1966/1967 1100 LT20?

[Virginian]

Okay, this edit is as a result of finding some info I had forgotten.
The first Lightweight 20 gauge Model 1100s were made from 1966 to 1970, and they were made on standard frames, with mahogany stocks and forends.
In 1970, the LW20 series was introduced. These guns are made on the same 28 gauge receiver as the later LT20 guns, but they have a symmetrical ejection port, and do not have the full length barrel extension going back into the receiver. And they have LW20 roll marked into the left side of the receiver.
In 1977 Remington introduced the LT20 series of 20 gauge lightweights, which remain in production today. They have the scolloped out ejection port, and the barrel extension is a 'full length' version, extending the full length of the ejection port into the receiver. The longer barrel extension and scolloped ejection port were to address problems which had occurred in some LW models. The LT20, as you might guess from it's 31 year production history, has been very popular and trouble free.