First timer questions putting an upper together

Cucamonga

Cucamonga

One day at a time
Charter Member
Supporting Member
Joined
Dec 25, 2016
Messages
416
Location
Etowah North Carolina
Rating - 100%
4   0   0
Concerning fitting the barrel into the upper, should the barrel alignment pin easily slide into the upper slot or do they normally take some persuasion, barrel slides into upper without issue, just the pin not fitting into and seating in slot.

I don't have a upper vice jaws, any other methods work well?
 
If the pin just needs a hard push or light taps I would do so without hesitation.

For torquing the barrel nut you want vise blocks, Bev block, or reaction rod. You can do it without, I have, but it's pretty sketchy.
 
It depends on the upper & barrel, BCM uppers are a pain in the ass to get barrels to seat into.

I’ve done pretty much every sketchy process building ARs that you can find videos of on the web, a few you probably won’t find on there as well lol!

Now that I have the proper tools I will do 2 things to get the barrel to seat into “snug” upper, you can stick the whole barrel into the freezer over night and then before you get the barrel out of the freezer use a hair dryer to heat up the threaded area of the upper, a proper harbor freight heat gun is much faster though, I would not suggest using a propane torch because you can get things too hot and bad stuff “can” happen, but I’m sure someone here has gone that route.

Once you have the area where the barrel seats heated up go grab the barrel and then before you seat everything go over it with the heat for a couple of minutes and then seat everything, the barrel will hold the “cold” much longer than the upper will hold the heat so having the barrel out of the freezer for a few minutes won’t bother anything.

If you do not have a chest freezer large enough to stick the barrel in you can do the following.

Get a ziplock bag or something similar and cover the barrel extension, it doesn’t have to be super tight but you want things to be fairly water proof (ish).

Get a large bowel or a bucket and put a layer of ice on the bottom and then spread salt (ice cream salt is best but table salt works fine), stick the plastic covered barrel extension into the bucket and continue to layer ice & Salt enough to fully cover the barrel extension, the ice and water won’t hurt a thing but adding the salt will make things get much colder, much faster and as we all know salt water is bad for most metals and finishes, just keep that in mind when you’re doing everything and do your best to keep the salty ice/water off the metal, a few drops won’t be a disaster but you have to clean it off well and neutralize the corrosive properties of the salt before you seat the barrel, having it sit between the upper & barrel extension is no bueno, it normally takes 10-15 minutes for the steel to get cold enough to contract a micron or two, the upper will expand a little more than that so “most” of the time just applying heat to the upper will do the trick, if not use the heat & freezer/ice trick and you’re golden.

hope that makes sense and it helps.
 
Last edited:
The barrel went onto the receiver with light tapping using a wood block. I will be installing a barrel nut for the handguard rail so will need a 1 3/16" wrench for use with my torque wrench and it sounds like I also need a upper vice. Who is the low cost provider for these items?

This is a 9mm upper build, anything else needed. I've built a few lowers without any special tools, this is my first upper.
 
Since it's your first, some tips I've found over the years:
  • Don't forget a little moly grease on the threads if you ever want to remove the barrel nut in the future and to prevent galling
  • tighten to spec, loosen, retighten, repeat once more to properly mate the threads
  • upper clamshell style block or some soft jaws work fine
    • i wouldn't bother with a reaction rod. Some discussion here
  • if you don't have a vice yet, a cheap 4-5" harbor freight vice bolted down is fine for this kind of thing
 
You must log in or register to reply here.
Back
Top Bottom