I bought a Winchester 1300 - 20 gauge a while back from a forum member. It really looks like new! Today was the first time we took it out and I had a couple of boxes of cheap bird shot (7/8 oz.) and it would not cycle. It fires fine and was very accurate, it just would not cycle. One of the other shooters in the group said he thought the load was too light and these older Win Semis were made to cycle with a heavier load. like 1oz. I thought I would ask here before tearing it down and looking for trouble.

On a hunch I'm assuming you mean the old Winchester 1400. It should work and cycle fine with any standard target 7/8 oz. or target/field 1 oz. load. It's only chambered for 2 3/4" shells I think so it can't be that finicky.

 

Try disassembling the gun, and remove the gas piston in the forend and clean it and the tube thoroughly so that it moves freely inside. This is the area than gets gunked the most and it's not as "self-cleaning" as some of the newer gas designs made these days however the piston does have shoulders that serve to scrape carbon and keep the inside clean. But that exhaust crud builds up over time. Don't put any lube on the piston when you reassemble.

 

Manual courtesy of Steve -

http://stevespages.c..._winchester.pdf

Yes, 1400, thanks.