Autococker trigger plate differences

Autococker trigger plates 

There are four basic types of sliding frame trigger plates for autocockers:
Pre-98 with a slot
Post-98 with a slot
Pre-98 with a hole
Post-98 with a hole

First, we’ll cover the pre/post thing.  In 1998, WGP release a new style of trigger plate on stock cockers, along with composite 45 frames that fit them.  Most of the trigger plate profile was the same.  The tang at the top of the trigger plate remained the same, along with the front curve of the plate where your finger, or trigger shoe goes.  The things that were changed were the bottom profile of the trigger plate.  On the older plates, there were three flats, and a sharp point.  On the newer plates, there are two flats, and a blunted point.

Photo to come

A post 98 plate will not fit into a pre-98 frame, at all.  The added material forces it to sit above the top of the trigger frame.  
A pre-98 plate can fit in a post 98 frame, but it will be very sloppy, and the trigger will be allowed to rotate up and down in the frame.

So what’s the performance difference?  On a basic level, there really isn’t one.  On a fine tuning level, there is.  With a pre-98 plate, you could have a set screw sitting below the trigger plate, removing the vertical slack, and a rear trigger travel stop.  The vertical set screws would lift the plate up, and both reduce drag on the plate (smaller contact surface) and reduce the vertical slop in the trigger at the same time, while the rear stop would limit the overall rearward travel of the trigger.  That can’t be done with a post-98 plate because the trigger plate sits directly above the trigger return spring.  It's a choice between the rear stop, OR the rear guide screw, there isn't enough meat left for both without the set screws conflicting.  Is it a huge deal?  Not really, most people wouldn’t notice the difference unless it was pointed out to them.  

The other big change was the timing rod hole.  Before 98, stock cockers came with a three way that had a center body section, and two end caps held in by C clips.  The total movement of the three way shaft was less than was needed to cycle the gun, so some slack had to be built into the system.  That’s where the slot in the trigger plate came in.  Having a slot in the trigger plate allowed the trigger to move to the rear, lowering the sear, and then activating the three way.  If the timing rod had moved as soon as the trigger moved, it would have limited the trigger travel to the point where the gun couldn’t be correctly timed.  
One of the side effects of this setup was that there was more than enough travel, and in reality, too much travel.  That’s where the wide timing rods came in.  They took up some of the extra travel in the slot, but left enough for good timing.  They also acted as a trigger stop of the frame didn’t have one, which was a nice side benefit.

So why go to a round hole in 98?  Simple:  They changed the three way design.  
Why change the three way design?   Simple: It was cheaper to make both the three way, and the trigger plate. 
Instead of having the over travel built into the trigger plate, they built it into the three way.  By going to a simple tube for a three way, and eliminating the end caps, the three way shaft could move farther forward. That allowed the three way shaft to move with the trigger, and still allow for correct timing.