Built my first AR this Spring and no problems. Standard 16" 5.56 SOPMOD stock etc....

Thought I would part together a 300 bkot pistol as funds became available. I already had a pistol length gas tube and picked up a DPMS low profile GB.

Here's my problem, may not be one but want to run it across you folks. I insert the gas tube making sure the feed hole is facing the correct way and hold the roll pin with a needle nose pliers and tap until started. Then seat it with a 3/32" punch and make it flush with a 1/16" punch. On the first build it worked fine.

For some unknown reason, I cant get the pin to pass through the second side. I dont think the tube it shifting because inside gas block port stays aligned with the opening in the tube.

Is my roll pin going in at an angle? The way it is now its solid but one side  of the block has about a 1/16" of the pin sticking outside and the other side is still the hole.

Should I not worry about it? It will be under a free float tube when completed.

I can supply pics if necessary.

Thanks for any suggestions.

JBL

If the pin is engaged on both sides and it's going to be under a handguard, I wouldn't sweat it aside from any OCD tendencies you may have.

I have found what works best is to insert a punch all the way through to align the gas tube and gas block holes. Prep the roll pin by grinding a slight angle on the starting end, use some lube and a rollpin holder punch (if you have one). Then "chase" the punch back out as you drive the rollpin in. When you nearly bottom out the roll pin holder punch, switch to your roll pin punch and drive in the pin until flush on both sides of the gas block.

Start it from the other side and see if you still have a problem.

Could be that the finish is just a little heavy on the one side.

If it is a split pin then it should squeeze down to the hole size and filing a slight taper on the pin will help it start easier.

Is it started in the hole on the other side? If so you might just have to tap it a little harder.

You could use a small drill bit or punch, as suggested earlier, to verify that the pin holes are drilled in a straight line with your gas tube.

Run a drill through the GB and gas tube assembled as a unit..  You are a victim of tolerance stack-up.

Sounds tike a plan. The roll pin is sized out at .081 but haven't found what what the hole is drilled at.

I would think if I got a 5/64" bit which is .0781 would work or do I need to drop to a 1/16" at .0625.

Thanks for any info offered.

JBL

The hole is 5/64". See if you can drive a 5/64"  punch all the way through, first. If not, as said before, drill 5/64" and put in your roll pin.
If you mess up the pin, any local Ace Hardware should have 5/64" roll pins. Buy one a little too long (1/2")  and cut to 5/16" long with a dremel tool.

Mission accomplished. Picked up a 5/64" bit.

I backed out the pin first then pushed through the drill bit with some difficulty.

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Tried tapping back in the pin but as you can see below, somehow it is shifting.

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Tapped it back out and put the bit into a drill and ran it back and forth for about 15 seconds. Tried again and went in like a charm. Just wonder if I opened up the hole too much. There is no play but wonder if it would be a good idea to put a drop of blue loctite on each side or would it fail from the heat.

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