DIY Low-Profile AR-15 gas block

[Sam1911]

I've seen this on line and figured I'd try it myself. As I'm planning on a MI light weight float tube for this build, I needed a low-profile gas block and to get rid of the existing sight tower. I could buy one, but that costs money, and I already have a nicely pinned gas block fit to this barrel...

Existing middy barrel:

The pins came out easy and the block slid off with a couple gentle taps.

Cut off wheel in a 4-1/2" grinder made fast work of the bayonet lug:

... and the tower...

 

[Sam1911]

When you get to trying to clean it up, it becomes really apparent how rough these castings really are.

It's a little tricky to get even looking lines with the grinding belt when the casting wasn't very even to begin with.

But it doesn't look bad on the barrel again.

And after blasting and a bit of GunKote, it will be better than new.

 

[Sam1911]

I tried to give the leading edge a bit of a swept back look, just for aesthetics. Not that anyone will see it under the tube, but I'll know it's there.

 

[Sam1911]

A bit more looking on line got me thinking about how maybe those "corners" might touch the insides of the MI rail, as they're really slim and there's a channel for the gas tube which the block kind of needs to fit up into.

S back to the grinder...

Terrible picture, but it does show the new shape:

And, when you have a buffer, everything needs to be buffed to a shine.

Of course I'll sand blast it before GunKote, but its pretty to look at for now.

 

[CLP]

Guess you guys up in PA have thunderstorms this weekend too. Nice job btw.

 

[ifit]

That's awesome thanks for sharing

 

[Theohazard]

That looks really good. That's a lot better than any of the other DIY jobs I've seen. If I had the right tools I'd probably try that instead of buying a low-profile gas block next time.

 

[Sam1911]

Hey, thanks guys! It helps to have some pretty decent tools for shaping metal. Makes a picky job a little easier.

 

[119er]

Good job, should work nicely. You saved money and added pride in ownership, not to mention getting to tinker a while. I just did a light weight build with MI Gen2 SS HG myself. Found out the hard way that the clamp on style Vltor .625" low-pro gas block wouldn't fit. A BCM set screw style fit just fine though. BCM dimples their barrels for set screw location, which I was unaware of at time of purchase.

Here's Bushmaster's take on it. Just hacked off the tower and left a lot of needless material. Off of a dissipator carbine. This thing plus a full pinned front sight at the end of the HBAR barrel made it handle like a cinder block.

I'd be interested to know what yours weighs in at.

 

[Sam1911]

Yeah, I was going to do a dissy, but ended up with plans for lighter weight to a degree. I've still got the standard mid-length barrel, so it isn't super light weight, but the new 15" M-Lock rail should help keep the weight down. I think the rail is just at or just under 10 oz.

I consiered sending the barrel to ar15barrels.com to have it profiled down further -- still might -- but I probably don't really need to go to that extreme.

 

[docsleepy]

Looks very nice!

 

[MistWolf]

That's one of the best trim jobs I've seen. Very well done!

 

[dprice3844444]

send it out for a melonite dip

 

[cbob1911]

very nice. here's how i did mine:

 

[Sam1911]

send it out for a melonite dip

Well, actually I was thinking that if I did send the barrel out for re-profiling, I could get it all parked to match. Melonite seems a bit much doesn't it?

 

[chicharrones]

Nice work on the gas block.

 

[MachIVshooter]

Looks nice and light! Good job hand profiling the radius, too. I'm lazy these days; I'd just clamp the sucker to my rotary table and mill it.

 

[ThePenguinKnight]

The one I did for my wife's rifle doesn't look quite so pretty. But it functions great and is otherwise invisible under the handguard.

Still... now you've got me thinking how I wish it were all purty like yours... =P

 

[Bobson]

Looks great, thanks for sharing your work.

 

[Destructo6]

I did one of mine up similarly. All with a Dremel and Brownells MolyCote over it.

I spent more time than I needed as you really can't see it once it's under the hanguard.

I've seen too many set screw low pro gas blocks come loose to give up a good pinned gas block.

 

[Bartholomew Roberts]

Looks nice!

 

[Sam1911]

Got it GunKoted last night.

 

[Theohazard]

Awesome! What's the total time it took to do this project?

 

[Sam1911]

Maybe 30 min to do the shave and shaping, then another hour to sandblast, prep, and GK.

 

[greyling22]

wow sam, nice work. Far nicer than the one I did. Fortunately it gets covered up by a ff tube.
For those of you without great tools, it's a lot more work than sam made it look. I am a cheap cheap penny pinching fool, and I won't do another one. All I had was an angle grinder and a dremel. And BBQ grill paint. Actually far and away the hardest part was getting the stupid pins out and then back in. Maybe the brownells hockey puck front sight tool would have been helpful. I used a 2x4 and my foot.