I started my 20" flattop build

[Big Frank]

I just got done cold-bluing the journal of the barrel and wiping the whole thing down with oil. I need to go buy more degreaser before I can spray paint it. I think I can get the muzzle device clean enough with denatured alcohol to blue it. No matter how it turns out it's going to be painted.

[Big Frank]

The barrel nut for the old free-float tube Is shaped like a puck with 20 holes through it that fit a G.I. barrel wrench. It also had 20 teeth on the front, just like the teeth a standard steel barrel nut has. I cut off that 1/8" piece and it looks like a little sprocket. I filed the barrel nut flat and was going to use some aluminum black on it, but the bottle was empty. So I painted it gloss black with a paint pen. I put the Can Cannon Threaded Port in its upper and screwed the modified barrel nut on to hold it in place. I held the barrel wrench in my hand and used it to snug up the nut. The threads on it allow attachment of the X-Fore Golf Ball Launcher, which previously was inside the main tube of the can cannon. I had to use both barrels, one inside the other to shoot golf balls. Now I don't.

They sell can cannon tubes and ports you put on your own upper. Then they started selling golf ball launcher tubes with ports and a 3D printed barrel nut, so you can mount the golf ball launcher without the soda can launcher, like I did with the aluminum barrel nut. Now they're selling X-Fore launchers with uppers that work without the can cannon, and it looks like they have a delta ring and standard barrel nut. Complete launchers for soda cans or golf balls are the same price. They don't sell the 3D printed barrel nut separately, but the X-Fore tube and port with the nut costs $30 more than the Can Cannon tube with a port and no nut. So that makes it a $30 nut, and I made mine out of what would otherwise be trash or scrap aluminum.

[Big Frank]

I blued the flash hider/compensator. The color is kind of spotty because you aren't supposed to touch it after it's clean. Fingerprints will mess up the finish, and I held it in my hand the whole time I was bluing it. But since it going to be painted over it doesn't matter what it looks like. I just didn't want to leave it in the white. It wasn't going to rust before I get paint on it, but when the paint gets scratched, I want the metal underneath as protected as possible. I used a lot of WD-40 to clean out the inside, and to lube it up. I managed to get most of the bluing off my fingers, so it probably won't kill me. I need to get dressed and go to the store for degreaser, so  can paint the barrel and comp tonight or whenever I'm in the mood. Then the whole upper will be ready to assemble.

[Big Frank]

I have McFarland-style one-piece helical gas rings in all 4 bolts, now. And solid firing pin retainer pins instead of cotter pins in all 4 BCGs, too. I was going to install an extended charging handle latch on one upper that doesn't have one yet, but I'm too tired and going to bed. I didn't make it to the store yet. Maybe tomorrow.

[Big Frank]

I couldn't spray paint or spray degreaser in the basement because I've been doing laundry all night and I'm still not done. Until I get it painted all I could do is dry fit the parts. The new jam nut is barely backed off the shoulder when the muzzle device is TDC. I'll probably clock it an hour from the 12 o'clock position so it pushes into my left hand when I shoot. The flash hider/comp and jam nut combined are 3" long, and the overall barrel length is about 22.25".

[Sponsor]

[Big Frank]

I put several coats of paint on the barrel and brake, one after the other. I think it will be okay if I let it cure for a couple days. But, let's face it, I probably won't wait that long. I didn't really plan on mounting a light on this rifle, but realized I had an extra mount and several flashlights that would fit it. I think you'll be surprised to see it later this week. I went to the store to get some food before the blizzard (?) hits tomorrow. The smell of spray paint was so strong I started sneezing as soon as I walked in the door.

[Big Frank]

Pics of top and bottom of barrel, top and bottom of flash hider. It looks like I was too close to focus on the last one. I had the flash hider screwed onto the shank of a drill bit covered with masking tape so no paint would get in the rear half. It was stuck on so tight that I held the drill bit in the vise and started unscrewing it, holding onto it with half of an old towel wrapped around it. The flat black got shined up from the towel but it doesn't have much paint on it. It's dirtier looking than before I guess. After a couple of turns I grabbed my barrel wrench (G.I. wrench only) and used that to unscrew the flash hider the rest of the way. I was spinning it around and around with 1 finger until it backed up the entire inch and a half. I took the tape off both ends of the barrel and gave it some strokes with a towel and shined it up to match the flash hider. It's a semi-gloss finish, like when you have a good coat of oil on Parkerized parts. There's enough paint built up on the journal that the new gas block needed a push to get started. It snapped back, right against the shoulder and will stay on if I point the muzzle down. I shook the barrel a little bit and it fell off, so it's not too tight and not to loose. I got the Goldilocks fit. I feel like going to bed, but might get it together in the middle of the night. I cut circles out of the Duck tape around all 6 screw holes on the handguard. I want to snug it down, metal to metal when I put it on, with no tape under the screw heads.

[Big Frank]

I wasn't sure if I was going to mount a light on this upper, and was leaning more toward not doing it. Then I remembered I have a M-LOK Offset Light Mount, Polymer (1st pic), and Light Mount V-Block and Rings (2nd pic) that I wasn't using. This combination does the same job as the Magpul Rail Light Mount, Left or Right (3rd pic), except it's a lot more compact, and costs $6.95 more than the rail mount light. At first I just put a free Harbor Freight flashlight in the mount. Then I realized I have a BUNCH of better flashlights that would fit.

I took the pocket clip and carabiner ring off my Olight Desert Camouflage Warrior Mini 2 and put it in the mount. I used my F.A.T. Wrench to tighten the screws down to 10 inch-pounds, maybe 15. I'm not sure but I thought it was only 10. The screws kept turning and turning and turning before the wrench finally clicked. This is how I crushed one of the Harbor freight flashlights. It's a good thing this light has the MCC (Magnetic Charging Cable), because the whole light is bent out of shape. I took the head off and the 18650 battery didn't fall out like it should. The body is warped so bad I had a little trouble screwing the head back on, but the light still works. It's 1,750 lumens max. and the beam distance is 721 feet (220 m) on Turbo. It will only run 4 minutes at 1,750 lumens before it steps down to 500 lumens for 206 minutes, then 200 lumens for 40 minutes. It will run 19 hours at 120 lumens on medium, and that's as bright as I normally use it around the house. If I click the tail cap it goes straight to Turbo instead of scrolling through the levels like it does with the side switch.

https://magpul.com/firearm-accessories/rails/light-mounts.html

https://www.olightstore.com/warrior-mn2