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9/22/2017 12:11:25 AM
Posted: 9/25/2005 6:58:18 PM EDT
Or would I have to put one together ?
Link Posted: 9/25/2005 7:23:30 PM EDT
check out model 1 sales. they have several different models and options listed. www.model1sales.com
Link Posted: 9/28/2005 11:01:05 PM EDT
PRI makes a complete mid-length upper for around $1300.
Barrett's M468 upper half runs $1600.
Short of that, I can't think of any 6.8 Mid-length uppers off-the-shelf.
I custom make 6.8 barrels and most guys are ordering them with mid-length gas systems.

Randall
Link Posted: 9/29/2005 7:07:03 AM EDT

Originally Posted By Randall_Rausch:
PRI makes a complete mid-length upper for around $1300.
Barrett's M468 upper half runs $1600.
Short of that, I can't think of any 6.8 Mid-length uppers off-the-shelf.
I custom make 6.8 barrels and most guys are ordering them with mid-length gas systems.

Randall



Not to derail this thread, but what is the point/advantage of a mid-length gas system?
Link Posted: 9/29/2005 7:25:22 AM EDT

Originally Posted By yankee2:

Originally Posted By Randall_Rausch:
PRI makes a complete mid-length upper for around $1300.
Barrett's M468 upper half runs $1600.
Short of that, I can't think of any 6.8 Mid-length uppers off-the-shelf.
I custom make 6.8 barrels and most guys are ordering them with mid-length gas systems.

Randall



Not to derail this thread, but what is the point/advantage of a mid-length gas system?



Smoother operation. The carbine gas system operation is harsh, for lack of a better term. The rifle system is very smooth and the midlength is pretty smooth also.
Link Posted: 9/29/2005 7:49:43 AM EDT

Originally Posted By mongo001:
Smoother operation. The carbine gas system operation is harsh, for lack of a better term. The rifle system is very smooth and the midlength is pretty smooth also.



As usual, Mongo hit the nail on the head.

More info about gas systems here:
www.ar15barrels.com/prod/gas-systems.shtml

Randall
Link Posted: 9/29/2005 10:39:57 AM EDT
Thanks Randall & Mongo...I've lurked here enough to know that you guys know your stuff !
Link Posted: 9/29/2005 7:03:57 PM EDT
OK. Krafty got what he wanted to know, but I'm still partially in the gray. OK - shorter gas tube/system (are the orifices different, or just the gas tube lenght??) equals "harsher" operation. Because of? Shorter tube? Higher gas pressures (shorter lenghth of barrel from chamber to gas bleed off orifice)? Is the latter the only way to avoid "harsh operation"?

Finally, is the military using mid-length gas systems?
Link Posted: 9/29/2005 7:05:00 PM EDT
Shorter gas tubes have higher pressures.

The military is not officially using any midlength systems.
Link Posted: 9/29/2005 8:10:13 PM EDT
With the 6.8 being a lower pressure load than the 5.56 already, I dont see the need for a mid length. Other than maybe a longer handguard/mounting platform.
Link Posted: 9/29/2005 8:52:59 PM EDT

Originally Posted By Timanator:
With the 6.8 being a lower pressure load than the 5.56 already, I dont see the need for a mid length.



I have to disagree with this statement.

I have it from a very good source that the first Remington 6.8 SPC ammo was running over 70,000 PSI when they warmed it up to 130 or 140 to simulate storage in the desert much like ammo the boys in the sandbox might be using.

This is the reason the new ammo is loaded to lower pressure/velocity now.

The more distance you put between the chamber and the gas port, the better PERIOD until such time that you don't have enough barrel past the gas port to get good function.
Keep 5" of barrel out in front of the gas port and all is well.

Randall
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