Posted: 8/24/2004 7:44:17 AM EDT
This weekend I was looking at the inside of the barrel assembly of my .223 carbine (Armalite) and I notice that there are eight (8) ammo feeding ramps cut at the rear of the chamber. The five (5) of these ramps toward the upper portion of the chamber/barrel are uniformly cut in a four-sided basically square pattern BUT the 3 at the bottom of the chamber/barrel are cut different from the top 5 in that they are NOT four-sided but have a multi type five (5) surface diamond type cut.
Is the above normal or is there a flaw in the cutting of these feeding ramps ????
P.S. I have not shot the gun yet, since I have not put a scope on it, so I don't know if the ammo will feed correctly.
The only feeding ramps in an AR15/M16 rifle are the two rounded, angled slots on the bottom. Everything else are slots for the locking lugs on the bolt to go through as the bolt closes.
And to be frank, from your description, I don't have the slightest idea what you're talking about. Maybe it'll make more sense to me after I'm fully awake
wpshooter, what you were calling "feed ramps" are actually the locking lugs of the barrel extension that act in unison with the locking lugs of the bolt.
In the above picture, the actual feed ramps are the two dished out or milled out reliefs in the bottom of the picture. There are 2 of these reliefs because the cartridges feed from the magazine in an alternating "left, right" fashion thanks to the double stack magazine.
The material removed from the barrel extension(the part that contains the locking lugs in the receiver) to create the feed ramps winds up modifying 3 of the locking lugs.
Yes, the above is normal. The majority of manufacturers have feed ramps that look like the example on the left while a few mill "M4" type feed ramps into their barrel extensions and so much material is removed that a slight portion of material extending into the upper receiver also needs to be removed.