DIY Upper- How Hard

[michaelmew]

If the diifficulty of building a lower from parts, on a scale of 1 to 10, is say a 5 (some of the pins are a PITA and if you aren't careful your tools will scratch up your receiver); what would the rating be for building an entire upper just from parts?

I'm having second thoughts about taking this on with no upper experience, although I am 100% confident on lowers. Particularly getting the spacing between the bolt and barrel correct if I don't buy them together.

[pinzgauer]

at the risk of sounding like a smartass, if you have to ask you are not ready.

Minimum prerequisites:

• Proper clamps/blocks for holding the upper. There are a couple of good ones... I use a DPMS claw based on local smith input, but the Brownell's one LR1995 suggested a while back would be my new pick. (But the claw works find)
  
• Good Armorer's wrench (for barrel nut and flash hider). Again, DPMS actually makes decent one. There may be better available, but of all the ones I've handled / used I like theirs. Shame the rifles are not as nice!
  
• Torque wrench (and knowledge to use it, how to hold, etc) Make sure it fit's your armorer's wrench!
  
• Good understanding of how the uppers go together. Barrel nut to receiver relationship, gas tube, etc. Lot's of good how-to's with photo's out there. Look at your own rifle
  
• one of 3-4 different anti-seize or grease choices. Entire villages have been destroyed in the flame wars on which anti-seize to use. Just pick one of the known good choices.
• angle gauge or some other method to index the flashhider properly. You can eyeball it, but getting it right is not hard or expensive.

For Grendel's normally the bolt comes with the barrel and will be properly headspaced. Some will tell you to check headspace regardless, but that's not set by you, it's the mfg when they install the extension on the barrel. So buy as a pair from a quality mfg and it will be set properly.

Some will tell you that it's OK to homebuild for plinkers, but to get an accurate rifle you have to have it build with secret sauce. That has not been my experience.... the AR design itself does not allow for much fitting. IE: Barrel & component quality has a much larger impact.

And the few items in the upper you can fit can be done yourself with inexpensive tools if you decide it's important. (Like making sure the upper receiver to barrel interface is square)

Unless you are buying a premium barrel, optics, upper receiver, etc, the secret sauce fitting stuff won't make as big of a difference as the barrel upgrade will. And a trigger upgrade follows the barrel in priority.

Again, you'll know when it's time. If you have not already, start with assembling a lower or full kit. It's actually a bit more involved in terms of steps, but none of them are quite as "major" as installing the barrel is.

Back to your "factor"- I'd say 6 or 7 max assuming top notch components & proper tools. It actually takes less time than assembling a lower, just less fiddly stuff. I found that top tier components are not really any more expensive. And I'd avoid Delton, generic, DPMS, etc. Colt, Daniel Defense, etc are readily available. Though I don't like their rifles as much, Rock River loose parts were quite good and easy to get.

Torquing the barrel sounds very hard, but the way the AR works you are just torquing to a minimum value (quite low, actually), then tightening till the next gas tube index lines up cleanly. Bit of a PITA to hold the armorer's wrench in against the delta ring spring, but not hard. Overtorquing decreases accuracy most have found.

Flash hider is not hard, just make sure your compression washer is facing the right direction. (Peel washers are more of a pain). Hard to screw up, and cheap to fix if you do. Just order extra compression washers of good quality! Also, make sure your armorer wrench fit's your flashhider flats. The proper way to install is to use two hands and avoid torquing the barrel like would occur if you just used a wrench. Like using a two handed lug nut wrench.

This all assumes a non-pinned gas block/front sight base. If you want to use the traditional FSB you'll need another jig to do it right. (Though some drill them without the jig/block) Some barrel mfg's will provide a drilled barrel & loose pinned FSB for you.

[kamrr4437]

I believe there are several videos on youtube on how to assemble and upper. And as far as scratching up your lower receiver just use lots of electrician tape on the tools your using and plastic or rubber hammer. But tape! tape! tape! and you will have you a flawless lower receiver. Lots of good info in the above post as well.

[LRRPF52]

Pinzgauer,

Excellent response. Installing AR15 barrels is a breeze when you have the right tools. I can't think of too many other rifle platforms that allow the user to do barrel installation or part replacement like with the AR, which is one of the reasons why it's such a successful design.

You brought up the issue of barrel-to-upper receiver squareness. I understand how this works on bolt guns, and met a smith at a local range last year that does it on AR15 & AR10 builds. He said he made his own tools for checking and cutting the upper receiver extension face true, truing the threads, truing the barrel extension threads, truing the barrel extension flange on the rear and front, and truing the bolt carrier raceway. He also trued the barrel nut inner flange, and trued the lugs to the barrel extension. He was shooting sub-half MOA groups with his Grendel, so I can't say that he was doing anything wrong.

