Originally Posted by chris
:Looking for a AR-15 type weapon. Been reading about how the HK416 is better than the M4.
What do you thing about this weapon?
HK MR556 A5 Rifle in 5.56mm with 16in barrel in black.
Like the HK416, the MR556 is a major product improvement of conventional AR-type carbines and rifles. Using the HK-proprietary gas piston system found on the HK416 and G36, the MR556 does not introduce propellant gases and carbon fouling back into the rifle's interior, making it the most reliable of any AR-type firearm. The MR556 uses many of the assemblies and accessories originally developed for the HK416 series arms including the HK free-floating four-quadrant rail system/handguard. This system allows all current accessories, sights, lights, and aimers used on M4/M16-type weapons to be fitted to the MR556. The HK rail system can be installed and removed without tools and returns to zero when reinstalled. Like the famous HK416, the MR556 uses a barrel produced by Heckler & Koch's famous cold hammer forging process. The highest quality steel is used in this unique manufacturing process producing a barrel that provides superior accuracy for more than 20,000 rounds with minimal degradation of accuracy and muzzle velocity.
So here's a question(as someone who looked at the HK too), why do you think a gas piston system is better? Because marketing tells you it is?
So the DI versus piston discussion is a long one and in short the differences between the two are somewhat of a wash. One is not clearly better than the other. Maybe if you are shooting sustained full auto it's a bit better but it's not clear in the AR platform that it is.
Advantages to Direct impingement(i.e. the original design).
-supports any number of standard off the shelf custom forgrips/parts etc.
-tends to be a bit better accuracy in single shot(or that tends to be the claim)
-Gas is dumped in receiver causing more potential for fouling and a greater requirement to keep it clean
Advantages to Gas Piston
-Gas vents externally allows for a significantly cleaner action.
-greater tolerance for variations in ammo
-every gas piston is proprietary no parts interchange need custom handgaurds
-more (and complex) parts tend to be less reliable
-much more costly(because it's all proprietary)
Technically there's not a huge difference between the two, but the gas system will be more expensive and you'll have less customization options for your rifle. In exchange you get a cleaner action which will need less cleaning. If you put away your guns without cleaning then that may be an advantage. But for me no gun gets put away without being cleaned and oiled. So the extra cost buys me very little.
I went back and forth a long time to see if I wanted one but I ultimately decided no. If I want to add one later then I'm sure I can.
For me to add one later I want the piston attached to the bolt(so you have less bolt tilt and receiver wear) and I want it to fit under a Daniel Defense handguard.