[marathonrunner]

Hey Gunslinger, I have one of these too but if you can look inside your barrel extension, the area between lugs and chrome lining, do you see any signs of corrosion? I was a bit disappointed that I seen some brownish color but more like rust in the recessed area.

 

[marathonrunner]

Gunslinger, both my 6940's were never fired and both have rust in that part of the extension barrel. Called Colt and basically they told me that they consider that a minor imperfection. I can't understand how rust can be considered minor, especially that it is brand new

 

[marathonrunner]

Very sorry to hear you received sub-par Colt merchandise I have bought tons of colt items and everything I have bought has been nothing short of perfect

I will say for a battle rifle it's very good but cheap materials. i.e., carbon steel barrel strong but prone to rust. Carbon steel barrel extension, again prone to rust. I have learned there are better materials than "Mil spec" which really means bare bones. In other words there are a lot of stuff better made than Mil spec and from talking to many GI"s. they tell me they buy their own bullet proof vests because gov issue are junk. Looking back I would have bought the Wilson Combat. ie., the 6940 uses cheaper 4050 aluminum where wilson uses premium 7075. also wilson uses stainless steel for barrel. But I still like my Colt and will hang onto them.

 

[marathonrunner]

Colt does not use 4050 aluminum anywhere. They use 7075 T6 Type-III hard coated aluminum for the upper and lower receiver, and are one of the only companies to use a proper extruded 7075 receiver extension.You may be getting confused on the barrel which is 4150 CMV(probably the best barrel material for a combat rifle).To the OPOptic: Trijicon SRS02 is by far my favorite.Foregrip: so many out there its all up to you.Bipod: I usually do not use one as I just mono it from the magazine.Laser/light: ignore the laser, they generally have a visible range of 20yards so unless running lots of NV they are pointless. For the light the XM300 is a great option, its light small and easy to use when your thumb.Magazine: i use Lancer AWMS, they feature a hardened steel wraparound feedlips that are near impossible to break, feature a constant internal curve designed for the taper of the 5.56, and are very durable.

Hey Olgee, thanks for setting me straight! I guess me being a noobe I don't know too much. But let me ask you this, in a perfect world, if money was no issue for the US Military, wouldn't a stainless steel barrel with chrome lining offer the best of both worlds? What if the barrel extension was also chrome lined? Why did they leave that unfinished, thus exposing it to rust? Anyway, maybe you can answer this question. Have read many articles saying never use a 3 piece cleaning rod or else you can scratch the barrel. On the 6940 chrome lined barrel would that same thing apply? Could a chrome lined barrel get scratched by an aluminum rod? Anyway here is more interesting things about the AR-15 and flex. I found it on another forum and a guy tests the gun for flex by adding weights to the end of the barrel. Said the A2 carrying handle offers the stiffest while the removed flattop actually weakened it. Part 1 and II

Upper Receiver Flex Testing - Part One - M4Carbine.net Forums
Upper Receiver Flex Testing - Part Two - M4Carbine.net Forums

 

[marathonrunner]

The A2 handle provides extra rigidity to the upper. Its not a material difference as far as material type but by removing the carry handle you remove material which will make it slightly weaker. That said the trade off was worth it in the modularity department.

The Chrome Lining was added to barrels for a few reason. Fisrt it increases barrel life, it helps reduce corrosion, and it helps in extraction. But it does slightly reduce accuracy

As a current civilian I can choose whatever barrel I want and stay with 4150 CMV. The issue with SS is heat affects it more than 4150 steel. It is softer which helps make a more uniformed and correct bore when they button rifle it, but because it is softer it does not handle abuse and heat as well. This will lead to shorter life than a 4150CMV barrel as each bullet reduces the rifling.

SS barrels are generally used in DMR's such as the L129A1(LMT 308MWS) as a designated marksman rifle will not see high volumes of fire.The increased hardness of 4150CMV gives it far greater life than SS but at reduced accuracy because the rifling will not be as clean since they are harder and the metal is affected differently when button rifled. Now 4150 barrels are still 1MOA barrels but SS can be .25MOA barrels if you get a good made one.

I personally like to avoid cleaning rods unless they are polymer. Alot of people jam them in which bends them and causes them to scratch the chrome lining greatly reducing accuracy. If used correctly they are fine but far to often they are not use right.

Olgee, what about cleaning? Found tons of expert shooters that cannot agree on any one method. Some say use copper brush, others say no way. Still others say don't allow it to leave muzzle, etc.. But that was pertaining to SS barrels. What about chrome lined like mine? Will a 3 piece cleaning rod if it catches on the throat scratch it? hmmm

 

[marathonrunner]

The only thing you need to clean a CMV barrel is a bore snake(do not get the viper). A couple of passes fown the bore will get it as clean as it needs to be.If you use a cleaning rod you should always go breech to muzzle this will protect the crown as best as possible.

Hey Olgee, I just bought Hoppes Boresnake but pulling the damn thing through requires a lot of effort. Am wondering if by chance it can cause Point of aim to change, possibly permanently.

 

[marathonrunner]

No all you are doing is pulling 2 bronze brushes down the bore, its harmless.

actually I did a test using dumbbells and it took 30 lbs to pull the snake through. Ouch! In that link above where a guy hangs a 20 lb weight to the front stock, there was flex at the reciever and front muzzle but came back after doing it. But I have watched utube videos of muzzle breaks causing barrel to whip like a noodle so now realize bore snake there is no way that could tweak it. oh well