Hammering, hammering roll pins in AR lower...

[BumbleBug]

I just finished building my first AR lower & I'm pleased to say without a significant scratch! I used a PSA & parts kit. I bought high quality proper size punches at the hardware store & read tutorials as well as watched several YouTubes before starting. Here are a couple of questions.

The roll pin hammering was extremely HARD! I oiled the pins slightly to help. To get the pins in I had to resort to a heavier nail hammer & it took forever! I was pleased when I got the trigger guard pinned without breaking an "ear". But the bolt catch lever was another matter I had to hammer so hard the end of the roll pin started to mushroom, so much so, that when it got flush with the hole it had to "scrape" it's way in to be just below flush.

1) Is this normal? Are there better quality pins, perhaps slightly smaller?
2) It was suggested that the buffer tube threads have a small amount of "AeroShell 33MS grease" applied(?) What's this & will any grease be ok? Why grease, seems like locktite would be more in order?

TIA...

...bug

 

[Ibmikey]

You should have put a bevel at the end of the pin to let it travel easier, don't pound on them use padded (tape) jaw vise grips or a small vice to push the pins in. Glad you and your nail hammer did not cause damage because the pins can be a problem. I mic the diameter to see that they will fit after being compressed in the hole. A good hardware store will have a pin assortment and I have measured with my micrometer before purchasing as they are roll pins and vary in size.

 

[Ibmikey]

I tried to edit vice to vise but no luck, anyway you know what I mean.

 

[MagnumWill]

If you plan on using Loctite on the buffer tube threads, make sure you don't use so much that it runs into the retainer hole. Just a dot or two would be sufficient.

 

[Ibmikey]

I missed the thread part, I have never had need to lube the threads and certainly would not use locktite. Just cinch up the castle nut and stake it in place, it will not come off when you do not want it and will if you have a need.

 

[Fishbed77]

I've never had problems with AR rollpins. I always start them with a roll pin punch, and use a C-clamp to press them in. Easy as pie.

Be sure to use a liberal amount of masking tape to prevent marring the lower.

 

[madmo44mag]

I had one lower that gave me the same problem but after I put a very slight radius on the pin it went right in.
Since then I started looking at the pins when I got a kit and noticed some pins have a slight radius and other don't.
When I get a kit with straight pins I radius them and never had an issue since.

 

[Knight cadet]

My dad uses a pair of channel locks wrapped in masking tape to press them 99% of the way in, then uses a punch to countersink them. He also puts tape on the receiver to protect it.

 

[HKFan9]

I do the same as mentioned above. I build a lot of AR's for myself, my family, friends, colleges and customers. I keep a set of channel locks in my AR tool kit wrapped with an abundant amount of Blue painters masking tape. I also use said tape to tape up the receiver. I also have a good quality set of both brass and steel punches, but a lot of times they are never needed.

In case of a slip up on my end I also keep a Birchwood Casey Flat Black gun touch up pen in there as well.

 

[Ritz]

If you can't tap a roll pin into place with a small rubber or brass mallet + punch using light strokes, either the hole is too small or the pin diameter is too large.

 

[rdmallory]

I use a needle nose vice grip to hold the roll pin together to get it started.


Doug

 

[ParabellumJ]

Never had an issue with roll pins. I use a hammer and punch and it's easy. As far as grease, I do use the aero shell 33ms on the buffer tube. The grease just helps the threads, but you could use Tetra as well. I got a small amount of the aero shell from umbrella corp for cheap and for $5 it will last my lifetime. You could also not use anything, the gun will still function fine. As far as lock-tite, I would not use it on an AR anywhere. Of course I stake my castle nut so it's not an issue.

 

[Justice06RR]

Roll pins should go in fairly easily without too much force. Usually the hardest for me to drive in is the trigger guard roll pin, but even then I'm not "struggling" to install it.

If you think you are putting too much force trying to hammer the roll pins, then they are probably not in spec. I've used PSA LPK's at least 3 times now and have no issues installing anything on the lowers (although I only use Spikes Tactical lowers).

 

[Tipsy Mcstagger]

Doug, the needle nose vise grip is a great idea! Is it pretty effective, a noticeable difference?

 

[Destructo6]

I had 2 roll pins act the same way in the last lower build. It was a Daniel Defense lower parts kit, which I assumed would be good to go.

The bolt stop pin was so tight that I had to cut it and drive the pieces out the way they came. The trigger guard pin was also incredibly tight.

Luckily, the local hardware store had roll pins that were the same length and snug, as they should be, but not absurdly tight.

 

[BumbleBug]

Thanks to all - I learned a lot!

After reading all the remarks in this thread, I think I was a victim of oversized roll pins forced into undersized holes. I definitely will "mic" my stuff when I attempt another. People on YouTube claim they can gingerly put together a lower in about 30 min. I was at it several hours trying not to mangle things up! I learned a lot in the process & some great tips here at TFL.

Now on to the upper...

...bug

 

[Justice06RR]

Yes, the stripped lower should be pretty easy to do even with basic tools. It should take you around 1hr or less depending on your skill level and what parts you are installing (aftermarket add-ons).

I usually save the bolt catch installation for last, just personal preference.

 

[Mobuck]

Many/most of the current LPK use spring pins that may not be properly sized. I use 5" ViseGrips to squeeze the pin while starting it which works well. Using an incorrect punch is the worst issue and will cause the pin to swell. Running the correct size drill bit through the holes will remove finish residue or polishing burrs(especially in the trigger guard strap since it shouldn't be tight on the retaining pin anyway).

 

[Louca]

Bug, good thread. I am just at the point now in my build where I will be doing the things you mention. After reading this thread, I think I will try to use a pressure mechanism like a C-clamp to press the pins in instead of hammering them.

On mic'-ing the pin and hole, how much interference is too much? On the trigger guard, I tried to hand press the pin in the hole and it seems very tight. I am guessing it is supposed to be that way since it shouldn't ever fall out. But how much of an interference fit (i.e. pin O.D. minus hole diameter) should there be? Maybe I'm getting too scientific with this?

Lou

 

[Louca]

Yep, started the pin with a punch just to get it started, then used a C-clamp. Was so easy to do, smooth, fast, and no worry of it slipping off and scratching something. But did have to do the final sinking with a punch.