decreases as the cube of the length if I remember right. So if you make a barrel 10% longer, it's 33% more flexible.

 

[351 WINCHESTER]

Some of my most accurate rifles were actually carbines. I believe it has to do with barrel whip and a little dwell time.