NEED help with my AR build!!! - Page 1

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[ARCHIVED THREAD] - NEED help with my AR build!!!

Posted: 9/1/2015 8:47:58 PM EDT

I completed my build and everything fits fine (so I think) but it is impossible for me to rack it. I littertly have to use both of my hands and a vary fair amount of strength just to rack it. Is there anyone who has some advise or can help me out with my problem? Thanks in advance to whoever reply with any kind of suggestion.

Posted: 9/1/2015 8:54:49 PM EDT

[#1]

Parts list pls

Posted: 9/1/2015 9:00:58 PM EDT

[#2]

separate the upper and lower.

using the charging handle, try to move the bcg out. and then push it back in. do you encounter resistance anytime during these motions?

take the bcg out and try working the charging handle by itself, any resistance there?

do you have the bcg lubed and properly assembled? didnt forget the cam pin or something?

also take a look at the lugs on the bcg and the receiver extension (inside the upper). anything look unusual?

the lower could also be the issue but try to narrow it down first

Posted: 9/1/2015 9:16:07 PM EDT

[#3]

Standard GI charging handle and BCG in a mega arms upper

Posted: 9/1/2015 9:19:16 PM EDT

[#4]

K give me a few mins i'll go over everything you just said thoroughly

Posted: 9/1/2015 9:20:11 PM EDT

[#5]

Upper receiver or charging handle is out of spec probably.

I had an out of spec charging handle once on a .308 I built. It was so rough, that the bolt would hold open with out the bolt catch.

I applied 600 grit lapping compound and on the charging handle and inside the upper receiver. I kept riding the charging handle back and forth until it started to free up. After about 10 minutes, it was as slick and smooth as butter.

Posted: 9/1/2015 9:38:06 PM EDT

[#6]

I had one lower and CH that when assembled, the top of the lower receiver, over the extension threads, pressed so hard up on the bottom of the CH that it was very hard to operate. Another CH and the problem went away. Check first that the CH is not dragging on the lower above the receiver extension threads.

I also had a receiver end plate that was a bit too high and completely blocked the CH from being pulled at all. That was an easy fix with a pillar file and some Aluma-Hide II.

Posted: 9/1/2015 11:42:01 PM EDT

[#7]

I think it has something to do with the bolt and barrel because thats the hard part but as soon as I get it past that part its perfectly normal. I tried to lube it up even more but still the same. Idk what else to do. If I can't figure it out myself in the next day or so i'm gonna just bring it to a gun smith

Posted: 9/1/2015 11:46:23 PM EDT

[#8]

Quote History

Quoted:
Parts list pls

View Quote

Posted: 9/2/2015 12:03:41 AM EDT

[#9]

Remove the extractor from your bolt and try it. Definitely separate the upper and lower to narrow it down. Look for any shiny spots inside the reciever . Take pics

Posted: 9/2/2015 12:08:05 AM EDT

[#10]

Quote History

Quoted:
I think it has something to do with the bolt and barrel because thats the hard part but as soon as I get it past that part its perfectly normal. I tried to lube it up even more but still the same. Idk what else to do. If I can't figure it out myself in the next day or so i'm gonna just bring it to a gun smith

View Quote

After separating the upper from the lower, it is still difficult to pull the BCG out with the charging handle? What about when you install the BCG back into the upper, does it offer any resistance?

A parts list and possible pics would be helpful.

Posted: 9/2/2015 1:08:28 AM EDT

[#11]

Gas tube/key?

Posted: 9/2/2015 1:55:55 AM EDT

[#12]

Did you take the firing pin out of the carrier to "Be Safe?"

if so, put it back in.

Posted: 9/2/2015 2:02:01 AM EDT

[#13]

We really need pics to help, if we had pics it would save you some money by going to the gunsmith.

Posted: 9/2/2015 2:04:50 AM EDT

[#14]

Quote History

Quoted:
Did you take the firing pin out of the carrier to "Be Safe?"

if so, put it back in.

View Quote

"This is my safety sir"

Posted: 9/2/2015 3:04:44 AM EDT

[#15]

Quote History

Quoted:
Did you take the firing pin out of the carrier to "Be Safe?"

if so, put it back in.

View Quote

First thing I thought of. If you took out the firing pin, put it back in and consider yourself extremely lucky.

Posted: 9/2/2015 9:45:00 AM EDT

[#16]

How bout a list of components. "Standard GI bcg" gives us no info. The ch I can understand being "standard" no name. What brand bcg is it. Radical? I've heard their components are shit. Daniel Defense? Color me surprised. Cmon OP what parts.

