Frontpage
02-08-2008, 01:47 AM
Special thanks to forum member infrared35 (http://230grain.com/member.php?u=341) for providing us with this great front-page article based on his informative thread about building a "beater" AR-15 (http://230grain.com/showthread.php?t=1401).
http://230grain.com/images/articles/ar15brl/tn_arbblfinished.jpg
[Intro: Building the Beater]
I was one of the debatably lucky ones who got in on the Khalan Weaponry "five AR lowers for the price of four" deal a while back. The lowers took forever to come in and the quality was kind of spotty, but in the end all were basically functional, so I'm still happy. I decided to turn my last remaining lower into a beater carbine for equipment/ammo trials and for training.
Cost of receiver: $75
Previously, I had purcheased a 10.25" A2 heavy barrel pistol upper from a member of another forum to go on a pistol lower purchased through the Khalan deal. The upper was complete, but lacked a bolt, bolt carrier, or charging handle, although it did come with some First Samco railed handguards which were promptly transplanted to another AR. Since I had no other uppers to work with for this project and I wanted to upgrade my pistol to a flat-top anyway, this upper got commandeered for the beater rifle build. If I remember correctly, I paid $275 for the upper.
Total cost so far: $350
Subtracting, say, $100 for the pistol barrel which will be used on another upper, and subtract about $30 for the railed handguards which went to the other gun...
Total cost so far: $220
I shopped around for lower parts and found that one of the best deals without buying used or waiting forever for backorders was to get them through Sportsman's Guide using my secret member discount. I got a no-name 4-position collapsible stock assembly for $25, then added a DPMS lower parts kit for $40.
Total cost so far: $285
That left the bolt stuff. I had a bolt carrier with a non-staked carrier key sitting around that had cost me $50, and I ordered a brand new CMT bolt from Rainier Arms when it was on sale for another $50. A charging handle was $15.
Total so far: $400
I still needed a barrel that was legal for use on a rifle. I looked around for a while but every barrel I could find was over $100, even used ones. Finally, I stumbled across a machine gun rental shop in Las Vegas that was selling off used M4 barrels from their rental guns. They said the barrels were heavily used and no longer accurate, but I didn't care - most of the time this carbine would just be used for shooting blanks. Cost of barrel: $25.
Grand total for parts: $425
[Changing Barrels]
Now that I've patted myself on the back for building an AR with mostly questionable parts, let's get to the meat of the article: how to swap barrels out on an AR-15.
First, gather your parts on a beige carpet.
http://230grain.com/images/articles/ar15brl/tn_arbbls.jpg (http://230grain.com/images/articles/ar15brl/arbbls.jpg)
Assemble the necessary tools. You will need an AR barrel wrench, a thin punch, a small hammer (or a big one, I guess), a set of snap ring pliers, and some vise grips. If you've got an actual vise and a set of AR-15 action and barrel vise blocks, that's even better. Since I have neither a vice nor vice blocks, I improvised. Not pictured is a socket wrench to increase leverage on the barrel wrench.
http://230grain.com/images/articles/ar15brl/tn_arbbltools.jpg (http://230grain.com/images/articles/ar15brl/arbbltools.jpg)
Remove the bolt assembly and charging handle, then pull the handguards off.
http://230grain.com/images/articles/ar15brl/tn_arbblhandguardsoff.jpg (http://230grain.com/images/articles/ar15brl/arbblhandguardsoff.jpg)
If you look up front at the front sight assembly, you'll see that the gas tube originates from it and travels back into the upper receiver. In the center of the photo, you can see a small roll pin that goes through the front of the gas tube and holds it in place. You'll want to use your punch and hammer to tap the pin out. Don't lose the pin or else you'll be on the phone crying to your favorite AR parts dealer.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubepin.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubepin.jpg)
Once the gas tube pin is out, grab the gas tube and twist/wiggle it backward out of the front sight block. Depending on how dirty it is, this may take a lot of effort, and may even require applying cleaning solvents or penetrating lubricants. Only as a last resort should you grab onto the gas tube with the vise grips to help pull it out. Be extremely gentle if you use any tools on the gas tube itself, or else you'll be on the phone crying again.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeout.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeout.jpg)
There are a couple of ways remove the gas tube. Note the slight bend in the gas tube: The hole in the front sight base is lower than the hole in the receiver. You can rotate the gas tube 90 degrees so that the front of it clears the front handguard cap, and then pull the gas tube out the front. It may be easier, however, to just push the gas tube backward through the receiver. Again, be very careful not to bend the gas tube.
