308 AR build help please

[Crazydoc68]

take a pic of yours Doc for him to compare

Just had the same thought!

 

[Crazydoc68]

Here's the feed ramps/barrel extension. I need to dremel them but were they meet is smooth so I'm sure this is the cause of the problem.

thanks for the help everyone!

Return the upper reciever and let them know the issue....how that made it past QA/QC is beyond me......that's crazy

 

[FLO]

I didn't think of returning it because it's a Mega barrel and Aero upper so I have no idea if a Aero barrel extension matches it. I guess I can send them a pic and get their opinion.

thanks guys!

 

[Crazydoc68]

Is it a 308 upper? Have to ask.

 

[Marquezj16]

This is what mine looks like.

 

[bigbulls]

Looks to me the problem lies in the barrel extension and not the upper. Looking at how the cuts in the upper line up equally with the pin block equally it appears to me that the barrel extension is rotated past center..... clockwise from our perspective. The locking lug on the right is considerably wider than the locking lug on the left of the feed ramps. Your barrel extension feed ramps are most definitely cut off center.

DEFINITELY DO NOT TAKE A DREMEL TO IT!

Does the problem happen when a round feeds from both sides of the magazine or does it only happen on one side?

 

[FLO]

Looks to me the problem lies in the barrel extension and not the upper. Looking at how the cuts in the upper line up equally with the pin block equally it appears to me that the barrel extension is rotated past center..... clockwise from our perspective. The locking lug on the right is considerably wider than the locking lug on the left of the feed ramps. Your barrel extension feed ramps are most definitely cut off center.

DEFINITELY DO NOT TAKE A DREMEL TO IT!

Does the problem happen when a round feeds from both sides of the magazine or does it only happen on one side?

View attachment 31101

Yes I put 2 rounds in a mag and the same thing happened. I tested 2-rounds multiple times.

 

[FLO]

Well, I sent a bunch of emails and pics to all parties involved. Hopefully I get some feedback tomorrow. This sucks!!!

thanks everyone for the help. I'll keep posting news as I get it. I'm in a holding pattern for now.

 

[Crazydoc68]

Well, I sent a bunch of emails and pics to all parties involved. Hopefully I get some feedback tomorrow. This sucks!!!

thanks everyone for the help. I'll keep posting news as I get it. I'm in a holding pattern for now.

Hope Mega makes good on a new barrel. Keep us posted....

 

[FLO]

One thing I haven't done is test metal magazines. I ordered a few ASC mags so we'll see how they do. A guy from another forum swears the problem is mag related. I guess I'll find out soon enough. Either way, i think those ramps are not right. More to come.

thanks!

 

[Crazydoc68]

I have 4 ASC mags. They allow you to seat bullets longer if you handloading. I haven't had any issues with mine.

Doc

 

[Marquezj16]

I only have Pmags, both 20 rd and 10 rd mags. They have functioned 100%.

 

[Telum Pisces]

Here's my .308! Notice the smooth alignment and transition in the feed ramps etc... Your's is way out of wack!

 

[Crazydoc68]

Here's my .308! Notice the smooth alignment and transition in the feed ramps etc... Your's is way out of wack!

What upper do you have?

 

[Telum Pisces]

What upper do you have?

DPMS Upper

It's a full DPMS rifle. Not a build. LR-308

 

[Crazydoc68]

Nice looking feed ramps!

 

[Telum Pisces]

Nice looking feed ramps!

This thing eats just about anything. I've only had one or two russian MFS steel cased rounds hang up in this thing. Pmags, steel mags, doesn't matter.

Building a .308 is a whole different animal compared to slapping together a normal AR in 5.56 etc... In the .308 world things are proprietary and things don't always mix and match between makers etc... That's why I just decided to go with a complete rifle instead of a build.

 

[Crazydoc68]

Kinda why I just went with the same. I just ordered a complete upper from PSA along with their lower. I wish and hope one day that things are made interchangeable.

 

[FLO]

Update! I got my backup bcg in the mail today and swapped it out and was able to chamber several rounds from each of my 4 magpul mags witihout any problems. When I compared the 2 bcg's i noticed the ejector on the failing bolt was out just a tad more than the new one. I removed the pin and spring and replaced them with new ones from my bolt spare parts kit. The only thing I noticed is the original retainer pin is very thin and slightly bent. I might have caused this when I checked headspace last week. Either way, now the original bcg cycles without any hangups after several rounds from each of the mags. Now I can move on to actual test firing and adjusting the gas block!

thanks everyone

 

[bigbulls]

That's good news but I would still get that barrel replaced before you start shooting. That barrel is not machined properly. Get it fixed now before it gives you a headache later.