Required tools to install a barrel and align FSB?

[Crash]

I was recently thinking about changing the barrel on one of my rifles, and a friend of mine who is an armorer and deputy for the U.S. Marshal Service advised me not to do it. He's been to several armorers schools, including HK, Glock, and Colt's(Ken Elmore). He told me that Ken Elmore had advised during his class, that to properly install a barrel and align the front sight base, it required a thousand dollar tool. He advised all of his students not to mess with the barrel.

I figure Ken Elmore has forgotten more about AR's than I'll ever know so.... Is it really that difficult to properly align the front sight post?

[Robb Jensen]

Changing a barrel doesn't require removal of the front sight base (FSB). It only requires removal if you're going to a different barrel nut (aftermarket FF tube etc).

And the taper pins that are currently in it align it all by themselves if you're keeping factory the FSB and adding an aftermarket FF tube/rail.

[Crash]

I was looking at changing out the barrel assembly, without touching the FSB on the replacement. I understand that the barrels are indexed. Is it possible to misalign a correctly installed barrel assembly? Have you ever heard of this thousand dollar tool?

[Robb Jensen]

I was looking at changing out the barrel assembly, without touching the FSB on the replacement. I understand that the barrels are indexed. Is it possible to misalign a correctly installed barrel assembly? Have you ever heard of this thousand dollar tool?

No on the $1000 tool. The barrel aligns itself via the index pin on top of the barrel extension into the notch in the upper receiver. I do use a $15 gas tube alignment tool to get the barrel nut alignment straight with upper. I would caution you against changing your own barrel if you've never done it yourself. If your friend (the armorer) will be present then go ahead and do it, but from reading your posts, he may have never done it either which is odd for a Colt armorers course, I took the Bushmaster course at Blackwater and we did it.

I install, reinstall 2-3 bbls per week, so much that it's second nature. The reason I caution you against it is that you're dealing with something that can blow up in your face and injure or kill you (but probably won't even if you screwed it up). Or at the very least not work properly and/or break or ruin parts. It's not difficult, but does take a few tools to do it properly.

Ken Elmore was probably talking about the drilling fixture that drills the FSB and barrel at the same time during assembly on new barrels at the Colt factory. This isn't re-done in a barrel swap where the FSB isn't removed or is but reinstalled on the same barrel. If using any other gas block you do have to align it and there are methods that work pretty good. I use a 'slave' gas block (same brand I'll be installing) with the top cut off so that I can see the gas port in the block centered on the port in the barrel and then I dimple the barrel so that the set screws on the gas block cannot allow it to move when installed and I use Rocksett on the set screws. So that it won't move under the heat and 13.5K to 26K PSI that's pushed through the gas block.

[Crash]

Can you elaborate on what is so difficult? I don't mean to sound arrogant, but if I never change one, how do I learn? Perhaps I need to take an armorer's class, but Ken Elmore's won't teach me how to replace the barrel.

I've built two AR's and the only things that I have not done myself are the barrel and front sight base. I guess I am just wanting to understand how to completely assemble the rifle correctly.

Thanks for the input.

[Quib]

I have a few barrel changes under my belt, there is no science to it. To ensure the FSB and barrel indexing remain centered, have someone hold the FSB with pressure in the opposite direction as you torque the barrel nut.

[Hoplophile]

Can you elaborate on what is so difficult? I don't mean to sound arrogant, but if I never change one, how do I learn? Perhaps I need to take an armorer's class, but Ken Elmore's won't teach me how to replace the barrel.
I'm 99.999999999999999999999% sure that Ken will teach you how to change one in his class, or you could just grab a copy of the military armorers manual (the -23) which tellls how to do it. I don't know the context for Ken's comment on a thousand dollar tool was but something obviously got lost in translation. Either your friend didn't understand what Ken said, or he didn't understand your question or you didn't understand his answer.

