barrel extension question

[rcromwell92]

I have been having feeding and ejecting issues on my Ar308 rifle all parts were originally Daytona tactical. So, I purchased and installed an Odins works Adjustable gas block, new bolt and switched from an 18" daytona tactical barrel with a mid length gas system to a primary arms 20" barrel with rifle length gas system. I am still having the issue. My upper doesnt have the M4 feed ramps nor does the barrel extension. So, I am thinking about purchasing this barrel extension https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrel-hardware/barrel-extension-parts/ar-308-ar-style-308-extension-prod40776.aspx that has feed ramsand swapping it out. However, I cant find any info on how to change one out. Can someone point me in the right direction on how or where to get this done in Commifornia. Also, is it going to be an issue if the barrel has them but the upper does not? Any and all help is greatly appreciated. Thank you in advance

 

https://www.brownells.com/rifle-parts/barrel-parts/rifle-barrel-hardware/barrel-extension-parts/ar-308-ar-style-308-extension-prod40776.aspx

 

 

[98Z5V]

Gonna have to go to a barrel maker.  Not typically an end-user task that can be performed correctly.  There will be precision measuring and machining involved, if you find a barrel maker that would take that job on.

[308kiwi]

Swapping barrel extensions is an extremely difficult job, you have so many factors to consider,

1...the distance from the breech face of the barrel to the front face of the locking lugs, (the length of the tenon on the barrel that sets your bolts locking lug clearance and/or the depth of the barrel extension), will need to be the same or if not the barrel will need to be set back and this clearance corrected.

2.....head space, especially if you have had to set the barrel back to get your lock up distance correct, this is actually the easy one as you can re-set your head space by simply running a chamber reamer in and re-cutting the chamber the appropriate amount deeper. 

3....now this is the tricky one, timing the gas port, the chances of the thread in your new barrel extension starting in exactly the same place as your existing barrel extension are so remote it's not funny, where the thread starts will determine were the gas port ends up when the extension is torqued up, the only way to fix this if it doesn't time up, (and I almost guarantee it won't), is to keep setting the barrel back a few thou at a time until it does, a time consuming job.

I'm not trying to discourage you, but these are the things you need to consider and if you're paying someone to do this for you it could well run well over buying a complete barrel assembly that is to the spec you are trying to achieve.

[rcromwell92]

Thank you, I just going to buy a new Barrel with feed ramps already cut.  Will it be an issue if the barrel has feed ramps but the Upper does not. Also, could I just have them cut into the upper? 

[98Z5V]

^^^  Not too big of an issue.  You can cut them in yourself, use the Dremel chainsaw sharpening bit.  It's the perfect size.

Here's a graphic of barrel extension-to-upper combinations, for reference: