AR Sponsor
Posted: 3/12/2004 8:29:23 AM EDT
| I built a lower some time ago and just recently had a chance to test it. It is a RRA lower and parts kit with a Tactical stock. I had a few problems putting it together but got it worked out I thought. Well I put the lower on my factory built upper and had some problems. It would fire one round and then seemingly not allow the round to cycle into the chamber. When I pulled the bolt back to cycle the round out it would then fire 1 round and repeat the problem. At that point I put my other factory built lower on the upper and it functioned flawlessly. So I figure its the lower. Any ideas what the problem could be? |
|
There are 3 areas I would check first: Swap the stock/tube assy along with buffer and spring from the "good" lower to the RR and fire for function. This will point up a bad stock assy and/or buffer. Second, remove the bolt hold open (along with spring and plunger so they are not lost). Go fire for function. Of course, no hold open with the stop removed. Some of the bolt stops drag on the bolt enough to cause short stroking. If gun functions with stop removed, you probably need to grind the high corner of the stop down till it quits dragging on the bolt. Third, the hammer tail could be too long, causing excess pressure on bottom of bolt. Look for shiny area on disconnector where the hammer tail approaches it. If shiney, trim the tail back a mm or 2. Also, some of the firecontrol parts can be out of spec because of tolerance stacking. As you manually cock the hammer, the disconnector should pop out of the way just before the middle hammer hook touches it. If there is a lot of pressure before the disco pops, try another hammer or disco. |
|
Just to add (on a unloaded rifle), Pull back on the charging handle, then slowly ride it forward. Do this with the trigger at rest, and the trigger held back. Does the carrier (firing pin) bind up on the hammer and stop the carrier from fully closing (around half way forward)? |
AR Sponsor