I just want to get into making sure my upper receiver extension face is square to the barrel extension flange, and that those are square to the bore axis. Aside from accuracy, I think these are important for reliability and bolt life, as imbalanced loads on the lugs will shear them quickly when the barrel is not square with the upper.

What are your suggestions for purchasing or making a tool that checks for upper receiver extension face squareness? I've been thinking about a tool that fits inside the upper raceway from the front, and can turn on the face of the extension. If you wanted to get really picky, you would true the inner flange of the barrel nut, so it will apply evenly-distributed compressive force against the barrel extension flange and the receiver extension face.

LRRPF52

[Slaxer07]

Pinzgauer,

Excellent response. Installing AR15 barrels is a breeze when you have the right tools. I can't think of too many other rifle platforms that allow the user to do barrel installation or part replacement like with the AR, which is one of the reasons why it's such a successful design.

You brought up the issue of barrel-to-upper receiver squareness. I understand how this works on bolt guns, and met a smith at a local range last year that does it on AR15 & AR10 builds. He said he made his own tools for checking and cutting the upper receiver extension face true, truing the threads, truing the barrel extension threads, truing the barrel extension flange on the rear and front, and truing the bolt carrier raceway. He also trued the barrel nut inner flange, and trued the lugs to the barrel extension. He was shooting sub-half MOA groups with his Grendel, so I can't say that he was doing anything wrong.

I just want to get into making sure my upper receiver extension face is square to the barrel extension flange, and that those are square to the bore axis. Aside from accuracy, I think these are important for reliability and bolt life, as imbalanced loads on the lugs will shear them quickly when the barrel is not square with the upper.

What are your suggestions for purchasing or making a tool that checks for upper receiver extension face squareness? I've been thinking about a tool that fits inside the upper raceway from the front, and can turn on the face of the extension. If you wanted to get really picky, you would true the inner flange of the barrel nut, so it will apply evenly-distributed compressive force against the barrel extension flange and the receiver extension face.

LRRPF52

AR Receiver lapping tool Brownell's has one also.

[michaelmew]

Actually, while building a friend's lower, we figured out how to get around taping everything and found a really easy way to install the pins. Use a pair of vice grips and hold the pin in the grips so it is in-line, not perpendicular to the ends. That is confusing, but I don't know how else to describe. Think of it like this: C- .If the "C" was the clamp and the "-" was the pin. Leave a small amount of the pin hanging out. Use the pliers to push the pin part way into the hole. Release and re-clamp further down on the pin and repeat until it is totally installed. Use a minimal amount of oil to make it go smoother. This method means you dont need to hammer anything and risk marring your lower. If you do scratch it, just remember, you are building a tool and if you use it, it will get scratches.

[pinzgauer]

I just want to get into making sure my upper receiver extension face is square to the barrel extension flange, and that those are square to the bore axis. Aside from accuracy, I think these are important for reliability and bolt life, as imbalanced loads on the lugs will shear them quickly when the barrel is not square with the upper.

What are your suggestions for purchasing or making a tool that checks for upper receiver extension face squareness? I've been thinking about a tool that fits inside the upper raceway from the front, and can turn on the face of the extension. If you wanted to get really picky, you would true the inner flange of the barrel nut, so it will apply evenly-distributed compressive force against the barrel extension flange and the receiver extension face.

I'll defer to others with more experience on this, as I've not done this on my builds. From talking with folks and reading, the jury is out how much it really helps if you are using in spec components. If you somehow end up with out of spec components it can make a difference.

In general, the theme is that it cannot hurt, and if you are grossly out of spec it will help.

Others indicate that the face of an in-spec upper receiver (what you would hone) deforms as needed when torqued, so it's an unneccesary step which just removes your hardened surface, etc. Which somewhat makes sense. There are also debates around whether the barrel extension can even cant enough if in-spec to to allow unequal bolt lug loading. So who knows.

The Brownells tool (or similar) appears to be what nearly everyone uses, and it's not expensive. But if you are going to go to that trouble, it does seem like you'd want to true up the flange as well just to be sure.

As for a gauge, the trick would be a block that goes in the receiver, with a rotating arm that holds a dial indicator on the face. you'd have to make sure the tool itself did not have play in it. Or the poor man's equiv would be to mount your barrel into the receiver under slight pressure, but not via barrel nut. Then look for gap with feeler gauge, etc.

If I ever do a build with a premium barrel I'll probably make the attempt. But for now I can safely say that unsquare receivers have not been a limiting factor in my builds! (Watch me break a bolt lug tomorrow from jinxing myself)

I've seen some discussion around trying to check trueness of an existing mounted barrel, usually involving longbed mills.

[LRRPF52]

Slaxer07,

AR-Stoner have earned themselves a well-deserved slot on my s**t list. I ordered a Nickel Boron BCG from them, and the plating has already peeled off the bolt in numerous places after a few test-fires. In contrast, it looks nothing like the Nickel Boron that FailZero uses, and I have had nothing but great performance with several of theirs.

