A Tale of Two Crush Washers, or Two Crush Washers One Barrel, and other AR oddities
- Thread starter cmshoot
- Start date
Vet your AR builder, and have someone knowledgeable look over any AR that’s built outside of the factory. Depending on what factory that is, might be a good idea to have them look over those, too!
LEO came in, had an AR he bought from a guy that built it for him in his garage shop in Powder Springs. He was purchasing it for duty use, and he works in a jurisdiction where it wouldn’t surprise me if he ends up using it.
I have no issues with garage shops……..I build great AR’s in my basement shop. I do have issues with folks selling AR’s that are built improperly, and out of cheap parts, when they’re intended for serious use.
Guy paid just under $700 for it. Anderson forged lower, Anderson 16” barrel, unknown billet upper receiver with no FA, cheap Chinesium rail with no anti-rotation provision, USGI-style stock and pistol grip, Magpul polymer sights……..
He brought the rifle to me because he almost ran out of right windage (rightage?) getting it on paper. A quick visual check showed that the barrel was not even close to being in the center of the rail. It was way to the left, which would explain all the right windage to get on paper. I explained that it could be a crooked rail, or it could be the extension on the front of the upper receiver where the barrel mounts. There are other possibilities, but those are the most common.
I disassembled the upper. The barrel is nitrided, and the barrel wasn’t dimpled for the gas block screws. A nitride finish is very smooth and hard. There is no way that the knurled gas block screws can bite into a nitrided surface. Eventually, under use, that gas block would start walking towards the muzzle, and it would cease to cycle. I dimpled the barrel for the gas block set screws, and provided new screws.
I lapped the face of the upper receiver, and reassembled the upper. Still crooked.
I grabbed a long Picatinny clamp, and installed it across the top, bridging the upper receiver and the rail. This corrected the issue, so the problem is that the rail is ill-made and crooked.
He picked out a new 15” rail; an Aero MLOK S-One. This solved one problem, and created a second. The S-One rail has extensions on both sides that overlap the sides of the upper receiver, providing anti-rotation. This rail, like many others, will only work with an upper that has milspec external dimensions, which few billet uppers do.
We kicked around a few options, and ended up replacing the unknown billet upper with a forged Aero upper. I disassembled his upper again, and rebuilt it into the new Aero upper with no issues.
Went to drop the upper into the lower, noticed that the castle nut wasn’t staked, and the receiver extension (buffer tube) was not straight up and down. I partially pulled the upper apart to correct these issues. When I removed the pistol grip, I found that instead of using a selector lever detent for the safety, Bubba had used a takedown pin detent.
Torqued the castle nut to spec, and staked it twice. Reinstalled the pistol grip and selector lever, using the correct detent.
For the same amount of money, I could have built him a properly assembled AR, or he could have bought a S&W or Ruger AR. While neither are my favorites, they’re assembled a helluva lot better than Bubba did this one.
LEO came in, had an AR he bought from a guy that built it for him in his garage shop in Powder Springs. He was purchasing it for duty use, and he works in a jurisdiction where it wouldn’t surprise me if he ends up using it.
I have no issues with garage shops……..I build great AR’s in my basement shop. I do have issues with folks selling AR’s that are built improperly, and out of cheap parts, when they’re intended for serious use.
Guy paid just under $700 for it. Anderson forged lower, Anderson 16” barrel, unknown billet upper receiver with no FA, cheap Chinesium rail with no anti-rotation provision, USGI-style stock and pistol grip, Magpul polymer sights……..
He brought the rifle to me because he almost ran out of right windage (rightage?) getting it on paper. A quick visual check showed that the barrel was not even close to being in the center of the rail. It was way to the left, which would explain all the right windage to get on paper. I explained that it could be a crooked rail, or it could be the extension on the front of the upper receiver where the barrel mounts. There are other possibilities, but those are the most common.
I disassembled the upper. The barrel is nitrided, and the barrel wasn’t dimpled for the gas block screws. A nitride finish is very smooth and hard. There is no way that the knurled gas block screws can bite into a nitrided surface. Eventually, under use, that gas block would start walking towards the muzzle, and it would cease to cycle. I dimpled the barrel for the gas block set screws, and provided new screws.
I lapped the face of the upper receiver, and reassembled the upper. Still crooked.
I grabbed a long Picatinny clamp, and installed it across the top, bridging the upper receiver and the rail. This corrected the issue, so the problem is that the rail is ill-made and crooked.
He picked out a new 15” rail; an Aero MLOK S-One. This solved one problem, and created a second. The S-One rail has extensions on both sides that overlap the sides of the upper receiver, providing anti-rotation. This rail, like many others, will only work with an upper that has milspec external dimensions, which few billet uppers do.
We kicked around a few options, and ended up replacing the unknown billet upper with a forged Aero upper. I disassembled his upper again, and rebuilt it into the new Aero upper with no issues.
Went to drop the upper into the lower, noticed that the castle nut wasn’t staked, and the receiver extension (buffer tube) was not straight up and down. I partially pulled the upper apart to correct these issues. When I removed the pistol grip, I found that instead of using a selector lever detent for the safety, Bubba had used a takedown pin detent.
Torqued the castle nut to spec, and staked it twice. Reinstalled the pistol grip and selector lever, using the correct detent.
For the same amount of money, I could have built him a properly assembled AR, or he could have bought a S&W or Ruger AR. While neither are my favorites, they’re assembled a helluva lot better than Bubba did this one.
You got an opinion on a Ruger MPR? Also, probably going to have to meet up with you soon. My buddy has an AR that he assembled with decent parts, but now it can’t run an entire mag without one jam. Normally happens in the first 10 rounds.
They’re normally OK for the money. Assembly is subpar, and parts aren’t the best. For instance, the other day I had my hands on one where the gas key wasn’t properly installed. Barely staked, with YFS fasteners. I was able to easily break both bolts loose on the gas key; one at 35 inch/lbs and the other at 40 inch/lbs.
well looks like I’ll drop off my rifle and my buddies if you got time. I’m going to be out of town for annual training, but I’ll drop them off probably the first week of august if that’s ok.
You left out the superglue.
Adult legos
