I have an AR building guide and one of the tools in the photo looks like some kind of attachment that makes your punch longer.  It's for working on the lower.  I can't figure out what this is called.  Can someone help me out?

Probably a roll pin starter punch

Thought this was going to be a boxing thread.

I've no idea what you're on about though, do you have a picture? You should be able to do most anything on an AR with a standard set of punches. Roll pin punches make a few parts a whole lot easier, but nothing that I can think of requires extra length.

+1

Some people have used plastic electrical wire insulation to turn their roll pin punches into temporary holder/starter punches.

Longer the punch, the easier it is to break. Even a top she’ll Starret punch in the 3/32 or 1/8 range are considered consumable.

To get by, I have used old drill bits that are longer than the punches to remove roll pins with obstructions or are deep seated. Brownells sells roll punches that have half the shank milled away so they can seat closer to the firearm.

Roll pin starters and roll pin holders are really nice to have. One has a nipple on the end that inserts in to the roll pin to keep you from slipping off the pin. The other has hole in the punch that the roll pin fits inside. These work great for starting a pin. The only issue is if the pin is too short, it might not stick out of the punch.

Parallel jaw pliers and tape is much easier.

Truth

I watched a YouTube video a long time ago that showed how to build a complete AR15.  Bookmarked it, but the link doesn’t work anymore.  I assume it is one of those casualties of the new and stupid YouTube policies.  Anyway it showed a round  metal tube that fit over the handle end of punches that added length.  The assembler used it on a holder punch to start the bolt catch pin, then used it on a roll pin punch to drive that pin the rest of the way.  He said it is a custom piece that was built for him.  He mentioned that it was a length of steel round stock that was bored halfway through at an internal diameter to fit over his roll pin and starter punches so there was little play.  This gave him enough length to clear the lower receiver when installing that bolt catch pin.  I thought that was clever, but I never found such a thing commercially.  I didn’t look very hard for it and used other methods that have been talked about here on ARFCOM forever to install bolt catches.  That’s the only roll pin that such an extension would be used for, so I didn’t pursue it.

You can always take a "too short" punch and fit it in a deep well socket with extension (1/4" drive) - make it as long as you want - wrapping it with  electrical tape or plumbers Teflon tape to avoid marring the receiver - Also works with screwdrivers when you need more torque or length -

Yes. Truth.

Buy the little Crow Gunworks Bolt catch install tool. No tape is needed. A Toothpick is used as a slave pin. Unless you do something really dumb, it's impossible to mess up a lower with this tool.

The roll pin starter is perfectly sized to work as a gauge to see if the roll pin is oversized so you do t try to force in an out of spec roll pin.

It is better than vise grips, using a vise, or parallel jaws.

Looks amazing. Thanks for the tip.

What works best is what you are comfortable with, a lot of us older guys have been doing different than the younger guys for decades now and never mess a receiver up.  It just comes down to what you get used to.

I mean, I'm one of the younger guys, but I assembled two lowers with an extra pair of hands, a receipt, a ball peen hammer, and an allen wrench.

Managed to not mess either lower up and they're still putting rounds downrange.

Just comes down to how you learned to do it and what you are comfortable with, when I was in the service, we had the way the "book" told us to do it, then we had the way the old guys taught us how to do it.  Now I am one of the "Old" guys and just do it the way I was taught.

Yup. I went ahead and bought all the proper tools this go-around because I'll be walking a friend through building her first, so I wanted to make it as easy as possible on her. Actually building things with a viseblock and action rod should be much nicer than doing it on my living room floor or lap anyways.

I understand you point. Yes, a skilled person can use all the things I poo-poo'ed in my previous post and make a job look good and work properly. For many years I used a aluminum rods as starters and driving punches for AR bolt catch installs. I have used every common method and tool made for the AR.

FWIW, I could fall into either category. I'm only 40, but have I been a Gunsmith for a little over 15 years. Worked on thousands of AR's as a smith and teaching.

I have seen what people do to their AR using inferior and cheap tools, so unless something is cost prohibitive, I'll recommend tools that do clean work. The LCGW Bolt Catch Punch Set is one of those tools. It requires no skill, that's why it's great.

I can have a complete newbie assemble a bolt catch and it looks better then the job some factory assemblers do.

I have no affiliation with LCGW, just like their tools. I own about every AR tool and gauge made. Here are a few pics.

https://www.instagram.com/p/Bp_L5Bfny66/?utm_source=ig_share_sheet&igshid=1uruu6kkipoyd

https://www.instagram.com/p/Bp_L81XHzI9/?utm_source=ig_share_sheet&igshid=1nc73i5dyvx1p

https://www.instagram.com/p/Bp_O1OfHbkK/?utm_source=ig_share_sheet&igshid=1rnhvq611rmv7

Could I get a link to those Brownells punches?  Thanks.

I gotchu fam

It's more for removing than installing. For installation, I'd recommend some roll pin starter punches and double layered blue painter's tape on the receiver.

Roll Pin Holders

Roll Pin Starters

Starrett Punches

All have their place. That half milled punch SMM posted is the correct one.

Thank you gentlemen.

try the "walt's tool" from KAK also , it works pretty good and is cheap