AR Sponsor
Posted: 12/12/2004 5:14:46 AM EDT
| I have several AR-15's and would like to build a new 24" varmint based on the dpms Hi-rider upper. This upper has no forward assist, dust cover or ejection bufer to direct the spent cases. I collect my brass for reloading and like the fact that with all my bushmaster uppers it is in the same general area. Anyone have one of these and where does it put the brass? |
|
Dead blow effect of the buffer, and the strenght of the ejector spring will determine the ejection path. If you pack all the weights in the buffer so they don't move, then the spent cases will be thrown forward (not dead blwo effect). If you clip the ejector spring a few coils, then the case will not be pivioted off the bolt at dead blow effect of the standard buffer, and will be thrown off on the forward stroke (forward). Also, you could install an adustable gas tube. With this, you can have the rifle just dribble the spent cases out of the rifle (action cycle slowed way down). |
|
I have one of these uppers on an NRA match rifle. The ejection path is to 3:30. The case comes out of the bolt and rotates 180 degrees, hitting the outside of the receiver where the deflector lives on a plain upper. The cases get little dents that can be mitigated by sticking the fuzzy side of a velcro strip on the receiver. Some folks use a layer of black silicone - whatever floats your boat, they both work. Buffering the impact point also helps reduce the distance the brass will fly. I definitely would try one the pad methods before I start trimming the ejector spring, and even then, it's hard to recommend this step except for guns that absolutely will never be needed for defense. If a target or hunting gun dies, it's no big deal, so many highpower shooters do this. This receiver is much stiffer than run of the mill parts - without measuring the gun, my guess is that the side walls around the bolt carrier are slightly more than twice as thick as an A2 upper, then the geometry of the raised sight rail adds additional stiffeness by increasing the area moment of inertia of the cross section; i.e., this added height increases the beam stiffness. I also have an adjustable gas block, but I have had limited success - it doesn't regulate the gas linearly and tends to either give too much or too little. I may make a tapered needle valve for it this winter to see if that helps. |
| I have a dpms low pro receiver on a nra match rifle. I clipped the ejector spring alittle at a time to get the brass to land out at my 2o'clock at three feet. The dpms seem to be different enough in the port design than a std A4 receiver that if you clip off the number of coils that works well with the A4 - the dpms will stove pipe the brass in the port. I had a A4 upper that would dump all the brass right at 1 o'clock at about two feet away all in one pile. I haven't been able to get my dpms to do that yet, the brass bounces off the port opening and with a mild ejector spring they will stove pipe. I also have opened up the port(mostly to get my fat fingers in to single load) and flared the front of the port to deflect any slow ejection - that helps the brass to clear better. I would think a std ejector spring would kick the brass out at 4 or 5 o'clock like any unmodified 20" barrel/gas system. |
AR Sponsor