A friend and I tore down his fairly new 1100 for a good cleaning.
New gas system design then.
Just me, not a fan of this new design, prefer older one.
We run 500 rds without cleaning and the OLD "O" rings lasted a l-o-n-g time.
Hi round counts, fast, shooting skeet, and others shooting trap.
I "would have" guessed the problem being Win Promo target loads, as these are giving everyone fits, no matter the gun.
New Gun, check the ports, make sure "finished out" and no "protruding burrs" as we have seen in some new 1100s. [QC - ain't it great now-a-days?]
Check that newfangled gas system for burrs, and smooth.
Take a Blue magic marker, and do the inside of system in blue.
Some wear is normal, that which is not, will show on the rubbed off blue marker.
Use this to assist in finding what needs attending to.
New fangled gun lubes and solvents *sigh*.
Some of this new stuff is NOT good for rubber, (or anything else, other than wallet flushes).
Hot soap and water cleans those "O" rings.
Going back to when the earth was flat and this Came out, came out, Dexcron Automatic Transmission was found to be the ticket for Semi-Auto shotguns, and Auto Trans have rubber seals, gaskets and the like in them too...
ATF stinks, some get allergic reactions to ATF , so
Rem-Oil was not even a invented back when...
Browning Gun oil in a Tin Can, [ what I used] , Hoppe's Lubrication oil worked fine and dandy, as did Ballistol.
Later Kleenbore Formula 3.[I used this , still do ]
Oh, LSA worked/ still works.
Hoppe's No. 9 or Mineral Spirits cleans just fine.
Don't rub fingers opposite port, that "rail" is razor sharp
Stove pipe sounds like another problem, the targets loads used , should not be the cause, being in spec and having the "oomph" to run the gun.
Was the buttstock messed with? Factory has been known of late to screw up Recoil spring in there that up of late...
That QC thang going on ya know...
FWIW my '74 SX1, with "O" rings still going strong with 300,000 thru it.
My old 1100 with over 200,000 rds still churning and burning too...
Mine are not the only ones of these guns either.
<kicks rock, newfangled designs and all>