Denny here from Dennys Guns and GTS,LLC

I have seen a number of questions here on problems installing the roll pin that retains the gas tube in the front sight block so I thought I would share a couple of things we do at the shop.

1. Once we align the barrel nut or block for a free floater installation we install the gas tube and then slide a test bolt into place to check for proper alignment.

2. Run a roll pin punch of the proper diameter thru the gas block with the tube in place to make sure that both are aligned.

3. Brownells and others sell a nifty set of roll pin punches that have a hollow sliding collar that holds the roll pin on the punch while you align it and drive it home.

These punches are worth their weight in gold and  eliminate the hassel of trying to hold the pin when getting it started.  Also we have not lost a roll pin since using them.

4.  Once the pin, tube ect are assembled onto the upper, put in your charging handle and bolt, check for easy operation.  There will be some resistance as the carrier key slides over the gas tube, but it should not hit it.

5. You may need a final tweak to the nut go get perfect alignment of the gas tube/carrier key.

That's it.

If you are going to build more that one AR or change things around once in a while, GET THE PUNCH, money well spent.

Denny

That would be a pretty damn small hole to drill for the gas pin roll pin.  We got some good equipment but I would not attempt a hole that small.

Another very good reasone for using the punches with the pin holder is that the slide protects the finish on the lower as there is not contact by the punch, especially in the bolt hold open pin hole.

I have seen waaaayyyy to many ARs with nice gouges in the finish from roll pin punches.

Denny

DarkStar

Roger that.  I forgot to mention that we don't have a bolt in our test carrier.

I do use the charging handle to get the carrier back out in case of a slight mis alignment.

I agree 100% that the carrier should drop in under its own weight.  That is the key.

It is early yet and only one cup of coffee so far.
[:)]
Denny