Colt CM901 on DefenseReview, 308 platform that will also shoot a 5.56 upper

Quote:

Originally Posted by RAM Engineer

The CM901/SP901 does not use a carbine length gas system. Also how does a gas port that is angled back towards the origin of flow help "smooth out" gas flow? Have you ever seen any water pipes angled like that? Either way, that gas is going to have to make a 180 degree turn. Which is better, two 90 degree turns or a 135 deg turn followed by a 45 deg turn? Angled gas ports have other drawbacks as well, as evidenced by Russia's change from an angled gas port on the AKM series to a straight (90 deg) gas port on the AK74/AK-100 series of guns.

Here is where on this forum someone indicated carbine length:
https://www.m4carbine.net/showthread.php?t=66792&page=2

Where did you get the info that it is not carbine length? I hope you are correct.

As for angled versus 90, I have read (apparently in a different place than you have) that the reason why they went back to 90 was it was easier to make, some claimed it was due to bullet shear, but the dragunov retained the angled port. If this was low pressure flow, then I might agree with your worse turn angles idea. However, the pressure behind the escaping bullet is high, the port is the path of least resistance, hence gas will want to go into the port. Angling the port makes it even less resistance. Also, I think LMT copied this from KAC but not sure. I know KAc does it and KAC has been making 308 AR's longer than anyone else and continually improving on them over the last 21 years. LMT was involved with Armalite in bringing back the AR-10 in the mid 90's. I trust that both LMT and KAC having more 308 AR experience than any other company(except for Arma in LMT's case anyway) knows what they are doing in their latest designs. Besides you cannot compare a precision tool like an AR to an AK's piston system. Apples and oranges.

That is one difference between the LMT MRP and the MWS. MWS has angled port.

here is what LMT had to say on it:

Quote:

It should be noted that LMT drills their gas ports
into the barrel at an angle slanting back toward the
receiver from the bore line, giving the gas block a
distinctive AK profile. Engineers found that drilling
the port straight into the barrel led to gas erosion
on the rear edge of the hole, eventually letting
more gas into the port than the original design. By
angling the gas port and tube, the propellant gas
flowing behind the bullet enters the gas block at a
more natural, efficient angle.