Some additional thoughts,
Slickhead mentions the last guns not being the same as previous trap grades.
When Winchester stopped production they decided they would make as many guns as possible from the parts department inventory.
Since they had mostly trap wood and trap & field full choke barrels they made trap guns. They used field receivers, with no engraving, and gold triggers from the DU & Mississippi guns. These guns were in the very late 88,000 & 89,000 range. The wood on all was very nice.
chugiakshooter mentions the firing pin spring. Yes it is strong and sometimes leads to a misfire especially with hard European primers. I cut 3 coils off and that corrects that issue.
superxjeff mentions the magazines. Yes, the SX-1 never came with a stainless magazine. The trap and skeet guns did come with chrome plated tubes except for the very, very early guns.
The magazine spring retainer is a loose fit in the stainless magazines because of a thinner wall. I use a Rem 1100
retainer as it is a bit bigger in OD.
Action springs, Forgot to mention them. When new, a standard spring is 30" long and after extended use they sack and it is best to replace them when they get to be less than 24". Also store the gun with the action closed.
It is critical to never use after market, action springs that are not reproductions of the OEM spring. They cause malfunctions and most important is the HD ones cause malfunctions and major failures. I have repaired guns that had these springs and had broken the bolt links and even sheared the gas shroud off of the barrel. They slam the bolt into battery with way too much kinetic energy.
CT