While the old barrel was still on the receiver, I decided to take the flash suppressor off. My barrel wrench has three differently-sized openings at one end to accommodate different flash suppressors. If your barrel was factory-assembled, the flash suppressor may be attached very firmly; in this case you'll either need to invest in a barrel block and vise route or just take it to a shop and beg them not to charge you $50 to unscrew a stuck piece of metal. I lucked out and was able to get the flash suppressor off the pistol barrel with only moderate wrenching.
http://230grain.com/images/articles/ar15brl/tn_arbblflashhideroff.jpg (http://230grain.com/images/articles/ar15brl/arbblflashhideroff.jpg)
Now you get to use the other end of the barrel wrench. There is a large slot in one end with three pins protruding around its perimeter. These pins engage the barrel nut as follows:
http://230grain.com/images/articles/ar15brl/tn_arbblwrenchfit.jpg (http://230grain.com/images/articles/ar15brl/arbblwrenchfit.jpg)
There is also a square hole in the middle of the barrel wrench that accepts a socket wrench for more leverage. You will almost always need the help.
http://230grain.com/images/articles/ar15brl/tn_arbblwrench.jpg (http://230grain.com/images/articles/ar15brl/arbblwrench.jpg)
Again, the barrel nut may be extremely tight depending on where it came from, who assembled it, and how dirty it is. Mine took a lot of wrenching. I ended up finding a lever of equal length to the socket wrench I was using with the barrel wrench and threading it through the upper receiver's carry handle (I guess it's good for something after all!). I knelt on one lever and pushed on the other. Nothing. Finally I grabbed one lever in each hand and braced the receiver with my foot. After some straining, grunting, and swearing, the barrel nut broke free. Once you've achieved similar results, unscrew the barrel nut all the way. The barrel itself should now come free from the front of the upper receiver; again, depending on how new or dirty the barrel is, it may take additional effort.
http://230grain.com/images/articles/ar15brl/tn_arbbloff.jpg (http://230grain.com/images/articles/ar15brl/arbbloff.jpg)
Once the barrel is off, take a look at the rear of the barrel nut and delta ring assembly. You will see a snap ring on the back, holding the delta ring and delta ring spring in place. Notice also how the gap in the snap ring lines up with the gaps in the spring and the delta ring, and also lines up with one of the notches on the barrel nut. This is, of course, where the gas tube goes through into the receiver.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubetunnel.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubetunnel.jpg)
Next, use your snap ring pliers to spread apart the snap ring and remove it. The delta ring spring and delta ring itself can now be removed. The barrel nut stays on the barrel unless you want to mess around with taking the front sight block off. In mil-spec units, doing so can be as painful as barrel removal.
http://230grain.com/images/articles/ar15brl/tn_arbblsnapringpliers.jpg (http://230grain.com/images/articles/ar15brl/arbblsnapringpliers.jpg)
http://230grain.com/images/articles/ar15brl/tn_arbbldeltaringoff.jpg (http://230grain.com/images/articles/ar15brl/arbbldeltaringoff.jpg)
Reinstall the delta ring, spring, and snap ring on the new barrel, then install the barrel on your receiver. You can see that there is a post on the barrel extension that fits into a corresponding notch in the receiver.