Does anyone know where AR-Stoner is headquartered, or where their parts are made? The "Nickel Boron" BCG I got from them looks like really cheap chrome-plating, with a rough textured finish.

LRRPF52

[z06man]

LRRPF52, here's the Brownell's version.

http://www.brownells.com/.aspx/pid=20220/Product/AR_15_M16_UPPER_RECEIVER_LAPPING_TOOL

From what I have read, their barrels are made by ER Shaw. I don't know about any of their other parts.

[glane5910]

Slaxer07,

AR-Stoner have earned themselves a well-deserved slot on my s**t list. I ordered a Nickel Boron BCG from them, and the plating has already peeled off the bolt in numerous places after a few test-fires. In contrast, it looks nothing like the Nickel Boron that FailZero uses, and I have had nothing but great performance with several of theirs.

Does anyone know where AR-Stoner is headquartered, or where their parts are made? The "Nickel Boron" BCG I got from them looks like really cheap chrome-plating, with a rough textured finish.

LRRPF52

IIRC, AR-Stoner is just a name that Midway uses to sell that line of parts.

[TheOTHERmaninblack]

at the risk of sounding like a smartass, if you have to ask you are not ready.

Minimum prerequisites:

• Proper clamps/blocks for holding the upper. There are a couple of good ones... I use a DPMS claw based on local smith input, but the Brownell's one LR1995 suggested a while back would be my new pick. (But the claw works find)
  
• Good Armorer's wrench (for barrel nut and flash hider). Again, DPMS actually makes decent one. There may be better available, but of all the ones I've handled / used I like theirs. Shame the rifles are not as nice!
  
• Torque wrench (and knowledge to use it, how to hold, etc) Make sure it fit's your armorer's wrench!
  
• Good understanding of how the uppers go together. Barrel nut to receiver relationship, gas tube, etc. Lot's of good how-to's with photo's out there. Look at your own rifle
  
• one of 3-4 different anti-seize or grease choices. Entire villages have been destroyed in the flame wars on which anti-seize to use. Just pick one of the known good choices.
• angle gauge or some other method to index the flashhider properly. You can eyeball it, but getting it right is not hard or expensive.

For Grendel's normally the bolt comes with the barrel and will be properly headspaced. Some will tell you to check headspace regardless, but that's not set by you, it's the mfg when they install the extension on the barrel. So buy as a pair from a quality mfg and it will be set properly.

Some will tell you that it's OK to homebuild for plinkers, but to get an accurate rifle you have to have it build with secret sauce. That has not been my experience.... the AR design itself does not allow for much fitting. IE: Barrel & component quality has a much larger impact.

And the few items in the upper you can fit can be done yourself with inexpensive tools if you decide it's important. (Like making sure the upper receiver to barrel interface is square)

Unless you are buying a premium barrel, optics, upper receiver, etc, the secret sauce fitting stuff won't make as big of a difference as the barrel upgrade will. And a trigger upgrade follows the barrel in priority.

Again, you'll know when it's time. If you have not already, start with assembling a lower or full kit. It's actually a bit more involved in terms of steps, but none of them are quite as "major" as installing the barrel is.

Back to your "factor"- I'd say 6 or 7 max assuming top notch components & proper tools. It actually takes less time than assembling a lower, just less fiddly stuff. I found that top tier components are not really any more expensive. And I'd avoid Delton, generic, DPMS, etc. Colt, Daniel Defense, etc are readily available. Though I don't like their rifles as much, Rock River loose parts were quite good and easy to get.

Torquing the barrel sounds very hard, but the way the AR works you are just torquing to a minimum value (quite low, actually), then tightening till the next gas tube index lines up cleanly. Bit of a PITA to hold the armorer's wrench in against the delta ring spring, but not hard. Overtorquing decreases accuracy most have found.

Flash hider is not hard, just make sure your compression washer is facing the right direction. (Peel washers are more of a pain). Hard to screw up, and cheap to fix if you do. Just order extra compression washers of good quality! Also, make sure your armorer wrench fit's your flashhider flats. The proper way to install is to use two hands and avoid torquing the barrel like would occur if you just used a wrench. Like using a two handed lug nut wrench.

This all assumes a non-pinned gas block/front sight base. If you want to use the traditional FSB you'll need another jig to do it right. (Though some drill them without the jig/block) Some barrel mfg's will provide a drilled barrel & loose pinned FSB for you.

Only one point of contention with this post. Aside from extra long wait times for product shipping, I have yet to hear anything bad about Delton, and the rifle kit I purchased from them (though with a pre-assembled upper) is seriously pretty and is shooting near MOA through a cheap Bushnell red dot. Somewhere down the road that thing is going to be wearing a 6.5 barrel and I won't worry a bit about it.

As for assembling an upper, except for the angst of the torquing and the need for the block, I'd call it a 4, as the only really fiddly bit is the gas block alignment and pinning.