AR Sponsor
Posted: 1/5/2007 2:57:09 AM EDT
I am having feeding issues with my ar. Actually, it's my dads, but i got elected to be his gun cleaner/smith quite a few years ago.  Last time at the range the rifle quit feeding. Here is a pic of what is happening. Picture I disassembled it and found that the pin that holds the extractor in was broken. I replaced it, but this did not fix the problem. I have also tried another pin just for the hell of it. Same thing. While i was trying to figure out what else to do, i noticed that there was an unusual amount of wear on one side of the bolt. It seems to be impacting something because there was a large burr (area circled) I used a stone to remove this burr, and tried again. Picture I noticed (by chance) that the bolt seems to be machined improperly. Unless the cuts on the bolt are not supposed to be "square" Picture If anyone knows what else i can try, please let me know. Otherwise, i am just going to buy a new bolt carrier. Thanks in advance for any help Tony |
|
Tony, there are couple of things that we will need to know to help you trouble shoot the rifle. 1. Will the B/C pass a 45* free drop test? This is done by shot gunning the upper open off the lower, angling the muzzle downwards (45*), sticking your finger in the back of the carrier and pulling it back until it limits out on the charging handle, then letting go of it to see if the B/C will slide back down on it's own. The reason for this is to confirm that the key section of the carrier is not binding in the upper receiver track, and that the Forward assist pawn is full retracted and not binding up on the carrier. 2. With the bolt almost locked up, have you been using a chamber brush to correctly clean the chamber? Also, in regards to cleaning and lubing the rifle, there are a few posts tacked over in the Maintenance & Cleaning forum that you may want to take a look at. 3. Have you performed a short stroke test on the rifle? This is done by loading only a single round into a mag, loading and charging from the mag, and firing the round, with hopefully the end result being the bolt locked back on the bolt catch. If the rifle fails this test, then items like a loose key, hammer bind, and even ammo selection come into play (depending on the rifle brand). Now regarding the carrier ramp, granted it’s not one of the more perfect units I have seen, but I have seen worse and with the bolt actually making it way to the barrel extension, the ramp is serving it’s purpose. The fact that the FP pin snapped (really need a round count on the old unit), it could be that the hammer is catching the FP on the forward stroke, and a hammer mod would be better served than replacing the carrier. To test for the FP collar being caught by the hammer, you just need to pull back on the charging handle with the rifle unloaded, and then ride the handle back down slowly. If the B/C will not slide down on it’s own (rifle unloaded with no ammo being used), then you have a binding issue that needs to be resolved. Simply, we will need the configuration/brand of the rifle, the round count through the rifle, the ammo brand/type being fired, and conformation that you have fully cleaned the rifle, including checking for blown primers/debris in the action, before you retested to double check the functioning of the rifle. |
|
Drop Test- The B/C will slide smoothly all the way down and lock in. Cleaning- It has been meticulously cleaned every time it has been fired. I am pretty anal about that, so no worries. Short Stroke Test- I haven't dont a short stroke test. However, it has always locked back at the end of a magazine. I can't try this because the rifle not chambering a round from the mag(fully loaded or with just one round) is my problem. I have tried numerous other mags just to make sure that isn't the issue. Config/Maker- A2 Colt Sporter/Match HBAR Round Count- 500 give or take 50 Ammo- Have shot Winchester White Box, Black Hills, and Wolf. The Wolf ammo was the first 200 rounds fired. Since then Winchester and Black Hills I have tried different types of ammo to make sure i just didn't get a lot of ammo that wouldn't fit. It won't chamber a round with Hornaday TAP or surplus ammo either. There are no blown primers or debris in the action. I just swallowed my pride and double checked anyways. Thank you for your help and for being descriptive when explaining the tests you wanted me to do. Otherwise i would have had to ask what the Drop Test was. |
|
With the carrier passing the 45* test, we now know that the gas tube is not misaligned as well. Since you started out with Wolf ammo, lets just do a good chamber brush cleaning, followed by a 30 cal mop soaked in CLP on a few cleaning rods spun in and out of the chamber with a drill (just the mop, not the chamber brush). Could be that the last step cut of the chamber is just fouled out, and your current cleaning method is not getting this last of the fouling out of the chamber. |
AR Sponsor