My best guess is that Ken was talking about building a barrel into a barrel assembly, which requires several expensive tools and a lot of work. AR15barrels.com has a photo essay on the whole process if you're interested. But none of that means jack shit to guys like you and me because we don't buy barrels, we buy barrel assemblies that already have the barrel extensions installed and usually a front sight base installed. The only way we're likely to get a barrel assembly without a FSB installed is if it's a "match" type barrel like a Noveske that is mean to have a gas block installed with set screws.

Or maybe Ken was referring to some specialized thing like that KAC upper that requires a special $600 wrench for the barrel nut.

The most expensive tool needed when installing a normal barrel assembly in a normal upper receiver is a plain old torque wrench.

[Soulrack223]

I would venture he was referring to the installation of the barrel extension and the drilling of the pin holes for the front sight base. Getting those two items (FSB and Barrel Extension) in perfect alignment is what is crucial. Once that has been accomplished you can remove and re-install the FSB and it will still be in alignment with the barrel extension. I am no armourer, but I have done it to change handguards to float tubes and vice versa with no problems.

[Crash]

Can anyone elaborate on what problems Bushmaster was/is having with Front Sight Bases being misaligned from the factory? I thought it was an issue with over torqueing the barrel nut, but wouldn't the index pin prevent this from happening? Of course, that assumes that the FSB was installed correctly.

Hoplophile:
Absolutely something could have been lost in translation. That's why I attempted to make it as clear as possible that I was getting second hand information. My brother inlaw is the marshal, and he works serving warrants on a what they call a "high risk" team. He maintains their weapons. Its a secondary role so he really isn't in depth. I'm fairly certain this class was taught from that prespective. Not in depth work, but maintenance. They carry UMP45, MP5, Colt Commandos, Colt M4s, and Glocks, hence they've sent him to those schools. I beleive that they're taught to basically inspect and maintain, and if the repair requires something more extensive, they would send the rifle out for repair. That may explain why they were advised not to remove the barrels.

Where all of this is coming from is my project to build my own version of an AR10 Mark 11 clone. I was looking at purchasing one of BigBore's Pac Nor barrels and installing it myself. My brother-inlaw and I were talkig guns, and I told him about my project. That's when he cautioned me not to do it myself, but to send it out and have a proffesional armorer handle it. When I asked him why, he repeated what he understood from Ken Elmore. From a novice's point of view, this seems like a fairly simple process. Purchase the barrel, have bigbore install the gas block, and then I can easily fit the rifle onto my receiver and install the gas tube. Again, from a novice's point of view, this seems like child's play. But if that were true, why does everyone keep saying things like "I would caution you against changing your own barrel if you've never done it yourself."

I'm just trying to understand the pitfalls before jumping off. I really appreciate the input.

[Hoplophile]

why does everyone keep saying things like "I would caution you against changing your own barrel if you've never done it yourself."

Please define "everyone". You certainly won't hear that around places like this or ar15.com where a large percentage of the posters are far from being qualified as professional armorers yet they have installed barrels on uppers without any problems.

[Quib]

Please define "everyone". You certainly won't hear that around places like this or ar15.com where a large percentage of the posters are far from being qualified as professional armorers yet they have installed barrels on uppers without any problems.


My 15 year old son does a lot of his own maintenance and PM to his weapon! :) Including assisting with complete re-builds!

[C4IGrant]

The issue that BM was having was poor QC. It is very difficult to properly cut the holes for the taper pins and have them square up with the receiver. So that is most likely what Ken was talking about (would agree with him).

Pulling the FSB and re-installing it is pretty simple. They can SOMETIMES be off a little bit, but isn't hard to fix.



C4

[Treehopr]

Hey Crash,

I recently put together two uppers for the first time and the hardest part for me was getting the FSB taper pins out.

The first one actually came out fairly easily once I started hitting it hard enough but had enough difficulty with the second upper that I ended up cutting the FSB off with a Dremel.

I could've taken it to a professional but, like you, I wanted to see if I could do it myself :D

Good luck,

treehopr

[MASP7]

FYI- The Colt factory M16 armorer's school no longer teaches barrel removal/installation. (This was as of last summer- Elmore was not the instructor)
They discussed it like it was somewhere between black magic and splitting atoms. I just rolled my eyes and persevered...
They didn't even discuss removing the FSB.

