AR Sponsor
Posted: 8/10/2010 11:41:26 AM EDT
|
I picked up a brand new upper from a manufacturer I know has had several problems with their rifles (MMC / Moore Machine Company). The rifles had a lot of feed issues The bullets would hit the upper receiver below the feed ramps and cause stoppages (IF you could even get the rifle to load a round). I believe their lowers were out of spec and that the uppers were probably ok. I picked up the upper for $200 complete w/ bcg. After putting it on a Spike's lower and putting 20 rounds through it I got a failure to extract followed by a few more before making it through the 30 round mag.
I started another mag but the failure to extract problem just kept happening. The barrel is NOT chrome lined and is supposed to be chambered for 5.56mm Here is what the casings look like after failure. 
There are rings on every shell casing. I have never really noticed this after firing any other ammo through my other AR's. You can also see the lip of the casing has almost been pulled off. I knew there was a chance of issues with this upper, but for $200 I don't feel bad. I can salvage some usable parts from this if I can't figure out what's wrong and fix it. UPDATE Well I found a solution. I sold the upper! My cheap AR project has now gone full retard with a change to Expensive AR project. I have already submitted my paperwork for my first SBR. DAMN YOU EE! I replaced the upper with a Spike's Tactical 10.5 LE upper. PROBLEM SOLVED! 
|
| Good call, it looks like a poorly reamed/polished chamber. Clean any oil or grease from the chamber (just in case) and then polish the chamber and fire for effect. That is IF the chamber is not chromed, if the chamber IS chromed get it to a good gunsmith to see if he can clean up the chamber finish with the proper finish reamer for a chromed chamber. OR just get another barrel. Let us know the outcome....<><....:) |
|
Quoted:
How much oil is in the chamber? It looks like a case resized for reloading that has too much resizing lube on it. Most likely it needs reamed or replaced. There was some heavy oil in the upper. Nothing unlike I have seen in some new guns. However those other guns were quality and they didn't have issues. I cleaned it completely and will be giving it another shot soon. It is not a chrome lined barrel. Worst case I had planned on replacing the barrel. I'd like to get this one working cheap since I will have about $430 dollars total in this AR. |
|
I've been doing some more searching and I stumbled across this.
http://www.brownells.com/.aspx/pid=651/Product/FLEX_HONE_RIFLE_POLISHING_SYSTEM 
Anybody ever tried this? |
|
Yes. That is a hone. About $35-$50 each. It usually takes a rough hone, then a smooth hone to polish the chamber properly. It also takes a specific, special oil which forms a slurry that does most of the cutting. The wrong oil ruins the hone quickly. I don't see anything for the neck. What will you do there?
|
|
Quoted:
Yes. That is a hone. About $35-$50 each. It usually takes a rough hone, then a smooth hone to polish the chamber properly. It also takes a specific, special oil which forms a slurry that does most of the cutting. The wrong oil ruins the hone quickly. I don't see anything for the neck. What will you do there? Pray, make a wish, or something of that nature. |
|
Quoted:
I picked up the upper for $200 complete w/ bcg
This could be part* of the problem. * Meaning all of the problem of course. I knew it was a gamble but I also knew what the problems it was having were. Don't worry I won't be kicking down doors with it. Tell me you wouldn't build an AR for less than $500 as a range rifle? |
|
Quoted: Quoted: How much oil is in the chamber? It looks like a case resized for reloading that has too much resizing lube on it. Most likely it needs reamed or replaced. There was some heavy oil in the upper. Nothing unlike I have seen in some new guns. However those other guns were quality and they didn't have issues. I cleaned it completely and will be giving it another shot soon. It is not a chrome lined barrel. Worst case I had planned on replacing the barrel. I'd like to get this one working cheap since I will have about $430 dollars total in this AR. That's what I would try first. Always try the cheapest solution first. Keep us updated. |
|
To me it appears the chamber has scoring left by the finish reamer.
This occurs if the reamer was not properly cleaned after each pass and chips adhereing to the reamer cut rings into the chamber walls or the reamer was removed from the chamber while it was still turning. The extractor is ripping the case head when it tries to pull the case, which has expended into the grooves left in the chamber, from the chamber. Sometimes a chamber can be re-finish reamed to remove light scoring but if the rings are deeply cut into the chamber, the barrel is effectively trashed and needs to be replaced. |
|
That looks pretty rough indeed! Normally, I would fit patch with flitz on an old chamber brush and spin it at low speed with a drill to polish it up a bit, but I don't know if it will take THAT much off. At this point, however, I don't think you'll hurt anything.
And I agree with an earlier poster. If you have to re-ream the chamber, you'll have to have the barrel extension brought in to maintain the headspace, and then you may have issues with the front sight being exactly right, etc. For the money and trouble, I'd probably opt for a known high quality barrel source and just re-barrel it. Given what you have in the upper right now, you'd still be money ahead. Saleen |
| I had a barrel with what we thought was a chamber problem and the maker told me to polish it with Flitz around a tight fitting mop but don't go so deep as to get into the rifling. It seems to gotten the chamber smooth as silk but it turned out to be something else. Flitz around a mop has also been used in RR .458S chambers that have had problems. So... |
| a GOOD gunsmith clearing up the chamber using a FINISH reamer will have no effect on the way the barrel extention is fitted and should add NOTHING to the headspace issue. If he does he is not a GOOD gunsmith, he is not even a gunsmith, but rather a backyard hack. The Flitz would not hurt and might help, just go slow and straight, don't put undue pressure or time on any one side of the chamber. Heck, I'd be willing to buy the barrel from you (cheaply of course) just to try the Flitz...<><....:) |
| Had the same problem years ago with an upper i bought cheap at a gun show. It wasnt chrome lined so i took a chamber brush and wraped it with steel wool put it on a cleaning rod and stuck it in the cordless drill and let her rip, never had another problem with it , just dont go crazy with it. |
|
If that was the replacement you should have learned your lesson now. You get what you pay for as the saying goes. This looks like a rough chamber before the company that profiles the rifle send it off to be plated. Someone forgot a step.
You asked about would I buy a rifle that cost less than $500. Well seeing that my time is worth something and I have to fix the rifle after the "manufacturer" ....uh "finished it" I would say that the rifle just increased in price. To answer your question on what to do. I would get rid of the WHOLE thing. If the barrel is that bad off and the upper cost only that much for you I am guessing the remaining parts aren't much better. |
AR Sponsor