Acquired a older Remington 1100 20 Gauge Magnum today and the barrel has AXL 7 stamped on left side at receiver. I have looked at several sites trying to find correct date of production but it seems confusing at best. I'm also curious to difference between Lt Magnum 20 and Magnum 20. Any advice or help would be appreciated. I'm trying to put a value on this gun. Thanks in advance.