|Originally Posted By SSN_Doc:
Colt went to using larger pins on their receivers and triggers during the AWB. This was to make it difficult for people to install military and law enforcement only parts.
The benefits of using the smaller pin receivers, are that you can use any milspec sized replacement parts. Since every other manufacturer stayed with the original military sized pins, the greatest compatability with parts is with the smaller pin sizes.
Advantage of large pins is ...
Well I guess you got a pretty good chance that if you have a Colt it's all Colt.
Colt did it long before the AWB.