First of all, I really hope you're not actually pulling the trigger on a hot chamber knowing that the bolt isn't fully in battery.
Second, you've got a hodge podge of parts from all sorts of manufacturers most of which are middle of the road. The chance of unreliable function is much greater.
Did you check headspace?
If so, did you build up the go gauge with scotch tape to get precise measurement?
If not you need to measure some fired brass at the very least that you know what they were sized to. Ideally verify headspace with go/no-go gauges and get a measurement using the tape method. It's best to do this with the bolt and barrel uninstalled and the ejector and extractor removed.
Did you check the bolt fitment in the receiver extension to check for any burs or rough spots before assembly?
You say you're gas block is tuned, how is it tuned?
What ammo is it tuned for?
Is it retuned or setting checked for other ammo?
How are you determining that the gas ring is tight?
Is the bore free of any rough areas?
Have you tried swapping the gas rings?
Have you tried the bolt in a different carrier?
These are all things I would check. If they're all good I'd start with the buffer and spring. It's expensive but the JP VMOS will let you completely tune the weight and spring weight if it's the issue.
Hi all, thanks for the responses. The bolt carrier slides in and out of the the upper smoothly into the barrel extension when the upper is pulled off the lower. The bolt on the other hand is really tight, even with CLP but I don't think it is the gas rings. I think it is the raised-ring just behind the teeth that keeps the bolt centered. I took some 2000 grit sandpaper to it very lightly and polished it and definitely improved its function. This rifle is intended to be a lightweight battle rifle capable of 1MOA or better, not a precision gun.
In regards to Redneckbmxer24; I did not pull the trigger intentionally knowing that the bolt wasn't fully in battery. I should have clarified. The bolt was fully in battery, but the bolt carrier was not. And I didn't realize what was going on until I got it on video. I did check headspace using a tape method and once fired brass with a piece of tape measuring .0045 in thickness, the bolt would not close.
The bolt is free of burrs, but I don't know about the extension. The gas block is tuned for surplus MEN 147gr Nato ammo which clocked at 2580fps using a magneto speed. I shot 148 rounds of it and had this hangup 6 or 8 times. I also shot 18 rounds of some old hand loads using Nosler 168gr CC over 44gr of Varget, which pushed bullets at 2635fps. Of those rounds shot, the bolt carrier didn't fully close one time but the bolt was fully locked up.
I have not swapped gas rings, the bolt or carrier into a different upper because these are the only ones I have on hand. Measuring OAL of the MEN ammo shows that they are all within SAMMI OAL. The 168 handloads I shot were originally made for a bolt gun and had much longer base to ogive, I had to single load in the magazines. These chambered without issue.
I am using a standard AR15 milspec carbine buffer tube with a JP Carbine-Length Extra Power Polished 308 Recoil Spring. As far as changing buffers, I originally ordered a Spikes T2 and quickly found out it was too long for the AR15 tube, which is how I ended up with a less than ideal Radical Arms AR10 Carbine Buffer (I believe it weighs 3.8oz).
At this point I am wondering if the parts need some wearing in because this was the first 166 rounds on the rifle, the extractor is TOO strong, the buffer is too light or there were problems with the ammo since it is surplus (that still managed to shoot sub-MOA).
