Gas tube pin on FSB

AR/M4 AR Technical Discussion
1

OK… I’ve put together a couple AR’s and never run into this situation before. I’m sure it’s a basic thing with a basic solution.

I purchased a BRT gas tube to reduce the gas flow a bit from a noticeably overpassed PSA barrel. Pretty excited about that, actually. The upper was mostly just function-checked; probably less than 100 rounds through the upper.

I am having difficulty removing the gas tube pin. I do have the FSB secured fairly well. I initially bent a weaver roll pin punch and figured it was cheap/no big deal. I ordered a brownell’s punch to replace it…and that has now bent, too, with barely any movement of the pin. I’m not an ape, nor am I a sloth. Is there a solvent I should try to break free from carbon or something?

2

Did you try going both directions?

I wouldn’t think it would matter since it sounds like you are hitting it hard, but did you check to make sure the hole isn’t peened and blocking it?

Might be worth sticking it in the freezer an hour or 2 then try driving it out.

3

Yes, I did attempt both directions initially.

By “peened” do you mean that the hole was somehow marked to partially cover “egress?” If so, I don’t see that.

The freezer is a good idea.

4

Maybe peened isn’t the correct term for what I was thinking, but yeah some distortion of the hole preventing the pin from sliding through. I suppose a burr could have been left inside the hole from drilling, but once again figure hits hard enough to bend the punch would get at least some movement.

5

What size punches were you using?

6

To drive it out, 1/16” roll pin punch

7

It’s time to get nasty with it. Instead of damaging punches, find something stronger with a narrow enough tip (big nail, screw, etc) to break that damned thing loose. Then go back to the roll pin punch.

8

That’s the wrong size. That hole is a 5/64th.

https://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/punches/mini-punches-prod8855.aspx?psize=96

9

Thank you for the assistance. Besides putting in the freezer for a couple hours, I realized that early last year I’d purchased Geissele’s gas block punch set. A couple smacks with the hammer and the pin dropped out.

On the 5/64 vs 1/16, what I’d read was to drive in with at 5/64 and drive out with a 1/16… I’m guessing that is simply wrong.

10

The 1/16 breaks because it’s incorrect. The punch I linked above is what I have been using for years.