With an M4E1, it says it comes with the threaded roll pin for the bolt catch.

Besides that, does it take a standard LPK?  Does the threaded bolt catch pin work with any bolt catch?

Thanks

Yes and yes.
Geissele maritime bolt catch

Seconded. and just throw out the milspec bolt catch and get the geissele.  it is one million times better, in my opinion.

Gonna have to try those out, just got rid of my ASAPs anyway

Standard LPK absent the trigger guard. Forward Control and Lantac make nice bolt catches, but standard is just fine. The Geiselle one is just way to fugly and big for my taste.

Some grips come with a tab that fills in the void near the trigger gaurd, ie MFT brand of grips, so just have to make it flush.
It doesn't take alot of torque to strip out the threads from the bolt catch pin.
Once, I had to use a very small drill bit (turning by hand) on a m4e1 lower to clear the left over soft sand blast media inside the pivot pin spring hole.

Yes it works the same. I personally am not a fan of the huge ass Geissele bc. I actually prefer good ol' mil-spec.

Use a dot of blue locktite on that threaded roll pin