Whenever I see a pre ban ad they almost always say "no sear block".  I assume that has something to do with making it full auto?  Is it a block in the trigger?  Receiver?

Also, I assume post bans have these "blocks"?

Thanks

The term usually refers to a block of hardened steel that Colt devised in a lame attempt to appease the government.  It's attached with a hardened pin to the lower receiver, right above the selector.  It is supposed to make a machinegun conversion impossible by preventing installation of an automatic sear (factory or drop-in), or (I believe) even a Lightning Link.  It projects upward so as to interfere with the travel of an M16 bolt carrier.

You'll find that kind of sear block only on Colts.  Some other manufacturers have taken less draconian measures like leaving extra metal in the rear or side of the fire control parts well.

The post below is totoal different from what you're talking about right?

[url]http://www.ar15.com/forums/topic.html?id=22620[/url]