What am I missing to finish my build?

My lower I got a full LPK including stock so that's taken care of.

My upper I purchased everything piece by piece so I think I may be missing some small things.

I got an aero upper that came with dust cover assembly, FA assembly, charging handle, and barrel nut with complete delta ring assembly.

Got a bear creek arsenal barrel 16" carbine gas system and dimpled

Used carbine gas tube with pin, delta ring, and flash suppressor with new crush washer.

Here is the barrel I got for it. I couldnt pass it up at the sale price plus i got extra off for being a veteran...     https://www.bearcreekarsenal.com/bca-ar-15-barrel-16-4150-parkerized-m4-contour-barrel-5-56-nato-carbine-length-gas-system-w-1-8-twist-dimpled

.750" FSB no pins or sling attachment

What small things do I need to put it all together? BCG is on backorder, why it's not listed.
I know I need pins and and other small things, just don't know exactly what to get or where to get it, or if it even comes as a kit which would be great.

What about the handguard/rail?

Coming with gas tube, just forgot to list it

A decent barrel

Complete LPK's usually come with a pistol grip and not a buttstock. If yours does include the buttstock, make sure it includes the receiver extension (buffer tube), action spring (buffer spring) and buffer. If it is a carbine length stock, you will need an endplate and castle nut for the receiver extension. You will also need a rear sight or optic and mags. In addition to all the required tools, don't forget consumables like grease and lube. Does your FSB require taper pins or is it a clamp on?

Edit to add: Handguard cap

This is the LPK i got...   https://blackrifledepot.com/anderson-lower-build-kit/

My rear sight i got on clearance here     https://www.primaryarms.com/aimsports-fixed-rear-sight

FSB I purchased through the EE. It comes with sight post and spring but nothing else. Listing mentions taper pins....

The gas tube and other misc fore end parts I also purchased through the EE. The parts would finish the upper, only small part that comes with is the gas tube pin and a new crush washer for the flash suppressor.

I just feel like there are small pieces that i am overlooking or does the upper just not have many micro parts like the lower?

Your lower build kit looks complete. If your FSB looks like this:

it will require taper pins, and the barrel will have to be drilled/reamed to make that work. Very few home builders are capable of doing that. Most (not all) gunsmiths are capable, but many people send out their barrel, FSB, barrel nut and handguard cap to companies who provide that service. Options for a drop-in handguard build would be to use a clamp-on style FSB or a set screw railed (for a front sight) gas block.

It does look like that. I have access to a drill press and other tools. Is there a "how to" guide for doing such work?

I found a really good YouTube video on how to do it. The FSB I will have is a used one so has the holes already drilled in it. Think that would make it easier to install on barrel either by drilling barrel, or using set screws?

Unfortunately, it is much more difficult to drill/ream a barrel using a used FSB than it is a new FSB with no taper pin holes. They are drilled/reamed as a matched set. This is how I search the site, using your issue as an example:" FSB pin reaming site:ar15.com " .Type that into your search engine (without the quotes) and surf away. Change your search term as you see fit. I personally would give my chances of success of using a pre-installed FSB at 1 in 4. A clamp-on FSB is much cheaper than 4 barrels. Good luck.

Source a virgin FSB.
Reach out to JT at Retro Arms Works. You won't regret it.

Well crap. Just spent $20 on the FSB last night. All the new ones I've seen are twice that. Guess it will just have to wait for now. Thanks for all the feedback!

Retro Arms Works will give you a quote, but just to give you an idea of the costs involved to do it correctly using a new standard FSB, it's about $100, including shipping both ways, to have your FSB installed on your barrel. A new FSB is about $30 plus shipping from Bravo Company . All parts (barrel, FSB, barrel nut and end cap) should be shipped by you to Retro at the same time. It helps to put your name on a piece of tape on each part. DEZ clamp-on FSBs (actually set screw) are about $35 plus shipping.

I've watched a video on how to do it and I'm capable of doing it, it's just if the already drilled FSB makes it harder to get good straight holes then I don't want to go that route and wasted $20.

Unless.... would make it easier if used the non-reamed side of the hole as drill guides? Or is the reason it makes it harder to do is that you may not have everything lined up perfectly and drill at a slight angle making the holes not line up correctly?

Just trying to weigh my options and get it done cheaply, but most importantly correctly. I would much rather drop another $30-40 on a virgin FSB than $100+ on a barrel.

Another idea, would it be possible to drill the holes a little bigger on FSB, thread all 4, and use screws and loc-tite until I can get the proper FSB?

BTW, the barrel IS dimpled already. I saw in the post above about dimpling the barrel for alignment purposes. As stated above, just thoughts running through my head of how to make things work.

I found virgin FSB f marked for 16.50 at numrich so went ahead and bought one