I just placed an order for one and I was curious to see if the bullet guide was hard to install on one?

Fairly simple. Just make sure to GO SLOW. Place the bullet guide in first, and very carefully mark where you are going to drill. Use a center punch to make a divot, so the drill bit does not slip when you do drill. Make sure to drill down straight. Tap slowly and back the tap off often to keep shavings away. Use lots of oil so the tap never goes dry. It's like sex. Sure you can go in dry but look how that's going to turn out! But seriously, lots of oil.

reply #2 is correct but take a look here... some guys put the tap in the drill..LOL

 

Well, definitely make sure you a center punch to make a divot and then check that this is still centered with the bullet guide in place. I guess my hole was off and I had to make some adjustments to the bullet guide. A big PITA. I was really worried when I first fired it post adjustments that the bullet squeezing thru my adjustments would have destroyed the gun.

Well guess its good that the company I work for also has a machine shop in house.

After drilling through can you feel the sudden drop off before hitting the lower receiver or do I just have to know when to stop?

You will know when to stop. Don't drill thru the lower receiver. Below is the link that CSS has of the install.