I'm looking to build a Service Rifle AR15 for CMP EIC, and there are certain rules that must be adhered to. The big ones are:
-5.56/.223
-Stoner gas impingement or piston, NO adjustable gas block
-20" barrel max, no portion of the barrel may exceed 0.75" forward of the gas block
-No muzzle brake or compensator. Flash suppressor is allowed, but not required
-To my understanding, there is NO weight limit
There are several other rules and largely don't matter for this post, but for reference, a 4.5 power optic isn't required, but is allowed. The trigger must be a minimum of 4.5 pounds, and can either be a single or two stage. So there is some leeway allowed in the rifle. While I certainly don't want to cheat, if a rule is not explicitly mentioned, I'd assume there is no limitation. But, assuming can be dangerous.
About the only thing I can come up with is a low mass BCG, but I worry about running one without an adjustable gas block. Instead of an adjustable gas block, are there adjustable buffer/springs that can somewhat do the same thing? JP Enterprise silent capture? I know there are adjustable gas tubes, but, I feel that would be pushing it. Is it possible to have a fixed gas block with a smaller gas port, or one that you drill out yourself? That would take a lot of time to tune, but, technically be legal?
My only other thoughts are, I know the flash suppressor isn't a muzzle brake. But does it offer ANY kind of recoil reduction? The rifle is supposed to "exhibit a general overall external appearance to the M-16"; which is how I think the "internal" modifications listed above will probably be acceptable.
Hopefully I'm not just chasing impossible ideas here. If nothing I've mentioned above will work, I'll probably buy a service rifle instead of build. Thanks for any input.
-5.56/.223
-Stoner gas impingement or piston, NO adjustable gas block
-20" barrel max, no portion of the barrel may exceed 0.75" forward of the gas block
-No muzzle brake or compensator. Flash suppressor is allowed, but not required
-To my understanding, there is NO weight limit
There are several other rules and largely don't matter for this post, but for reference, a 4.5 power optic isn't required, but is allowed. The trigger must be a minimum of 4.5 pounds, and can either be a single or two stage. So there is some leeway allowed in the rifle. While I certainly don't want to cheat, if a rule is not explicitly mentioned, I'd assume there is no limitation. But, assuming can be dangerous.
About the only thing I can come up with is a low mass BCG, but I worry about running one without an adjustable gas block. Instead of an adjustable gas block, are there adjustable buffer/springs that can somewhat do the same thing? JP Enterprise silent capture? I know there are adjustable gas tubes, but, I feel that would be pushing it. Is it possible to have a fixed gas block with a smaller gas port, or one that you drill out yourself? That would take a lot of time to tune, but, technically be legal?
My only other thoughts are, I know the flash suppressor isn't a muzzle brake. But does it offer ANY kind of recoil reduction? The rifle is supposed to "exhibit a general overall external appearance to the M-16"; which is how I think the "internal" modifications listed above will probably be acceptable.
Hopefully I'm not just chasing impossible ideas here. If nothing I've mentioned above will work, I'll probably buy a service rifle instead of build. Thanks for any input.