http://230grain.com/images/articles/ar15brl/tn_arbblreceivernotch.jpg (http://230grain.com/images/articles/ar15brl/arbblreceivernotch.jpg)
Now use the barrel wrench to tighten the barrel nut. There are probably specific figures out there for torque and such, but I just tighten it until two criteria are met: The barrel nut is tight, and one of the notches lines up with the gas tube hole in the receiver. After the barrel nut is tight, insert the tip of the snap-ring pliers or a similar implement into the gap in the snap ring and rotate it so the gap lines up with the gas tube hole in the receiver. Similarly, make sure the delta ring and spring line up. Now you can check the barrel nut alignment to see if you need to do more wrenching.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeholerear.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeholerear.jpg)
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeholefront.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeholefront.jpg)
Fit your gas tube back in place. This is usually done by putting the back of the tube through the delta ring assembly and into the receiver while holding the gas tube so that the bend is perpendicular to the floor (if the receiver is sitting upright), then rotating the gas tube so that the lower front section lines up with the hole in the handguard cap and front sight base. You can also insert the gas tube from inside the receiver, so do whatever is easiest. Now is usually the point at which you realize that the barrel nut and delta ring assembly only looked like they were lined up, when in reality you still need to do some fine-tuning with the barrel wrench. Regardless, be careful not to bend or dent the gas tube.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubebackin.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubebackin.jpg)
Fit the gas tube forward into the front sight base. Depending again how dirty your barrel is, you may need to clean the gas tube cavity in the front sight base. Ensure the gas tube pin hole is lined up. Find the gas tube pin that you made sure not to lose and gently tap it back into place. Note: there is a school of thought that says any time you remove a roll pin it should be replaced with a new one. I generally subscribe to this theory, but in this case I was building a beater rifle whose purpose in life is to be tortured. If the pin breaks after a hundred rounds, I'll order a new one and chalk it up to science.
http://230grain.com/images/articles/ar15brl/tn_arbblgaspinbackin.jpg (http://230grain.com/images/articles/ar15brl/arbblgaspinbackin.jpg)
Put the handguards back on. Insert the charging handle and bolt, checking for fit. An unusually tight fit toward the front part of the bolt's travel may indicate a bent or misaligned gas tube. Go back and correct as necessary. Install the upper on the lower and perform a parts check: Make sure you don't have any spare parts lying around (aside from the barrel you just removed). Now perform a function check: Cycle the bolt a few times, making sure it seats fully when released. Lock the bolt open, then hit the bolt release. Dry fire. Cycle the bolt again. Put the safety on and pull the trigger; hopefully nothing happens. Put the weapon back on fire. Dry fire, but hold the trigger to the rear while cycling the action once more. Release the trigger and listen for the click of the hammer releasing from the disconnector. Pull the trigger again. If everything works to your satisfaction, test-fire with live ammo. If you have blanks and a blank adapter, you may want to try those first.
Here's the final product: an A2 AR with an M4 barrel and a CAR stock. I'm going to use it mostly for training purposes, either with blanks or empty for simple weapon handling drills. First, though, let's take it to the range to learn just how shot out that $25 Las Vegas barrel is.
http://230grain.com/images/articles/ar15brl/tn_arbblfinished.jpg (http://230grain.com/images/articles/ar15brl/arbblfinished.jpg)
[Test Fire]
I took the beater out to the range for a quick test drive. With it went a 20-round Colt mag loaded up with 62-grain Wolf (in the older lacquered cases). It ran beautifully: not a single function issue.
Zeroing was done on a standard M4 target at 25 yards. First group:
http://230grain.com/images/articles/ar15brl/tn_P2050237.jpg (http://230grain.com/images/articles/ar15brl/P2050237.jpg)
It was a little on the large size and obviously not centered, but not too bad. A few clicks down and to the left produced the second group:
http://230grain.com/images/articles/ar15brl/tn_P2050238.jpg (http://230grain.com/images/articles/ar15brl/P2050238.jpg)
Moving one click back up and paying more attention to the sights:
http://230grain.com/images/articles/ar15brl/tn_P2050239.jpg (http://230grain.com/images/articles/ar15brl/P2050239.jpg)
There we go: all three rounds in the center of the zero target. The barrel can't be all that bad as far as wear goes. Now let's roll a target out to the 100 yard line and fire off the rest of the mag.
http://230grain.com/images/articles/ar15brl/tn_P2050241.jpg (http://230grain.com/images/articles/ar15brl/P2050241.jpg)
Again, not bad. All shots fell within the 5-ring at a hundred yards with iron sights, Wolf ammo, and my crappy eyesight, all with a barrel that was taken out of service at a machine gun rental range.
