I am changing my plastic handguard to a Geissele MK8. It came with the gas block. I just purchased the 2 drill bits from McMaster-Carr the PN in the instructions. Will the gas block come loose if I don't cross pin? I am going to dimple and set screw. Then blue locktite as per instructions.

Last question. Before I dimple how do I make sure I am 100% inline for gas port?

It is all together and looks great I just need to finalize the gas block.

Thanks

Personally I seat the GB against the barrel GB cut. Then take a drop of nail polish and put it on the tips of the set screws, screw in, unscrew, and remove GB. Dimple where the paint is.

Is this enough or does it have to be cross pinned?

The instructions give you the option of pinning, or not pinning, so one does not “have to”.

I chose to pin mine.

I mark the barrel with a pencil where the hole is and then line it up with the mark.  You could also use the set screws and test operation first and then make it permanent. 

That is my question.
How much abuse can it take before it gets loose? Are we talking war or just banging the rifle by accident or 2000 rounds and it has to be redone?

What was your method of pinning? Did you use a jig and drill press? Hand drill?

My BIL works in a machine shop, so I had access to a CNC for the simple cross drill hole.

I hand dimpled the barrel for the set screws, but still felt more comfortable to pin, even after locktight on the set screws.  Expansion and contraction might move the screws, so that’s why there’s the option to pin.

It would be easy to cross drill with a drill press as long as you take your time in a setting up a secure fixture to hold the barrel.  There is lots of room in the gas block and it also serves as a guide for drilling, so it’s pretty simple.  Lube well, use a high quality drill.

If you properly dimple the barrel and loctite the set screws you will be fine. Unless you are very harsh on your rifle. I like to use noveske barrels as they complete the pinning process for you. If your going to do it, do it right and visit Brdengineering and buy the jig. It will make life easier.