"inherited" an AR build: barrel/HG/ out of plumb?

[Buckskinner]

I just posted this at arfcom just in case.



My first AR: Mega flattop upper 16"HBAR and SNS lower. The guy I bought it from was a bit more ingnorant than me, but not much. He said his friend the "gun nut" put it together, with a custom bolt and such.
It has a free floating hand guard ("Olympic Arms" on it), and I noticed that the front sight was not plumb. Not knowing what else to do, I wrenched on it by hand, and the barrel rotated slightly under max pressure. Is that normal? Problem is, now the alignment of the front sight, handguard rails, and reciever rails are worse. What problems do I have and how do I fix them myself?

Next problem: when dry firing, I "ease to reset" the trigger, and it seems to drop the hammer. When broken apart and holding the hammer from hitting the lower, this exercise doesnt' always drop the hammer, but its very sensitive.

 

[taliv]

there is a safety/function check with the ARs where you squeeze the trigger and hold it back, then cycle the bolt, while still holding the trigger. then when you release the trigger, you should hear a "click", which would be the hammer being captured by the sear (I believe), NOT the hammer dropping.

If the hammer is going forward when you release the trigger, I'd say that's unsafe and you should take it to a gunsmith.

In fact, given the used condition and possible association with arfcom gun nuts, i'd replace the trigger group entirely on the chance it's been modified by someone who doesn't understand just how illegal machine guns are.

and no, movement of the barrel/rails/receiver is NOT normal. Depending on the model, it's unlikely to move too far, as the gas tube will prevent most of them from spinning more than a few mm, but you want to get that fixed by someone who knows how to install rails, etc.

It would make me extremely skeptical about how the gas block was installed too.

 

[Coronach]

Yeah, this thing needs to go to a gunsmith, or at least someone who knows how to wrench an AR.

Neither of the two conditions you describe are normal, and either one of them could end up being very bad. Chances are the fixes will be fairly simple (properly re-installing the barrel, replacement of the FCG). If you have minimal mechanical skills you can get a replacement FCG pretty cheap and do that part yourself. The barrel/handguard, though...that's probably not a DIY for you (unless you want to invest time, effort and money for tools).

Mike

 

[jerkface11]

Someone put Oly parts on a Mega upper? That's like putting an audiovox head unit in a mercedes.