I predict that the first thing to give me trouble on this rifle will be the non-staked bolt carrier key. If I were going to dump more money into this build, that'd probably be the first thing I'd fix.
http://230grain.com/images/articles/ar15brl/tn_arbblfinished.jpg
[Intro: Building the Beater]
I was one of the debatably lucky ones who got in on the Khalan Weaponry "five AR lowers for the price of four" deal a while back. The lowers took forever to come in and the quality was kind of spotty, but in the end all were basically functional, so I'm still happy. I decided to turn my last remaining lower into a beater carbine for equipment/ammo trials and for training.
Cost of receiver: $75
Previously, I had purcheased a 10.25" A2 heavy barrel pistol upper from a member of another forum to go on a pistol lower purchased through the Khalan deal. The upper was complete, but lacked a bolt, bolt carrier, or charging handle, although it did come with some First Samco railed handguards which were promptly transplanted to another AR. Since I had no other uppers to work with for this project and I wanted to upgrade my pistol to a flat-top anyway, this upper got commandeered for the beater rifle build. If I remember correctly, I paid $275 for the upper.
Total cost so far: $350
Subtracting, say, $100 for the pistol barrel which will be used on another upper, and subtract about $30 for the railed handguards which went to the other gun...
Total cost so far: $220
I shopped around for lower parts and found that one of the best deals without buying used or waiting forever for backorders was to get them through Sportsman's Guide using my secret member discount. I got a no-name 4-position collapsible stock assembly for $25, then added a DPMS lower parts kit for $40.
Total cost so far: $285
That left the bolt stuff. I had a bolt carrier with a non-staked carrier key sitting around that had cost me $50, and I ordered a brand new CMT bolt from Rainier Arms when it was on sale for another $50. A charging handle was $15.
Total so far: $400
I still needed a barrel that was legal for use on a rifle. I looked around for a while but every barrel I could find was over $100, even used ones. Finally, I stumbled across a machine gun rental shop in Las Vegas that was selling off used M4 barrels from their rental guns. They said the barrels were heavily used and no longer accurate, but I didn't care - most of the time this carbine would just be used for shooting blanks. Cost of barrel: $25.
Grand total for parts: $425
[Changing Barrels]
Now that I've patted myself on the back for building an AR with mostly questionable parts, let's get to the meat of the article: how to swap barrels out on an AR-15.
First, gather your parts on a beige carpet.
http://230grain.com/images/articles/ar15brl/tn_arbbls.jpg (http://230grain.com/images/articles/ar15brl/arbbls.jpg)
Assemble the necessary tools. You will need an AR barrel wrench, a thin punch, a small hammer (or a big one, I guess), a set of snap ring pliers, and some vise grips. If you've got an actual vise and a set of AR-15 action and barrel vise blocks, that's even better. Since I have neither a vice nor vice blocks, I improvised. Not pictured is a socket wrench to increase leverage on the barrel wrench.
http://230grain.com/images/articles/ar15brl/tn_arbbltools.jpg (http://230grain.com/images/articles/ar15brl/arbbltools.jpg)
Remove the bolt assembly and charging handle, then pull the handguards off.
http://230grain.com/images/articles/ar15brl/tn_arbblhandguardsoff.jpg (http://230grain.com/images/articles/ar15brl/arbblhandguardsoff.jpg)
If you look up front at the front sight assembly, you'll see that the gas tube originates from it and travels back into the upper receiver. In the center of the photo, you can see a small roll pin that goes through the front of the gas tube and holds it in place. You'll want to use your punch and hammer to tap the pin out. Don't lose the pin or else you'll be on the phone crying to your favorite AR parts dealer.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubepin.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubepin.jpg)
Once the gas tube pin is out, grab the gas tube and twist/wiggle it backward out of the front sight block. Depending on how dirty it is, this may take a lot of effort, and may even require applying cleaning solvents or penetrating lubricants. Only as a last resort should you grab onto the gas tube with the vise grips to help pull it out. Be extremely gentle if you use any tools on the gas tube itself, or else you'll be on the phone crying again.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeout.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeout.jpg)
There are a couple of ways remove the gas tube. Note the slight bend in the gas tube: The hole in the front sight base is lower than the hole in the receiver. You can rotate the gas tube 90 degrees so that the front of it clears the front handguard cap, and then pull the gas tube out the front. It may be easier, however, to just push the gas tube backward through the receiver. Again, be very careful not to bend the gas tube.
