Question regarding Remington 1100 20 gauge LW

[Virginian]

The L serial number prefix means it was made between 1968 and 1974, and since that is before the LT version was introduced the K serial number suffix which denotes lightweight at the end means it is a Model 1100 LW20, in other words a first generation Lightweight. Remington rollmarking is not something to bet a lot of money on. I have 3 barrels with no date code, and I have seen an 1100 with no rollmarking at all except the serial number on one. Between the standard weight 20 gauges built on the 12 gauge sized receiver, the LW 20, and the LT 20 models, the barrels will not physically interchange and bolt up tight with the exception you could put an LW barrel on an LT receiver, and it would work fine and be safe, but it wouldn't eject. But with the increasing value of LW barrels you are not likely to find one of those just laying around, and you have an LW gun anyway.
You have a good gun. If you shoot heavy loads, I would keep an eye on the buffer. You can get an owner's manual at www.remington.com that covers the LT20 which is very similar, and you can call Remington and I believe they will get you the exact owner's manual.

[Virginian]

If I had known you were from Virginia I would have added a smiley face.