It came with a flash hider/compensator but it's not pinned. It slides on and then Allen key tightened. Is this legal? I could swear it is not. Please tell me I'm wrong

If barrel is not threaded and the muzzle device is not a flash hider, then it is legal.

A semi-automatic firearm should be considered to be "substantially identical," that is, identical in all material respects, to a named assault weapon if it meets the below listed criteria:

 

A. semi-automatic rifle that has the ability to accept a detachable magazine and has at least 2 of the following:

a folding or telescoping stock;

a pistol grip that protrudes conspicuously beneath the action of the weapon;

a bayonet mount;

a flash suppressor or threaded barrel designed to accommodate a flash suppressor; and

a grenade launcher;

 

You the detachable magazine and the pistol grip.

That makes a flash hider illegal, whether it's pinned or not. IF it's a flash hider.

We need pics of this muzzle device.

We need pics of this muzzle device.

This is it.

 

http://www.hi-pointfirearms.net/proddetail.php?prod=HPTS995C008

well it states compensator in the link, pending no threaded muzzle you should be good to go. 

Yeah, that is legal.

Woo hoo. Thanks a lot.

I just got one too on a barter. Shot about 150 rounds tonight and it was a lot of fun!