I built an 7.5" AR pistol with a upper setup I bought on the EE.  As it had a M1S pistol buffer and an RB Precision carbine tube, I went with the carbine tube.

The seller said it had a glitch or two but preferred hotter loads, so-

I  (like an idiot) opened the gasport to .093" before test firing it.  It came with a pigtail, but I figured a straight pistol tube would be better long term.  It has a regular car buffer and spring.

First trip to range (drilled to .093" and straight gas tube): 100+ degrees in the shade.  Wolf poly 62.  
Pistol fired 3 30rd mags just fine.  Looked good.  Next mag it fired two or so and lodged casi in chamber, stripping next round into stuck one.  After a trip to the shed with the range officer (I forgot my cleaning rod-smart.....) I had the case out.  Extractor ripped rim off case.
I tried again and got 3 or so off and same thing happened again, so I left.
When I got the round out at home I noticed that it had heavy carbon deposit on case neck.

I put the pigtail back on, and although I thought I had cleaned it when I got it, I really went at the chamber, letting it set with a Butch's soaked patch wrapped around my chamberbrush.  LOTS of black came out. After cleaning I polished chamber with a patch wrapped on chamber brush that had Flitz on it attatched to my drill (being careful of throat).  Three times and I think all the black was out.

Right before I went to the range the following day, I found my extractor to be easier to move by hand than it should be, so I got the proper size o-ring for the extractor spring and it was much better (very stiff).

At the range I fired 400+ rounds of Wolf 55 (old), SA M193 and some other 55 FMJ I had.  I ran 3+ mag dumps at just under bump speed.  The pigtail was a funny color, but the thing went bang every time.  The only failure I had with the beefed up extractor, pigtail and polished chamber  was 3 or 4 times the BHO didn't work on the last rounds.

I didn't hurt the throat because it would hit the 12x12 stell gong at 200 yards about 1/4 of the time (I'm still learning what hold works best) and the other 3/4 were damn close to it.

My question is- should I leave it alone or should I try to use the straight gastube and a H2 or H3 buffer.  Does the original case sticking problem sound more like a cruddy chamber/weak extractor or gas dwell problem and do you think a heavy buffer/ straight gas tube will work??
I'd really like to wind up reliable w/62gr M855 and 55gr M193 (and WWB and Wolf) with the straight tube. As I stated, the pigtail's now a different color and a tad different bend than before (was centered in my YHM FF tube before, now it's almost touching one side) and I hear they may rupture/break when hot (not good with the large openings of a YHM lightweight tube).

I know my mileage may vary, but I look forward to those who know chiming in.  

Once again Randall, thanks for the info.  I think I'll stick with the pigtail for now.

Plugging/redrilling may be the route I go.....I'm gonna send you an IM for some info.

Well, Randall got my barrel and had it at the correct size in a week for a very modest fee.  Thanks!

It ran fine this weekend, although with FederalAE 55gr it didn't actuate the BHO on 3/6 mags, but did just fine with the standard weight CAR buffer.

Thanks again AR15Barrels!