Posted this on another forum, but wanted to share here as I have been reading a lot here lately. Just wanted to show a few pics of Colt’s 6940 and 6940P uppers next to each other. I picked up a 6940P last April, but due to travel I have not gotten a chance to shoot it yet. After handling it though, I must say I fell in love with Colt’s monolithic design. It just feels perfectly balanced when I shoulder it. So, I began looking for a regular 6940 upper, and a few months ago found one for sale. I am going to put it on my M4 Sporter lower. The two biggest complaints against the 6940 seem to be the inability to replace barrels, and the short length of the hand guard. Neither of which bother me at all. I really do not use rails too much anyway, and I have plenty of other “home grown” AR’s if I want to swap stuff around every month. One of the reasons I like the 6940 series is that I have heard nothing but excellent results in the accuracy department. Some day I will get both of the uppers to the range and see how that goes. All in all I am pretty impressed with how nicely “packaged” the Colt piston seems to be. They did a great job integrating it into the monolithic platform. Hopefully this week I can pick up a scale and compare weights. Thanks for looking
The lower:
Piston on bottom:
Gas blocks (piston on top):
Piston on bottom. It has a SOCOM barrel with flats, dated 04/13. The regular 6940 is Gov. profile dated 09/13
The piston:
Front view of gas block:
Piston and gas tube - receiver view:
Cam pin wear plate. Both receivers have this:
BCG’s. The piston BCG has a chromed line bore, is one piece, and has gas rings on the bolt:
BCG’s top:
BCG’s bottom:
Piston “anti tilt” on right:
Piston BCG:
Complete piston rifle. Added a TA31H-G, KAC micro rear and Magpul MOE. Going to find a standard A1 grip, my favorite
It does not feel like much, but I can discern it. Not sure if it is the piston or the heavier barrel, but I feel it there. I have an LMT SOPMOD in storage, think it would reduce the front heaviness. If I just bring it up to my shoulder ‘easily’, and look through the sight I notice a front end tip. I am going to try to pick up a postal scale this week, as the T&E guy in me really wants to know the weights. If I put both uppers next to each other and pick them up, it is easy to sense a difference. That’s why I want to try a heavier stock.
Nice photos. I also have a 6940 and have been thinking about adding the 6940P to the collection. Keep us updated on how it functions.
Like you I have other AR’s. So the monolithic platform and “fixed” barrel wasn’t a big problem. I have a couple piston driven AR’s in the collection and thought the Colt might fit in too. Just couldn’t find one to see up close. Your photos helped.
I have one of each of those and was interested to see the differences between my earlier generation 6940 and your current one. Mine doesn’t have the front sight lock or cam pin plate. I was wondering if the SOCOM barrel on my new 6940P was now standard on the 6940, but I guess not. As for a range report, they are both utterly reliable. Both are running A5 buffer systems and BAD-CASS safeties and pin sets. The 6940 is on an Aero ambi lower now since I bought it as an upper only back in 2010. Sometimes I get some insanely tight groups out of them, despite using regular old XM855. My personal best was a cloverleaf at 50 yards while zeroing irons in. One of these days I will drag out the Hornady and Black Hills ammo I have tucked away and see how it does with that.
I had my 6940P barrel reduced to standard M4 profile under the handguards and cut to 14.7" with FH perm-attached by ADCO. Makes a big difference in heft; doesn’t feel much different than a 6920 to be honest.
Any noticeable change in accuracy with the lighter profile barrel? I know Colt is using sort of a ball and socket affair on their piston rod that’s supposed to allow the parts to flex when the system gets hot. I’m curious as to how well that works in practice.
Not that I noticed with an Aimpoint T-1. The “swingability” from point to point is noticeably smoother though.
I don’t have a lot of rounds through it so it’s not like the ball-socket on the piston rod has been through a Pat Rogers carbine class or such. I got ahold of Colt when the newer one-piece carriers came out (the original was the solid keyed one). I requested the new carrier as well as the longer op-rod needed to reach the nub on it. Not only did they send me the new carrier and op-rod I had requested (at no cost), but a few weeks later I got yet another package from them with a second carrier, op-rod, and piston! Must have been a SNAFU on their behalf. So I now have a complete spare parts setup (no second bolt though :rolleyes:).
ETA—I took the “old” style carrier and removed the solid key and replaced it with a regular DI one from Bravo Co. along with the screws. So I then had a spare DI carrier too.
I realize that. I just prefer the extra couple inches of barrel (being out here in the Boondocks). Never really been a SBR fan,but that’s just my preference.
