Regulated enfields in the US?

[RJW NZ]

I've got one like that, they are self-tapping screws which cut into holes drilled in the action to hold the forend tight onto the receiver.
I've also had one done with threaded inserts.

what about the others, there are two here that look like what you describe, the front most one seems bedded and not ever removed, a lag screw? And then at the bottom corner of the forend butt there's a dowel plug I've never seen before, any thoughts on its purpose?
And finally...what about that bridge over the front handgaurd? I understand a tightening purpose but has some clearance under it, so it would be loose, any ideas?

Lastly, whats it shoot like?