Posted: 9/17/2012 7:00:46 PM EDT
| i went to the range with my mk18 i just put together. it ran flawlessly with mil-spec 5.56 and steel case lower power ammo. i found it odd because when the rifle had the 16" lw barrel on it, it would not run anything but 5.56 reliably. i kept the h buffer in the sbr that came with rifle when it had the 16" barrel. i did notice when i was cleaning it today there was some wear on the casing deflector that was not there before. if you are looking square at the face of the deflector i guess that would be at about around a 45 degree angle in relation to the receiver, the ejection port being to the right, the first square edge on the deflector to the left of the ejection port is getting hit by the casings and wearing the finish off. is that an indication of anything that might need to be adjusted? i was wondering if maybe i need to go up to a h2 buffer? i just find it strange that the gun would not run weaker ammo with the original 16' barrel and now it will with the 10.3" barrel. and according to the dd website both barrels are supposed to have the same size gas port. any thoughts? |
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The gas port diameters are different sizes. Our 16" barrel gas port diamters vary between carbine and midlength gas systems. Our 10.3" barrels have a gas port diamater of appx .081" This may seem rather large to some, but we spent a lot of time testing barrels with multiple gas port diameters and various ammo and this is the sweet spot we found. With the majority of commercially available ammo being 55 grain .223 Rem, we wanted our MK18s to run reliably with the widest range of ammo possible. Different ammos are certainly going to perform differently. Some will eject harder and faster than others, but as long as it goes bang consistently, there is nothing to be concerned with. As previously recommend, if you want to slow down the extraction of the spent casing, you can definitely try a heavier buffer and buffer spring.
S/F Joe |