AR Heavy Barrel, Lots of Chips, and Weight Loss.

iH8DemLibz · Nov 23, 2015

It started life as a 24"bull barrel. Way too damn heavy and unwieldy.

So I decided to put it on a diet. Cut it down to 16-1/2". Still too front heavy.

The thirty eight 1/2" diameter holes removed 12 more ounces of weight. Now the barrel weighs 47 ounces and the rifle's center of balance is right under the front pivot pin.

With the addition of a Harris BR bipod, it should make a fine bench rifle.

protegeV · Nov 24, 2015

Nice work. Really went to town on that thing!
What was the original barrel weight, about 6lb?

MikeTF · Nov 24, 2015

I'm impressed. Doing something like this has never entered my mind.

vinjet700 · Nov 24, 2015

you've been busy.... :innocent0

outrider58 · Nov 24, 2015

I'm wondering if you experience any POI shift from the original zero or if you'll have to rework your loads due in part to change in resonance. Can you update us?

Nice work, by the way. :thumbsup:

iH8DemLibz · Nov 24, 2015

Pro - 78 ounces or 4.87 pounds.

Mike - Thanks for the kind words.

Vin - Over 3 hours of mind numbing drilling, cleaning, and repositioning. A mill would have made it easier.

Out - Will do. I'm curious how it shoots too.

slowpoke · Nov 24, 2015

Looks great. I'm hearing Jack Johnson signing "Reduce Reuse Recycle"

jimbobborg · Nov 24, 2015

Aren't bench rifles supposed to be heavy?

iH8DemLibz · Nov 24, 2015

jimbobborg said:
Aren't bench rifles supposed to be heavy?

Is my choice in AR-15 barrel weight going to get someone killed too?

I thought it was just my advice in the "Design a tactical shotgun" thread that would get someone killed.

Happy trolling.

clandestine · Nov 24, 2015

I think the job looks good, especially with the limited range of the equipment you used. I can see some inconsistencies in the dimple spacing

Whats the wall thickness at the deepest point in relation to the bore? You have to be careful you don't get too thin.

1FastSS · Nov 24, 2015

Wow work of art! keep us posted how it shoots!

iH8DemLibz · Nov 24, 2015

clandestine said:
I think the job looks good, especially with the limited range of the equipment you used. I can see some inconsistencies in the dimple spacing

Whats the wall thickness at the deepest point in relation to the bore? You have to be careful you don't get too thin.

I would say.070-.080

Blowing out a hole would be the very definition of OH $HIT!

And there are most definitely inconsistencies.

My calibrated eyeball could only questimate at how thing were lining up.

BigDaddy · Nov 24, 2015

iH8DemLibz said:
I would say.070-.080

Are you saying the barrel wall is .08" thick at those holes?

alucard0822 · Nov 24, 2015

From basic barrel calculations, should be a minimum of .150 wall thickness just to meet .223's pressure spec ahead of the chamber(with a .224 groove diameter), the thinnest .625" lightweight barrels. still have a .200" wall thickness, if yours is really under .100", you will probably get hurt if you fire it, probably anyone else in proximity too, it's scrap metal. Chalk it up to a couple hundred $s worth of experience that luckily didn't send someone to the hospital.

iH8DemLibz · Nov 24, 2015

It's .080 at the very bottom part of the hole. The drill bit has a lot of taper in the cutting edge. From the tip of the bit to the outside edge of the drill diameter is .165

.080 + .165 = .245. So the hole wall thickness runs from.080 to .245 along the taper. And the holes are nowhere near the chamber. So no concerns there.

Not to dash anyone's thoughts of utter failure and destruction, but I shot it today and it worked fine. No holes opened up. And I still have all of my digits.

I can't speak for those around me though. As I was wearing hearing protection. And couldn't hear their screams had something happened.

iH8DemLibz · Nov 25, 2015

As mentioned earlier, here are some accuracy results just to get an idea of what the gun likes. 50 yards. 7 power scope.

I was beginning to worry until I loaded up some PMC Bronze. For those who think ammo is ammo is ammo. It ain't. Most firearms like a particular cartridge.

That shot gun pattern in the center is Federal XM193. The stuff in the green ammo cans. With 30 rounds per cardboard box loaded on stripper clips.

The American Eagle comes in second place.

smokey · Nov 25, 2015

Steel has a lot of inconsistent internal stresses even in a quality barrel. When manufacturers remove metal from a barrel, they'll often takes steps like cryo-treating it to reduce how these stressed have been changed. Steel is also prone to have intense localized stresses at angular points that can lead to failure over time. It's why knight's fluting is hemispherical and other fluting has a nice radius on it. It's also why ejection port cutouts need radius'd corners and the origins of cracks need to be drilled to stop them from propagating. I can't see how sharp that point in the center is, but hopefully it's not too angular with how thin the wall is there.

I'm interested with the metal removed what happens when it heats up/cools down. My guess based on how internal stresses have been changed is that it would warp and change POI, losing true. Do you have any runout gauges to see if the barrel has warped one way and/or another?

I'm thinking a good way to go if you want a lightweight barrel is this guy...
http://www.ar15performance.com/inc/sdetail/11562/20639

smokey · Nov 25, 2015

iH8DemLibz said:
As mentioned earlier, here are some accuracy results just to get an idea of what the gun likes. 50 yards. 7 power scope.

I was beginning to worry until I loaded up some PMC Bronze. For those who think ammo is ammo is ammo. It ain't. Most firearms like a particular cartridge.

That shot gun pattern in the center is Federal XM193. The stuff in the green ammo cans. With 30 rounds per cardboard box loaded on stripper clips.

The American Eagle comes in second place.

View attachment 164660

That's 50 yards?! Dang homie, that barrel's jacked.

outrider58 · Nov 25, 2015

Did zero move at all? Good on you if not. Either way, nice job.

iH8DemLibz · Nov 25, 2015

I don't think the barrel is trashed at all.

As for heating up and warping, we'll see when I take it out next the time and shoot it cold.

I am completely happy with the PMC and will buy more of it.

I am not happy with a gritty 5-1/2 pound military trigger and shooting off a sandbag. Not conducive to accurate shooting.

Ya'll have fun busting balls.

AR Heavy Barrel, Lots of Chips, and Weight Loss.

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