Mdl1911a1 wrote:PyroRobby: this gun has the carbine length tube. On last night's disassembly I was specifically looking for misalignment, leakage, or damaged components from poor assembly. But everything checks as good. This is a 16" Bear Creek barrel ported at the carbine length, and the port is 0.0695"; or a tight fit for a #50 drill shank. Should I contact BCA?
If you think it is under gassing due to maybe needing a larger port size, then yes. BCA was very quick to get back with me when I had my issue, let me know it was covered by warranty and they would swap the upper or just let me send back the barrel. I told them I appreciated the support; but I was just going to resolve the issue myself, and I did. Drilling it will void the warranty, I didn't care, I wanted to fix it and not wait on shipping. Had a hunting trip scheduled.
A carbine gas system will have a smaller diameter gas port than a mid-length, and a mid-length gas port will be a smaller port size than a rifle length port. As the barrel length increases, along with the gas system length, the volume for the gas expansion increases, so the port needs to increase to have the mechanical pressure to work the bolt properly. With the increased volume, comes the need of a port size increase, due to a drop in pressure due to the greater volume containing the gas expansion. So, your port size of .0695 might be BCA spec. My port size I think is supposed to be BCA spec too at .089. However, from charts I have seen, googling AR15 gas port size chart, for me it would just be speculation. Somebody here likely can tell you more about what size port to expect than I can. Though my port was spec, nothing solved the short cycling until I shave .004" out of the hole, then it worked flawlessly. Of course if you plan to suppress the rifle then the port size might be fine with a suppressor.
You should have a 16" .750 diameter barrel and this chart says min is .070, I don't think it would hurt to go to .073, since the max for your call out is .086. I am not an expert though, just a nube really. Drilling the hole was easy, just remember to put a dowel in the barrel and take it slow and easy, if you go that way. BCA will warranty it though so, maybe just talk to them and do what feels right to you.
https://imgur.com/a/NIAs6jQ
Gun control is using both hands, good gun control is hitting your target precisely.