Posted: 9/2/2015 4:20:57 PM EDT

[#17]

With some uppers the cam pin drags within it and makes it difficult to turn. This is noted by flipping the upper upside down and looking for wear in the top of teh upper. Most good manufacturers clearance for this, but sometimes not. The cam pin not being able to rotate would certainly cause your symptoms.

I will say I had a very similr problem, and it was related to the cam pin. However, the problem wasn't clearance, but rather in the coarse of machining the pin a fine piece of steel was left that came loose when I first cycled the action. After having to mortar it to get it out of battery I found that, still attached right at the top of the shaft of the cam pin. Snapped it off, no more problems. I'm sure this was incredibly rare, but it still caused the same problem by not allowing the pin to rlide and rotate through its cycle.

Posted: 9/2/2015 9:39:30 PM EDT

[#18]

No I didn't take the firing pin out. It's still in there. As for pics I will try to get take a few as soon as I can. As for taking the CH and BCG out while it's taken apart there is no problem taking it out or putting it back in. Pics are coming as soon as I can get to it. Thank you everyone who has tried to help so far with there input.

Posted: 9/2/2015 9:45:42 PM EDT

[#19]

As for the BCG there is literly no engravings on it whats soever. I got it at a gun show for 15 bucks because I bought a Mega arms upper from them and they threw in the CH as well

Posted: 9/2/2015 10:22:10 PM EDT

[#20]

Check around your buffer tube and detent. Maybe even remove the detent and see if it's catching the rear of the Bcg, if that detent is too high it's an easy fix

Posted: 9/2/2015 10:49:02 PM EDT

[#21]

I had a build do that once... it was the cam pin. I remover a VERY SMALL amount of metal from the rear outer corner and the problem was solved. With the BCG together facing as if it is in the rifle, it was the left rear corner that caused the jamming issue.

Posted: 9/2/2015 10:56:37 PM EDT

[#22]

Quote History

Quoted:
I think it has something to do with the bolt and barrel because thats the hard part but as soon as I get it past that part its perfectly normal. I tried to lube it up even more but still the same. Idk what else to do. If I can't figure it out myself in the next day or so i'm gonna just bring it to a gun smith

View Quote

I was recently shopping for a Ruger AR556 and I was about to buy one when I discovered it was doing the same thing. Actually, this one was a little different because it would lock up when dry fired. Once I got it racked, which took some pulling, and jiggling, and even more pulling, I could rack it over and over with no problem. The store I was at sells complete bolt carrier groups, and the guy behind the counter opened and installed one of them, and it worked perfectly.

My own theory is that the bolt was camming over too far. The cam pin suggestion posted already sounds like a good one. It might have a sharp edge that needs knocked off.

Posted: 9/2/2015 11:36:26 PM EDT

[#23]

Quote History

Quoted:

As for the BCG there is literly no engravings on it whats soever. I got it at a gun show for 15 bucks because I bought a Mega arms upper from them and they threw in the CH as well

View Quote

That might be your answer. Someone charged you for an out of spec BCG that they had no intention of returning to the OEM.

Posted: 9/2/2015 11:52:56 PM EDT

[#24]

The barrel extension probably has some burrs on the inside, binding the bolt when it locks. It should resolve itself through normal use.

Posted: 9/3/2015 12:55:12 AM EDT

[#25]

Quote History

Quoted:
As for the BCG there is literly no engravings on it whats soever. I got it at a gun show for 15 bucks because I bought a Mega arms upper from them and they threw in the CH as well

View Quote

Do you remember the actual cost of the BCG or did he only charge you $15 because of you bought the upper? I'd be a little weary of a $15 dollar BCG.

Posted: 9/3/2015 3:12:52 AM EDT

[#26]

Do you have any markings at all on the carrier or bolt? If USGI, it should say MPI or something. Sounds like you have El cheapo, out of spec parts.

Posted: 9/5/2015 3:07:22 PM EDT

[#27]

Quote History

Quoted:
As for the BCG there is literly no engravings on it whats soever. I got it at a gun show for 15 bucks because I bought a Mega arms upper from them and they threw in the CH as well

View Quote

Pics of BCG and upper. There will be some witness marks of the interference, I am guessing. Cam pin is a likely culprit on the $15 bargain. Try one of your other known-good BCGs and see how it works

[ARCHIVED THREAD] - NEED help with my AR build!!!

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