Most Popular Barrel Length for 6mmARC?

[6mmAR]

I have a bunch of Bartlein 6mm 5R 7.5 twist 5R blanks and I am going to make up a bunch of 6mm ARC chambered barrels and I am curious what people feel is most popular for a barrel length in the 6mm ARC - - I am thinking 20" because it strikes the balance between being carryable and maneuverable, yet long enough to get a decent velocity out of the cartridge.

For the off the bench shooters and varminters we have done a lot of 24" 6mmAR's, and I am sure there will be some demand for that length out there, but I am not sure that's the most popular.

Opinions on what would be the most popular for barrel length?

[danm]

I'm gonna say 18"... Only because that's what I have and it seems that's the length it was supposedly designed around?

[StoneHendge]

What sort of barrel life have you seen. You're probably the one who knows best (aside for the US military, who ain't gonna tell us squat). Maybe in terms of when that 1/2 MOA goes to 3/4, and then when it breaks MOA.

[6mmAR]

What sort of barrel life have you seen. You're probably the one who knows best (aside for the US military, who ain't gonna tell us squat). Maybe in terms of when that 1/2 MOA goes to 3/4, and then when it breaks MOA.

If one is doing a lot high capacity rapid firing, that can really kill a barrel.  In the high-power competitions which was a balance of rapid fire and slow fire shooting, I typically saw between 2500 - 3000 rounds of highly accurate barrel life.  Most of the re-barrels for customers came in after around 3000 rounds.

[6mmAR]

I'm gonna say 18"... Only because that's what I have and it seems that's the length it was supposedly designed around?

Hmmm - - You may be and probably are right, but I doubt one will achieve the touted 2750 fps out of the Hornady "Black" 6mm ARC ammo with the 105 gr bullet out of that length barrel.  FWIW I also doubt one would get there with my suggested 20" barrel either.  With my work with the 6mmAR, we found that velocity seemed to peak around 25", although there was very little increase between 24" to 25".  The proven method for determining this was by taking a couple 28" barreled uppers and a hack saw with a hand crowning tool with the chronograph (as well as plenty of weighed charges ammo) to the range and chronographing 5 shots, then saw and inch off the barrels, then go again, then saw and inch off, etc.  That method really gives true data on barrel length vs velocity.

[grayfox]

I got mine as a 20”, for the basic reasoning you mention. It’s also rlgs which is doing fine.
However for a top-tier barrel maybe 20” is the min I’d think...?
The 105 black I’ve shot get, 2665; it’s early and my brain is not awake yet. The 103 eldx loads I can get 2700 with lever but for now my node seems to be 2681. But it’s mainly intended for hunting not competition.

[StoneHendge]

What sort of barrel life have you seen. You're probably the one who knows best (aside for the US military, who ain't gonna tell us squat). Maybe in terms of when that 1/2 MOA goes to 3/4, and then when it breaks MOA.

If one is doing a lot high capacity rapid firing, that can really kill a barrel.  In the high-power competitions which was a balance of rapid fire and slow fire shooting, I typically saw between 2500 - 3000 rounds of highly accurate barrel life.  Most of the re-barrels for customers came in after around 3000 rounds.

Thanks! When they get replaced is the best indicator there is, and figure it probably takes a bad match or 2 to determine the barrel is the problem.

[JASmith]

Three barrel lengths come to mind.:

1) Primarily target — 24” to 28”
2) Mostly hunting with some target - 18” to 20”
3) 16” (Yes SIXTEEN) if lugging around the field and hills for hunting with rare competitive target shooting.

[danm]

I'm gonna say 18"... Only because that's what I have and it seems that's the length it was supposedly designed around?

Hmmm - - You may be and probably are right, but I doubt one will achieve the touted 2750 fps out of the Hornady "Black" 6mm ARC ammo with the 105 gr bullet out of that length barrel.  FWIW I also doubt one would get there with my suggested 20" barrel either.  With my work with the 6mmAR, we found that velocity seemed to peak around 25", although there was very little increase between 24" to 25".  The proven method for determining this was by taking a couple 28" barreled uppers and a hack saw with a hand crowning tool with the chronograph (as well as plenty of weighed charges ammo) to the range and chronographing 5 shots, then saw and inch off the barrels, then go again, then saw and inch off, etc.  That method really gives true data on barrel length vs velocity.


Yeah just doing my drop at 525 yrds 3.4-3.5 mils I'm calculating 2650 Proof 18" Carbon.... Don't have a chrono, I know... Tisk tisk. I don't reload yet but plan to eventually and obviously save all my brass... Got a ton of Grendel and 40 6ARC so far.....

I got mine as a 20”, for the basic reasoning you mention.  It’s also rlgs which is doing fine. 
However for a top-tier barrel maybe 20” is the min I’d think...?
The 105 black I’ve shot get, 2665; it’s early and my brain is not awake yet.  The 103 eldx loads I can get 2700 with lever but for now my node seems to be 2681.  But it’s mainly intended for hunting not competition.

[Biodsl]

Robert...I thought this might be helpful: here's a poll on barrel lengths from the Grendel Forum. Many of us here are Grendel owners so this might provide insight into preferences.  Only 23% of owners who responded have Grendel barrels over 20" 

https://www.65grendel.com/forum/showthre...ndel-AR(s)

[6mmAR]

Robert...I thought this might be helpful: here's a poll on barrel lengths from the Grendel Forum. Many of us here are Grendel owners so this might provide insight into preferences.  Only 23% of owners who responded have Grendel barrels over 20" 

https://www.65grendel.com/forum/showthre...ndel-AR(s)

Thanks - it seems like the most popular is 20", followed by 18", followed by 16".

[JASmith]

Robert...I thought this might be helpful: here's a poll on barrel lengths from the Grendel Forum. Many of us here are Grendel owners so this might provide insight into preferences.  Only 23% of owners who responded have Grendel barrels over 20" 

https://www.65grendel.com/forum/showthre...ndel-AR(s)

Excellent onfo. . . . but wth the inevitable “however” - - -

Grendeliers tend to be hunters with a fair bit of lugging around in the woods with a few home defenders in the mix  These drive folks to ahorter barrels.

My sense is that “Arcers” will tend more to long range competitive target shooting.  This emphasizes the longer barrels and “lugging around” is not as much a driver.

[Chev2500]

In 6.5 Grendel AR's I have 18 & 20. My first arc will be a 16 for use with a suppressor.
For me velocity will be secondary , I have 243 AI, 220 swift, 22 Creedmoor in bolt guns for speed.

[Devildog6mm]

I can’t speak for the best length, but I am waiting on my 21” Odin barrel. Seems like the perfect length for it. I use 20” Grendel barrels and love them.

[drewthebrave]

Robert...I thought this might be helpful: here's a poll on barrel lengths from the Grendel Forum. Many of us here are Grendel owners so this might provide insight into preferences.  Only 23% of owners who responded have Grendel barrels over 20" 

https://www.65grendel.com/forum/showthre...ndel-AR(s)

FWIW, that poll started in 2014 and the most recent reply was from 2018.  In the past few years, I've seen a pretty dramatic uptick in the popularity of 12" to 16" barrels for the 6.5G -- likely as second or third builds as truck guns or suppressor hosts.  I think the preferences for 6mm ARC will initially skew a little towards the 18+" end of the spectrum, but I wouldn't be surprised to see shorter barrels become very popular as well.  With the high BC of 6mm/.243" projectiles, an 11.5-14.5" 6ARC could be the perfect do-everything gun to fill the role of most 16-18" 5.56 Recce/SPRs.