Originally Posted by woodnut
Phil3, IMHO, I think you should re-examine the 133 powder. Not having the proper burn rate does lead, among other problems, to short stroking and not picking up the next round. I'm no expert, but I do think that unless you found another culprit for your short strokes/failure to feed, the powder could very well be it.
I do recognize this, but was having the same problems with Hodgdon H322 powder. This and the N133 have similar burn rates, so both could be responsible for the short stroking. Both loads were starting loads, also possible contributors. I know of others who have used both powders in an AR15 without trouble, but will try slower burning powders to keep gas pressure high by the time the bullet passes by the gas port in hopes that will drive bolt carrier fully rearward. The H322, according to Hodgdon is even faster burning than the N133. I also have Reloder 15 and Varget, both notably slower burning, but perhaps too slow for the 52/52 grain bullets I am shooting.
Upon cleaning of the weapon, I found the bolt to be somewhat dry, which can lead to short stroking. I plan to take it out again freshly lubed and various loads of N133 and H322 to see what happens. I did not have any short stroking problems with Blackhills 223 Remington 55 FMJ ammo, but those were the first rounds I shot, and I did notice that the short stroking got worse over time, even though my hand loads were getting hotter. This is what made me suspect a gun problem. Also, surprisingly, the Blackhills showed pressure signs with flattened primers, ejector mark smears and impression from the extractor seam in the bolt face. My hand loads showed no such signs.