I have a Colt 6940 LE M4, with a monolithic quad rail. Is it possible to put a longer quad rail on the upper receiver of the rifle? I am not sure if it is being that it appears that the quad rail itself and the upper is one stand alone piece. With that said, are there other options to extend the length of the rail system such as some kind of extension? Feedback is greatly appreciated. Many thanks.
No, you cannot.
C4
While monolithic uppers have some unique benefits, the two very prominent negatives are lack of modularity and typically increased weight.
I have never understood why monolithic uppers are heavier than their modular counterparts. It seems that they could be lighter since you don’t have to use any mounting hardware/fasteners. I’m just spitballing here. Not sure if that makes sense.
My guess is do to the purpose in which most monoliths are built, increased accuracy through rigidity and harmonics, in which case weight is considered a friend, not foe.
Nope…you cannot change it.
I too have a 6940 and have just learned to like it and live with it. I got an insane price on this one (around a grand) so I could not pass it up. The thing is so accurate…I just pretty much learned to work around the shortness of the front section.
I actually like the 6940 - mine is accurate and eats anything I throw in it.
The only way to extend it is to replace it with another upper. Sell the complete mono upper to someone who thinks it is more accurate. Plenty of people drink the mono cool aid.
I like the idea of a monolithic upper for an SBR simply because I think it would be stronger and the purpose of an SBR is CQB. Think Noveske Diplomat.
Since I do not have really long arms, I was able to adapt to the 6940’s rail system pretty easily.
The 6940 gets no love around here…I get that. If I had longer arms…the short quad rail would drive me nuts as well.
However if you have shorter arms…give it a try. God knows my 6940 is reliable and pretty damn accurate.
I don’t think it has anything to do with weather you have long arms or not, I’m 6ft 2in tall with long arms and I have no problem with the short rail on the 6940. I think where the problem lies is if the particular user is a practitioner of the Costa fad hold and the guys that like to play fad rail of the month.
Of course there are the midlengthers that just don’t like anything that has a carbine length gas system, midlengthers are usually also big fans of the Costa fad hold as well.
Bottom line: The 6940 is a completely useless boat anchor for it’s complete lack of Keymods or M-Locks, or if not that, because of it’s inability to settle the debate between the two.
So it sucks because of its lack of being able to be trendy? LOL
Perfect…I’ll keep on shooting it.
That’s right, a lot of guys just love to stay up to date with the latest AR fashions.
That means more 694X’s for those of us who appreciate them!
I had one and it was a .5 inch gun. Sold it. I just recently bought the 6945, which is the 10.3 barrel. I do like it. I have non mono uppers and mono uppers. I dig both and suggest buying both, good diet of AR’s keep a man healthy.
Yes, my current stable of ARs is a 6920 and the 6940.
After handling one…I now want to add a 6720 lightweight to the mix.
Damn these ARs…they are multiplying like 1911 and Mausers around my place! LOL
Like others have said, you can’t change it. But the good side is it’s a great gun you’ll be able to get plenty of trigger time with. Low profile rail covers and you’re set.
The 694X series make fantastic SBRs. Mine will soon wear a 11" barrel.
How much longer do you want to go? Would you replace the FSB with a low gas block or go around It?