duuuuuuce

Negative I bought the complete lower and pieced everything else together. From what I have read there are many variations in .308 LPK so wanted to make sure it was correct.

I will measure it with drill bits and report back tomorrow. I could prob get pin gauges from my friend who does allot of machining but that will be the last resort. Generally speaking i shoild be looking looking for a .084-.086 hole on a 18" with a rifle system. Correct?

The lower was built by Aero, so you would think all that would be right and by looking at the buffer compared to a carbine buffer, the .308 one is shorter. The spring has to be right because there is a BIG difference on the amount of force needed compared to a AR-15

My mistake by the feel of it it's closer to 1/4 of an inch.

Sounds like a plan. I figured the length would affect it. I don't think I will have to go up as much as he did as if I lubee the poop outta it will barely eject the 149 grain stuff but won't grab another bullet. The match 168 will eject and grab another bullet just not lock the bolt back. The 178 functions correctly. I'm gonna try to get out to the range tommorrow and will report back. As long as the rain holds off.

Also the port is beveled like they didn't drill it out all the way or it might is supposed to be like that.

Yes and the bolt did lock back with the Hornady 178gnand is very lax to do it manually, has about an inch of play between the catch and it all the way back. The buffer weight is smaller than a normal carbine buffer and spring much stiffer than 5.56 so I'm sure they are correct parts. I pulled the gas tube and handguard. Here is a pic of the gas hole on barrel. It's even beveled and is much smaller than the opening on the gas block I would say almost half the size. I'm gonna check it and drill it out. I have gone through everything and now that other people have had problems with X- Caliber I'm leaning toward that being the problem. If if it was a 600$ top of the line barrel it would be the last thing I would check but I'm thinking what JT said is correct.

I looked through that thread, I'm gonna pull the barrel and take it down to my shop where I gotta a drill press and have at it, that has to be the issue. When you are saying #44 and #45 what is that. if it's something like 7/32's I get the .084/.086 by just dividing the two numbers right? Was never to good at math. :)

Thanks for replies I'm thinking the barrel is undergassed here are the pics of tube coming into upper from the looks of my 5.56's it looks dead on.

Thanks! Might as well post a pic of it. Have a 3-9 rifle scope but gonna get all the bugs worked out before it goes on. So just an ACOG I had laying around.

Hello all, This is my first post here but have been reading and trying to figure out my problem for a few days. This is the first .308 AR build I have done, but have accomplished multiple 5.56 builds. Anywho, on to whats going on and the details about the rifle. Yesterday on Christmas my uncle and I snuck out before out family dinner to get some range time and see how my fancy new 308 would fare. Not to good. I am use to running general milsurp 5.56 and wasn't aware that these .308's could be as finicky as it has proved to be. When we got out there I had some Federal 7.62x51 149gn and was running the rifle relatively dry. I lubed the bolt before I headed out but that was it. After the first shot the spent casing didn't eject. I tried to pull the charging handle back to get it out of the chamber but that was a little harder said than done. Finally got it out and round after round proved to do the same thing. A couple rounds made it halfway out with the case lodged between the bolt and ejection port. I looked at it and figured out that the case seemed a little tight in the barrel chamber. I got my cleaning supplies out and lubed the crap outta the chamber. After the chamber was lubed it started to eject the spent casings but not grab another from the mag (short stroking). All I had was that cheap federal ammo so we decided to call it a day and head over to my grandparents to get some food. Today I headed out again, but after reading figured I would try all the suggestions that I have read. I had the chamber and bolt dripping with slide guide. Also I picked up all .308 match grade ammo. 168gn Federal Sirrea Match, 168gn PPU match, and lastly some Horndady 178 Super Match. Also brought an AR-15 buffer spring for shits and giggles. Had puddles of lube in the chamber and excessively on the bolt. Finally the rifle started doing what its supposed to, I had NO short stroking issues today, but the 168 match wouldn't lock the bolt back after the last round was ejected. I used Pmags and CPD metal mags. No luck. I then just loaded a couple round of the Horndady 178gn and finally it did the unthinkable. Last cartridge ejected and bolt locked back. AWESOME. Now I don't want a rifle that can only shoot $1.00+ ammo per round. I have read that after they have a few hundred shots through it they start to get broken in and can then eat the lighter grain bullets. I don't really want to shoot 500 rounds of the pricy Horndady though it, but I will if I have to. I am thinking about opening up the gas hole on the barrel just a tad to see if it don't help any but what are your guys thoughts. The gun is Aero Precision Lower (built by aero and from the looks of everything, feel of the spring and all the buffer tube components are correct) Aero Upper X-Caliber 18' .308 win barrel with rifle length gas system. Aero Precision Black nitride bolt. YH low pro gas block (100% sure it is aligned and barrel as detent on bottom to assist in lining it up) Standard AR-15 rifle gas tube. After inspecting everything there are no signs of leaks or anything blocking the gas tube. They gas tube appears to be the correct length. Do you guys think I should open up the gas hole on barrel just a tad or wait till I get a few hundred more rounds though it? Thanks -Chris.