Sears, are they the same?

Hi all,
I opened up the old no1 mk3 bsa, one that on the outside appears to have led a sheltered life, to get to the bottom of a crunchy trigger, and lo and bebold, the sear face for the trigger has a considerable groove across it and on the sides of the 'pad' the metal have spread out in a little flange of their own.

Over in the little parts boxes I have half a dozen spare sears, several have little shoulders on the sides, where the pressure areas are, and also by the pivot point. Others have none of these shoulders and have simple squared sides. The external dimensions are all the same.
Are sears the same to all enfields, and are the ones I have with the shoulders from no1 mk3's?
thanks

They'll work in either rifle but the straight sided one is generally for the No.4. I see that my Ishapore 2A's sear is straight so it may the same with other late Indian rifles.

According to Stratton, the sear in the smle remained unchanged throughout its life. So they should be interchangable.

In his book on the No 4, he doses say the the sear spring is one of only a handful of parts that are interchangable with the No 1. I guess that means that the No4 sear itself in not interchangable.