I upgraded my 15-22's firing pin to the Volquartsen.

I didn't know to use a brass punch, so my steel punch caused mushrooming on the firing pin roll pin. I used a brass punch without any problems.

From an AR15 build video I saw last night, I just learned about roll pin punches which have a dimple/protrusion that fits into roll pin hole. Those don't appear to be made of brass.

However, one of my friends, a retired engineer who admittedly hasn't built or serviced an AR, suggested that the roll pin punches somehow could cause the roll pin to expand outward, notwithstanding the fact that roll pins are made of softer material than, say the 15-22's bolt assembly.

For future AR15 builds and (hopefully not) any future 15-22 firing pin roll pin removals and installations, are roll pin punches a good thing to have?

Yes, roll pin punches are a good thing. The nub in the center helps keep the punch centered. So assuming you selected the correct diameter for the subject roll pin, it keeps the edge of the OD from potentially marring the hole in the gun.

If you look carefully at the tip of the punch, you'll find that the portion which actually pushes on the roll pin is just as flat as a "normal" punch, so cannot expand the pin outward - again, assuming you're employing the correct size punch.

There are a number of parts on an AR where a roll pin punch is the proper tool to use, including the bolt catch pin, forward assist pin, and trigger guard pin. Roll pin starter punches are handy as well.

Brownells makes one that is the best for the bolt catch pin, makes it much easier to install without damaging the upper.

Thanks.

For the 15-22, I *thought* that a 3/32" punch was the proper size for the firing pin roll pin, but, I forgot to mention, that only the 1/16" fit to drive the pin all the way in. What is the proper size roll pin punch?

Same question for the AR15 lower's bolt catch pin and trigger guard pin?

The Brownell's punch specifically for the bolt catch pin is 3/32". The trigger guard pin is 1/8".

15-22 bolt pins are supposed to be 3/32" as well.

I think the other thing to keep in mind, is that tool quality varies depending on manufacturer. A set of calipers will tell you if your punches are actually the size they are supposed to be or not.

There are many fields of engineers of which he is likely not a member of one which deals in any level of "fasteners". The purpose of a properly - sized roll pin punch is to prevent "mushrooming". Additionally, there are many applications where the roll pin is stronger than the items it secures.

There are "starter" roll pin punches that have a sized cavity on the end and are designed to slightly compress, or at least not allow the pin to expand, when struck.

They drive part way in, then you can switch to the dimpled version.

If I may, a COMPLETE set of the appropriate tools AND the shop manuals for any and all items one contemplates "fixing" as a neophyte gunsmith is a pretty good starting point. The cost of these items may very well cause hair loss at first, but will be recognized as a bargain every time you don't screw the pooch. (!!!!!!!!!!!!!!!!!!!!!!!)

Ralph Tremaine