I put on my PRI low profile gas block today. Besides measuring and eyeballing the gas port on the block and on the barrel is there any way to make sure it is properly aligned? I just don't want to run into any problems.

And my personal opinion all threads are useless without atleast one pic, here she is so far. Just waiting for my Nikon Tactical and Larue Mount:

take the barrel off.  put it in an indexing head.  center the barrel.  take a drill blank and line teh barrel up in the indexing head.  take and index the barrel.  180 degrees. take a 3/16 ball nose endmill and put a divit on the barrel.  the hex screw will center on teh divit.  im guessing you wont have acess to this method.  i dont know of any other ways off-hand to do it cause i never had to do it any other way.  ill give it some thought though.

ETA. nice rig

Simple, measure it.

Measure from the edge of your new block to the hole.

Now draw a vertical line on the edge of the block with a pencil, in line with the hole.

The measure the same distance from the port in your barrel towards the reciever, draw a mark where the edge of the block needs to stop fore/aft on the barrel, and another line parallel with your barrel so you can match that up to the vertical line you drew on your block to make sure it lines up side to side.

Quoted: take the barrel off.  put it in an indexing head.  center the barrel.  take a drill blank and line teh barrel up in the indexing head.  take and index the barrel.  180 degrees. take a 3/16 ball nose endmill and put a divit on the barrel.  the hex screw will center on teh divit.  im guessing you wont have acess to this method.  i dont know of any other ways off-hand to do it cause i never had to do it any other way.  ill give it some thought though. ETA. nice rig

Beautifully elegant.  I wish I did have access to such machinery.