I am getting ready to assemble an upper for the first time and would like to know what the correct order of the parts is?

I have to unpin the gas block because it came pinned to the new barrel I bought and the barrel nut that came with the SLR rail wont fit over it..

So...install barrel...nut.
- reinstall gas block.  Should I install gas tube to gas block before or after I reinstall the gasblock  The rail is a SLR Solo.

I also have the flash hider to install.

If re-useing the same gas block, I don't remove the gas tube from the block. remove and reinstall gas block with gas tube still attatched.

No gas tube installed.  bought the barrel with just the gas block pinned from Ballistic Advantage

check out the tacked threads for info..

Which threads?  There are no tacked threads in this forum that I can see.

So...no one here can list the steps in proper order?

Like...
1. Install barrel/ nut
2. gas block
3....gas tube...When is the time to install? After barrel and gas block or install gas tube to block and then install block to barrel?  Barrel nut does not have to be indexed for tube.

4...flash hider...
5. ...rail

...and so forth...?

do you have all the parts with you now?  Just slide everything on and see what works.  it can all come back off.

You can try this order first.

barrel - delta ring - gas tube - handguard cap - fsb flash hider.

It is a flat top upper with a free float rail, AAC flash hider.

Barrel
Barrel nut
Gas block
Gas tube
Flash hider
Handguard

Either, it can be done either way.



So:



1: Insert barrel, tighten down barrel nut



2&3: Install gas block and then install gas tube -OR- install gas tube to block and then block to barrel.



4: Install muzzle device.



5: Install rail.





4 and 5 could also possibly be swapped parts and tools depending, again doesn't really matter.  The most important steps is installing the barrel nut before the gas block and the gas block before the muzzle device, since those are usually the parts that can't fit over each other.
 

Thanx gentlemen.

Thanx...was getting a few of these mixed up in my head.

The assembly order is going to depend on your parts.
With rails I use the gas tube goes on the block which is put on after the rail.
Obviously this would not work with a block that goes under the rail.
Unless it is a setscrew block and the setscrews are accessible through the rail.

If it is a stripped upper receiver be sure to install your ejection port cover before your barrel.  It is possible to install the ejection port cover after but it reqires jamming the cover hinge pin in backwards which is more difficult and you increase your chance of scratching your upper.

Some painters tape pretty much covers that problem.

Getting the port door on with the barrel installed isn't a challenge mechanically.  It is a challenge OPTICALLY, at least for some of us.  The real pisser is getting that silly little spring tensioned right when you install it.  The pin goes in from the rear, through the back of the port cover, then through the spring (get an extra turn on it to tension it right), and then through the front of the door and into the boss on the upper.  Now the fun: use fine needle-nose pliers or hemostats with lots of light and probably magnification to install the little C-clip.  It's a 1/8" clip, a standard size, but you can spend a few cents and get an E-clip, which is more rugged (and harder to bugger up).

With that said, it's still much less of a hassle to install the door before installing the barrel.  The process goes front to back instead of back to front as above, and you make sure the clip is on the pin before you start.  The spring is still the hardest part.

A lot of people have gone through listing all the steps for installing the barrel, but some of 'em haven't made it clear that you MUST torque your barrel nut before you ever worry about the gas tube.  Get that barrel nut notch really centered, and you'll have smooth sailing.  If it's a bit off, it's a royal pain to get the gas tube installed with some setups, and you could run into issues with the carrier key not sliding smoothly on the rear of the tube.  Once the nut is torqued properly, then the order should be self evident - anything that's going to be captured by the muzzle device goes on before the muzzle device, and in "chamber to muzzle" order.

Thanx for the help.  I managed to assemble the ejection port dover and forward assist with some bit of aggravation.

Once I received the large blue hockey puck from Brownells the unpinning of the gas block and then re-pinning it and installing the gas tube roll pin was actually quite easy.

I have mocked up the rest of the rifle (waiting on a torque wrench from Amazon for barrel nut and flash hider) with the barrel nut and rail and gas tube.  Put it all on my completed lower with bcg and CH and it actually hand cycles ammo perfectly from my mags.

Needless to say...very pleased with it.  As soon as I get my torque wrench I will secure the barrel nut with some ms33 grease and install the flash hider, re-install the rail and I believe it will be ready to test fire.