[LukeMacGillie]

FYI- The Colt factory M16 armorer's school no longer teaches barrel removal/installation. (This was as of last summer- Elmore was not the instructor)
They discussed it like it was somewhere between black magic and splitting atoms. I just rolled my eyes and persevered...
They didn't even discuss removing the FSB.

Yep, I recerted in Sept of this year and barrel changes are no longer taught, not even a fancy slide show:(

The time that used to be spent on barrel changes is now used for an extra 5 iterations of tear down and rebuild of the rear sight. Has anyone ever had a rear sight go bad?

In 15 years of Armorering(11 as an additional duty/Table top and 4 full time) and ive never worked on a rear sight outside of the Colt course.

[MASP7]

The time that used to be spent on barrel changes is now used for an extra 5 iterations of tear down and rebuild of the rear sight.


Oh yeah... I can disassemble and set up an A2 rear sight in my sleep.
That'll come in handy...

The other thing that I most remember was the quality of the rifles.
They were so sloppy and worn out that they could nearly be disassembled by a strong shaking! This did help make for a fast disassembly/reassembly time though.

[Robb Jensen]

Yep, I recerted in Sept of this year and barrel changes are no longer taught, not even a fancy slide show:(

The time that used to be spent on barrel changes is now used for an extra 5 iterations of tear down and rebuild of the rear sight. Has anyone ever had a rear sight go bad?

In 15 years of Armorering(11 as an additional duty/Table top and 4 full time) and ive never worked on a rear sight outside of the Colt course.

Colts Attorneys probably rewrote the course for liability reasons. My thinking is because you almost can never F up a rifle just by putting a new bolt in it. (you won't be adding headspace just by adding a new bolt.) But you could much more easily F it up trying older much more worn barrels with less worn bolts etc. I guess they figure that if you can't headspace (and don't know how to change a barrel because they won't teach you) an upper you'll either replace the entire upper or return it to Colt.

LukeMacGillie,
Thanks for the info on the throat erosion gauge, I ordered one (you can't have too many tools! ;) )

At my armorers course (Bushmaster at Blackwater) we took the rear sights apart probably 8 times. I've only had to repair one since then. The flat spring under the aperatures went bad. Usually if I work on a A2 rear sights it's to install night sights or Ashley same plane aperatures.

[Crash]

I spoke with my brother inlaw again and he confirmed exactly what was said above. His class was taught by Ken, and when I read him the quote from MASP7's post, "They discussed it like it was somewhere between black magic and splitting atoms", he just laughed and said that was a pretty good description.

He also stated that what they were taking was the "M16 Armorer Course" and not their advanced course. He wasn't sure if the advanced course would cover it or not, but he doubted it. You still wouldn't have their mysterious thousand dollar tool to ensure the barrel was aligned properly.

For me, I think I'll plug ahead and purchase the barrel I want for my AR10. If it gets to be too scientific for me, I'll just come running here. ;)

Thanks for the help everyone.

[Hoplophile]

Amazing. I find it hard to beleive that anything covered by the -23 could be considered too difficult for "certified armorers" but I guess that's why I'm not a lawyer.

There's plenty of barrel assemblies listed on the SAW web site, I wonder how Ken feels about not being allowed to teach "armorers" how to install parts that he sells.

[AR15barrels]

I install, reinstall 2-3 bbls per week, so much that it's second nature.

Amatuer... ;)


It's not difficult, but does take a few tools to do it properly.

Here are some of my tools:

http://www.ar15barrels.com/tech/tools.jpg

I recommend the DPMS "claw" (T) and the DPMS multi tool (E) as a good start.
For barrel nut alignment, I use a #11 drill blank.
$2.39 from McMaster Carr.

[Robb Jensen]

I have most of those except for B, C, J & N

I ordered a DPMS version of C about a week ago, I'll buy J&B when I need to, who makes N ?

About time you start coming around here again! ;)