Hi, i would like to know if the Gas Block on the M27 is vented like the more recent Models of the HK416 assault rifle or if it is closed on front. I read about the problems the IAR has when operating the gun with the KAC suppressor and was told, the reason lays in the gas block being not "self regulating" like the newer ones are. Newer 416 Rifles would blow excessive gas out of the front hole, so eliminating the need of a adjustable gas block.
So back in the day, the first 10.4" guns did not have the bleed-off port directly in front of the piston on the gas block. Somewhere around "BA" date code (2010) maybe earlier they started putting the port in the front of the gas block of the 10.4" guns. The 14.5's have always had them. The MR556's and MR223's have always had them. The 20" guns have them. I'm 99% sure the M27 16" barreled guns have them as well.
The bleed-off port can only do so much. Like a traditional DI gun, gas port size and location matters. Throw in a can and that adds to the issues. That bleed-off can only expel so much pressure. I'm fairly certain that while all current non- AGB (adjustible gas block) guns have the port, they are all sized differently.
Have to ask @Arctic1 if the 416N's had a bleed-off port in theirs with the early AGB design.
The HK416N, first fielded in 2008, had the bleed-off port.