While the old barrel was still on the receiver, I decided to take the flash suppressor off. My barrel wrench has three differently-sized openings at one end to accommodate different flash suppressors. If your barrel was factory-assembled, the flash suppressor may be attached very firmly; in this case you'll either need to invest in a barrel block and vise route or just take it to a shop and beg them not to charge you $50 to unscrew a stuck piece of metal. I lucked out and was able to get the flash suppressor off the pistol barrel with only moderate wrenching.
http://230grain.com/images/articles/ar15brl/tn_arbblflashhideroff.jpg (http://230grain.com/images/articles/ar15brl/arbblflashhideroff.jpg)
Now you get to use the other end of the barrel wrench. There is a large slot in one end with three pins protruding around its perimeter. These pins engage the barrel nut as follows:
http://230grain.com/images/articles/ar15brl/tn_arbblwrenchfit.jpg (http://230grain.com/images/articles/ar15brl/arbblwrenchfit.jpg)
There is also a square hole in the middle of the barrel wrench that accepts a socket wrench for more leverage. You will almost always need the help.
http://230grain.com/images/articles/ar15brl/tn_arbblwrench.jpg (http://230grain.com/images/articles/ar15brl/arbblwrench.jpg)
Again, the barrel nut may be extremely tight depending on where it came from, who assembled it, and how dirty it is. Mine took a lot of wrenching. I ended up finding a lever of equal length to the socket wrench I was using with the barrel wrench and threading it through the upper receiver's carry handle (I guess it's good for something after all!). I knelt on one lever and pushed on the other. Nothing. Finally I grabbed one lever in each hand and braced the receiver with my foot. After some straining, grunting, and swearing, the barrel nut broke free. Once you've achieved similar results, unscrew the barrel nut all the way. The barrel itself should now come free from the front of the upper receiver; again, depending on how new or dirty the barrel is, it may take additional effort.
http://230grain.com/images/articles/ar15brl/tn_arbbloff.jpg (http://230grain.com/images/articles/ar15brl/arbbloff.jpg)
Once the barrel is off, take a look at the rear of the barrel nut and delta ring assembly. You will see a snap ring on the back, holding the delta ring and delta ring spring in place. Notice also how the gap in the snap ring lines up with the gaps in the spring and the delta ring, and also lines up with one of the notches on the barrel nut. This is, of course, where the gas tube goes through into the receiver.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubetunnel.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubetunnel.jpg)
Next, use your snap ring pliers to spread apart the snap ring and remove it. The delta ring spring and delta ring itself can now be removed. The barrel nut stays on the barrel unless you want to mess around with taking the front sight block off. In mil-spec units, doing so can be as painful as barrel removal.
http://230grain.com/images/articles/ar15brl/tn_arbblsnapringpliers.jpg (http://230grain.com/images/articles/ar15brl/arbblsnapringpliers.jpg)
http://230grain.com/images/articles/ar15brl/tn_arbbldeltaringoff.jpg (http://230grain.com/images/articles/ar15brl/arbbldeltaringoff.jpg)
Reinstall the delta ring, spring, and snap ring on the new barrel, then install the barrel on your receiver. You can see that there is a post on the barrel extension that fits into a corresponding notch in the receiver.
http://230grain.com/images/articles/ar15brl/tn_arbblreceivernotch.jpg (http://230grain.com/images/articles/ar15brl/arbblreceivernotch.jpg)
Now use the barrel wrench to tighten the barrel nut. There are probably specific figures out there for torque and such, but I just tighten it until two criteria are met: The barrel nut is tight, and one of the notches lines up with the gas tube hole in the receiver. After the barrel nut is tight, insert the tip of the snap-ring pliers or a similar implement into the gap in the snap ring and rotate it so the gap lines up with the gas tube hole in the receiver. Similarly, make sure the delta ring and spring line up. Now you can check the barrel nut alignment to see if you need to do more wrenching.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeholerear.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeholerear.jpg)
http://230grain.com/images/articles/ar15brl/tn_arbblgastubeholefront.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubeholefront.jpg)
Fit your gas tube back in place. This is usually done by putting the back of the tube through the delta ring assembly and into the receiver while holding the gas tube so that the bend is perpendicular to the floor (if the receiver is sitting upright), then rotating the gas tube so that the lower front section lines up with the hole in the handguard cap and front sight base. You can also insert the gas tube from inside the receiver, so do whatever is easiest. Now is usually the point at which you realize that the barrel nut and delta ring assembly only looked like they were lined up, when in reality you still need to do some fine-tuning with the barrel wrench. Regardless, be careful not to bend or dent the gas tube.
