AR Sponsor
Posted: 10/19/2013 2:58:07 PM EDT
|
First time build so forgive my lack of experience.....so I get the BCG all lubed up and insert it along with the charging handle and what I'm finding is the bolt isn't perfectly aligned with the grooves in the breach of the barrel so the bolt won't go in and seal the breach. I realize the bolt should sort slide in-and-out of the bcg to adjust vary the location of the bolt presumably so it seals the breach. Although it moves freely when out of the upper, when you place it in the upper, the bolt has to be extender out fully otherwise the cam pin conflicts with the opening to the upper where the BCG slides in. When the bolt sits against the breach of the barrel, the grooves should be twisted maybe 15 degrees so they mesh but I don't want to push too hard for fear of damaging something.
Here's a pic of the breach of the barrel from the underside of the upper, and then the bcg inserted: http://www.perfectswitch.com/images/barrel.jpg http://www.perfectswitch.com/images/barrel2.jpg http://www.perfectswitch.com/images/barrel3.jpg |
|
The bolt does not seal the breech. The brass casing of the ammunition round expands to make a seal.
The bolt carrier group is not going to fully close, unless the bolt is in the fully extended position when the bolt is closed. When the bolt is fully extended it will fit between the locking lugs machined onto the barrel extension. The cam pin is designed to rotate the bolt and lock the bolt to the barrel extension AFTER the lugs on the bolt pass the lugs on the barrel extension. The bolt will rotate to it's fully retracted position when it's locked to the barrel. |
|
Quoted:
First time build so forgive my lack of experience.....so I get the BCG all lubed up and insert it along with the charging handle and what I'm finding is the bolt isn't perfectly aligned with the grooves in the breach of the barrel so the bolt won't go in and seal the breach. I realize the bolt should sort slide in-and-out of the bcg to adjust vary the location of the bolt presumably so it seals the breach. Although it moves freely when out of the upper, when you place it in the upper, the bolt has to be extender out fully otherwise the cam pin conflicts with the opening to the upper where the BCG slides in. When the bolt sits against the breach of the barrel, the grooves should be twisted maybe 15 degrees so they mesh but I don't want to push too hard for fear of damaging something. Here's a pic of the breach of the barrel from the underside of the upper, and then the bcg inserted: http://www.perfectswitch.com/images/barrel.jpg http://www.perfectswitch.com/images/barrel2.jpg http://www.perfectswitch.com/images/barrel3.jpg That barrel assembly index pin and/or barrel extension is out of time... HORRIBLY!!! Either that, or your upper receiver index pin cut out slot is cut at an 11 o'clock cant and is throwing things way off. Damn, that is the worst fu*king alignment I've ever seen. Who is the manufacturer of the upper receiver? Who is the manufacturer of the barrel assembly? I bet I can guess who the manufacturer of the barrel assembly is... |
|
Quoted:
Thanks guys.....got it figured out. Barrel slipped out of its groove so I got it re-installed and all is right in the world. Good. I'm curious though, how did the index pin slip out of it's groove? It would almost have to be sheared off to slip out of the receiver cut out. Post a pic of how it sits now from the same angles you did previously please. Just checking on you, not critiquing you bro... |
AR Sponsor