Try the heavy piston and see if it will reliably cycle the gun with the target loads . it may be possible that the light piston is allowing excessive amounts of gas and carbon into the gas system .Score brand shells. I have also tried federal and Winchester with very similar results. I have used the heavy piston but for not more then a few rounds at a time, and only with heavier loads.
Shoot it "wet" with clp as "grouse man" says, savvy Remington 1100 shooters have been doing this for years!!!!
Try the heavy piston and see if it will reliably cycle the gun with the target loads . it may be possible that the light piston is allowing excessive amounts of gas and carbon into the gas system .
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http://www.weatherby.com/media/weatherby/manuals/SA-08.pdf
Have you thought of the recoil spring ?
The one that pushes the receiver back...you mentioned unknown round count .
Having cleaned the gun from the front end it maybe time to start looking at the other areas.
See page 5 of the Pdf file and the part #3.
Then go to Pdf page 8 ...
There are only so many things that can be wrong with it and you have covered most .
Rob
And you've cleaned the INSIDE of the gas cylinder, correct?
Yes, G96 is equally good.
No need to disassemble the piston.
I have to correct myself. I believe there is a rubber O-ring in that gun, in the cylinder, captured in a groove and very hard to see.
Because it goes over the threads for the magazine end cap each time you remove the barrel, I'm thinking that's really going to accelerate wear on that rubber ring. So for this gun I'll do the majority of the cleaning of the mag tube and piston with the barrel on and let the CLP do the majority of the work.



























