Kurt, good inputs, thanks. I will buy a reamer.

Mark,

I used a bubble level and the Badger Ord gauges. I don’t have a $200 machinist’s level, but a metal 3” level that is quality enough for the job. I remeasured the alignment this morning. The bubbles were not “dead nuts” to each other. Using the rear gauge as a baseline, I had to raise an edge of the level with a .007 feeler gauge on the front gauge. The gauge is 3” long. I did the trig and .007” over 3” is 8.02 minutes (the barrel is under indexed). So I should be well within index tolerances. Also, I have at least .008” clearance between the inside rear of the hump and rear sight base (from Dan’s post above). I know Kuhnhausen says do not exceed 15 degrees hand tight, but the McKee book (pg 63) looks for 7 to 8 o’clock (30-60 degrees) calling 7:30 (45 degrees) ideal. A significant departure from Kuhnhausen! A discussion on this topic a few months ago had the consensus that 60 degrees was too much but I think under 45 was workable.

I feel I can confidently rule these things out: Barrel indexing, gas cylinder, op-rod, lower band, front hand guard.

My problem is this barreled receiver combination and any op-rod placed in it (4 so far now). I gauged the track channel and it specs out fine. Friction occurs during the last half inch of travel when opening the op-rod. I cycled it out in bright sun today and found what I think may be the biggest point of friction: the forward most part of the receiver. It looks like the bottom of the op-rod handle (the thin side) is bearing down on the flat surface beneath it just above the receiver pin/receiver drawing number area. I am now thinking perhaps the barrel is indexed correctly but perhaps TILTED down, causing the op rod to bind at the saddle/barrel area and op rod handle as it gets fully retracted.

And now the rest of the story—the shop press I used had the center of the press about 5” away from the edge of the bench. This did not allow me to center the press on the middle of the barrel vise and still have clearance off the bench to spin the receiver wrench. This caused me to pull the barrel vice out (towards me) until I had enough clearance to spin the wrench. When the press clamped down on the vice there were more pressure on the rear (far side) of the barrel vice, causing the vice & barrel to tilt about 5 degrees muzzle low. I knew this was not ideal but had no other option at the shop. I was careful when applying force to the receiver knowing I couldn’t pull the wrench perpendicular to the floor but had to be perpendicular to the barrel. I was careful and deliberate. The two other receivers I barreled that day in the same manner both pass the tilt test fine (they did not require as much torque, however).

Has anyone heard of the barrel being tilted down (muzzle low) during assembly and then this type of op-rod problem occurring? It's what is making the most sense to me right now, but I’m just amazed that the barrel would have gotten bent that much.

Thanks to all who have help so far. Gus, Roland, Dean, Ted or any other full-time smiths care to opine?

Thanks, Brett