I have a between the wars Win Model 12 in 16 ga 2 9/16 inch chamber with a solid rib and "mostly gone" finish. I enjoy shooting it, but the short chamber caused problems with ejection and the case mouths were blown to the point that reloading them was problematic. Therefore, I had the chamber lengthened to 2 3/4 inch. Now the case mouths are not as blown, but ejection is still an issue (about 20% fail to eject, holding up in the ejection port). Are there other parts that need to be changed or modified to allow use of 2 3/4 inch shells? Opening the ejection port seems to be an obvious fix, but I do not want to have this done if other part changes or modifications will solve the issue. Any advise is welcome and appreciated.