I am thinking about putting together a lightweight 6.8 pistol upper for deer hunting and would like to keep the barrel length around 10.5".....any recommendations on where to find a lightweight 10.5" 6.8 spc II barrel?
Thanks

ar performance has a 12.5 light weight in 6.8  on sale for 179.00 right now

Thanks but really looking for a 10.5" if I can find find it.

sorry....double post

For 6.8 your not going to find a better barrel than the one suggested above.


12.5 is the sweet spot for short barreled 6.8.





 

Bison Armory has 8.5" and 11.5" barrels.  If I recall correctly Bison pretty paved the way to the short 6.8 barrels.  I have owned several of their longer barrels and they all shot very well.
Bison

Thanks guys....

What he said....

What performance are you looking for?
12.5" is the sweet spot with 6.8.

Check mad dog weapon systems he had some 10.5" barrels

Does anyone have a link to a chart listing the velocity loss per inch of barrel for 6.8?

I built my 16" 6.8 a few years back after a two year schedule. In the day, it was common knowledge that the SF and AMU developed the 6.8 for the 14.5" barrel in the M4. That was the designed purpose.

Since then I've heard 16" was best, and now, 12.5" the "sweet spot," more than once. But nobody links or posts a report about testing, or charts. So, after looking for hours, I figure I'd ask.  

I've seen the report on 5.56, and why 10.5" was determined to be the shortest effective length, and used since 1966 as DOD's SBR. Being a 6.8 user, I'd like to see the same chart for it and where that sweet spot really is. I don't believe it's based on velocity, it's based on gas pressure same as 5.56 or .300BO. I expect it could be as low as 8" - after all, that;s what LWRC sold the Saudis on contract.

68forum is the oracle you seek. Many posts on 12.5" being the sweet spot for short barrels. A lot of hog hunters are using them.

I would go ARP 12.5". Be careful of the short bison barrels some are twisted for subsonic.

"Many posts" but none linked.

The OP wants a 10.5" barrel - it would contribute to the overall length falling under 26" and that can have a lot to do with it being a pistol.

Here's what ARP says: and yet what is described above is very nearly the same as what happens with the 5.56 when going from 16 to 10.5" and it didn't stop Colt in 1965. They accepted what would happen because the resulting weapon wasn't meant for long distance work, it's was about CQB and distances under 125m. The Navy does the same - shipboarding operations, which is also CQB.

We accept a 400fps loss with 5.56, it's not a major issue with 6.8 if you keep your engagement range down. Most of us understand that. Check the chart here: http://www.sadefensejournal.com/wp/?p=1093

Doubling the gas pressure for 5.56 is acceptable for almost anyone who builds a pistol or SBR, the goal is a SHORT barrel. The tradeoff is reduced velocity. There is no "sweet spot," it's basically what the shooter is willing to accept as a minimum performance threshold.

It's why some carry a 3.5" .45 ACP 1911 vs 5". Short barrel. They are also harder to tune with a much smaller window of reliable operation. It seems the smaller the better for the buying public.

5.56 is still effective at 10.5",.300BO comparable at 8", and 7.62x39 down to 9" with the Draco's. It's about volume which is determined by diameter and length.

There is a sweet spot for every caliber and barrel length. That is the length at which the FPS of the round drop off dramatically.



As you point out in your quote above the 6.8 looses 100fps going from 16" to 12.5" but 500fps at 8". Under 12.5 the 6.8 starts dropping velocity very quickly, therefore we call 12.5 the sweet spot, The shortest you can go without a major derogation of velocity and the accompanying loss of energy.



So yes there there is a sweet spot other than what the "shooter is willing to accept as minimum performance", which is simply your personal definition, not the shooting communities long recognized definition.



 

LWRC sold the six8, not the 6.8. The Six8 can be loaded a wee bit longer. It's a small change but has big effect on the round. Six8 lowers and uppers are not comparable with standard AR uppers or lowers and the PMags for the Six8 will not fit a standard AR magwell.
The 90gr Gold Dot round was also developed by ATK expressly for the short 8.5" barrel. All in all you can't compare the standard 6.8 and the Six8.
 

mad dog weapon systems had some 10.5 inch 6.8 barrels a few months ago but I don't know if they will ever get them again.

I picked one up for $99 and it has been a great shooter (although only at paper/steel so far).

The weird thing about them was they were a pistol length gas system so I was worried about function. So far mine has performed well for 200+ rounds with no cycling/feeding issues. Definitely a little dirty.

I also know that YHM sells a 10.5 inch 6.8 barrel so that is also an option. If I were you I would get the Bison 11.5 since it is available and a fair price.