http://230grain.com/images/articles/ar15brl/tn_arbblgastubebackin.jpg (http://230grain.com/images/articles/ar15brl/arbblgastubebackin.jpg)
Fit the gas tube forward into the front sight base. Depending again how dirty your barrel is, you may need to clean the gas tube cavity in the front sight base. Ensure the gas tube pin hole is lined up. Find the gas tube pin that you made sure not to lose and gently tap it back into place. Note: there is a school of thought that says any time you remove a roll pin it should be replaced with a new one. I generally subscribe to this theory, but in this case I was building a beater rifle whose purpose in life is to be tortured. If the pin breaks after a hundred rounds, I'll order a new one and chalk it up to science.
http://230grain.com/images/articles/ar15brl/tn_arbblgaspinbackin.jpg (http://230grain.com/images/articles/ar15brl/arbblgaspinbackin.jpg)
Put the handguards back on. Insert the charging handle and bolt, checking for fit. An unusually tight fit toward the front part of the bolt's travel may indicate a bent or misaligned gas tube. Go back and correct as necessary. Install the upper on the lower and perform a parts check: Make sure you don't have any spare parts lying around (aside from the barrel you just removed). Now perform a function check: Cycle the bolt a few times, making sure it seats fully when released. Lock the bolt open, then hit the bolt release. Dry fire. Cycle the bolt again. Put the safety on and pull the trigger; hopefully nothing happens. Put the weapon back on fire. Dry fire, but hold the trigger to the rear while cycling the action once more. Release the trigger and listen for the click of the hammer releasing from the disconnector. Pull the trigger again. If everything works to your satisfaction, test-fire with live ammo. If you have blanks and a blank adapter, you may want to try those first.
Here's the final product: an A2 AR with an M4 barrel and a CAR stock. I'm going to use it mostly for training purposes, either with blanks or empty for simple weapon handling drills. First, though, let's take it to the range to learn just how shot out that $25 Las Vegas barrel is.
http://230grain.com/images/articles/ar15brl/tn_arbblfinished.jpg (http://230grain.com/images/articles/ar15brl/arbblfinished.jpg)
[Test Fire]
I took the beater out to the range for a quick test drive. With it went a 20-round Colt mag loaded up with 62-grain Wolf (in the older lacquered cases). It ran beautifully: not a single function issue.
Zeroing was done on a standard M4 target at 25 yards. First group:
http://230grain.com/images/articles/ar15brl/tn_P2050237.jpg (http://230grain.com/images/articles/ar15brl/P2050237.jpg)
It was a little on the large size and obviously not centered, but not too bad. A few clicks down and to the left produced the second group:
http://230grain.com/images/articles/ar15brl/tn_P2050238.jpg (http://230grain.com/images/articles/ar15brl/P2050238.jpg)
Moving one click back up and paying more attention to the sights:
http://230grain.com/images/articles/ar15brl/tn_P2050239.jpg (http://230grain.com/images/articles/ar15brl/P2050239.jpg)
There we go: all three rounds in the center of the zero target. The barrel can't be all that bad as far as wear goes. Now let's roll a target out to the 100 yard line and fire off the rest of the mag.
http://230grain.com/images/articles/ar15brl/tn_P2050241.jpg (http://230grain.com/images/articles/ar15brl/P2050241.jpg)
Again, not bad. All shots fell within the 5-ring at a hundred yards with iron sights, Wolf ammo, and my crappy eyesight, all with a barrel that was taken out of service at a machine gun rental range.
I predict that the first thing to give me trouble on this rifle will be the non-staked bolt carrier key. If I were going to dump more money into this build, that'd probably be the first thing I'd fix.