Gentlemen I am in need of some advice. I believe I have a headspace problem on my NM AR. I am getting pressure signs at very low loads, flat primers at as little as 22.4 grains of Varget, CCI small rifle primers, and 77 SMK's. At 22.8 grains I start to get light extractor and ejector marks. At 24 grains (normal load) I'm getting deep ejector marks. All spent cartridges have some degree of sooting. If I use the depth gauge of my calipers to measure the step at the end of the BCG / upper reciever it measures .012", taking same measurement while using a wooden dowel to push on the bolt face that number increases to .021" which is a difference of .009". I tried this measurement on another upper receiver and BCG I have and with or without the dowel it remains at .012". Swapping BCG's from one to another the measurements are the same, meaning the BCG that measured .012 in the second case will measure .021 in the NM upper. I can also see the bolt moving rearward when pushing on it with the dowel so it's not cam pin wear (which I also measured and changed out, I was thinking it could possibly be a stack issue). When I use my Hornady cartridge headspace gauge all spent casings measure 1.46" which is what they have always measured out of this rifle. I also tried the only factory ammo I have which is some LC 55 grain which yields, you guessed it, flat primers and ejection marks. I do not have access to a set of headspace gauges but am about to call Clymer and hope they have a set in stock.
Any suggestions will be greatly appreciated.