m4 going under the knife

[300sniper]

there has been a couple things i wanted to do to my m4 now that that fed assault weapon ban has sunset. the m4 was previously a post ban by federal standards. being that my m4 is already registered as a california assault weapon, i can now add some of the evil features that the fed wouldn't allow before.

a collapsible stock was a must. i went with a rock river arms 6 position stock.

now for some gunsmithing. i knew i needed a flash hider. i wanted to stay with the m4 look so i wanted to go with an a2 flash hider. since my barrel was a non threaded m4 profile i decided to cut it down to about 15" and thread it to 1/2-28. this will give about a 16-1/4" length with the flash hider.





since i still can not have a sbr in california i needed to permanently attach the flash hider. i chose to braze it on. i used a fast flowing brazing filler that melted at 1200*. the filler flows like solder and was sucked into the threaded connection. this should satisfy the law. after brazing it and seeing how much heat is actually involved i decided that i will not use this method again.



next i bead blasted the flux and other mess off the barrel and preheated it to about 150*. after it heated up for about 10 minutes i sprayed it with norells moly resign in flat black. it then went back in the oven at 300* for an hour.







next was the upper receiver. i cleaned it up real quick in the blast cabinet and heated it to 150*. i sprayed it with the moly resign and baked for an hour at 300*.





now it was time for assembly. this is where i messed up. i used a leather tig welding glove to protect the upper receiver in the vice. this was not good enough as the picatinny rail cut through it like a razor. the picatinny rail is messed up enough that i am going to buy another upper receiver. i went ahead and assembled it anyways for now.





what i learned from this project:
like i said earlier, i am not going to use heat to permanently attach the next flash hider. instead i am going to use a blind pin and a small tig spot weld to close the hole. i will then finish with a file to hide the weld.

also, i am now going to get a set of vice jaws for the receiver.

[Azzy2000]

Nice work as usual.

Too bad about the pic rail. I use a Brownell's plastic reciever vice and it works very well.

[300sniper]

Originally Posted by Azzy2000

Nice work as usual.

Too bad about the pic rail. I use a Brownell's plastic reciever vice and it works very well.

yea, that's what i get for not using the right tool for the job.

[troxy18]

http://img.photobucket.com/albums/v6...rebarrel05.jpg

Might be a noob question but I have only worked with Issued M-16's, shouldnt there be a gas tube along the top of the barrel? Or did you remove it for the baking and all that?

[300sniper]

Originally Posted by troxy18

http://img.photobucket.com/albums/v6...rebarrel05.jpg

Might be a noob question but I have only worked with Issued M-16's, shouldnt there be a gas tube along the top of the barrel? Or did you remove it for the baking and all that?

you are correct. the gas tube has to come out to remove the barrel from the upper receiver. it goes through the the notches in the barrel nut.

[aloharover]

Nice


While I understand the desire to have a weapon that looks like an M-4 I have never really understood why civilians would want the M-203 notch in the barrel.
I could be wrong, but I don't remember the M4 having a reduced diameter under the hand guard.
I would think that a full lenth heavy barrel would be better, strength, accuracy, heat dissipation, etc.

[300sniper]

Originally Posted by aloharover

Nice


While I understand the desire to have a weapon that looks like an M-4 I have never really understood why civilians would want the M-203 notch in the barrel.
I could be wrong, but I don't remember the M4 having a reduced diameter under the hand guard.
I would think that a full lenth heavy barrel would be better, strength, accuracy, heat dissipation, etc.

almost every m4 profile barrel i have seen had the reduced diameter under the hand guard. i think i have only seen one that didn't and it was an off brand manufacture.

as far as the m203 notch, it just looks cool

i have 2 other barrels i am going to play with. i think i will make my other m4 barrel 14-1/2" and permanently attach a phantom flash hider. i have a strait contour barrel that i think i will leave 16" but thread the end and leave the flash hider non-permanently mounted.

[surpip]

O/T do you know where i can get some 203 hand guards, i have a 203 in 37mm, and i would like to mount it to one of my Ar's but i cant find guards for it anywhere

[flecker]

Hey 300Sniper... really nice job man.

Do you do extra on the side? I have a postban Bushmaster shorty carbine that I would like to have threaded. Either that or I get off my cheap ass and order a different upper.

Think about... pm me or just throw a cost out there if your interested.

[300sniper]

Originally Posted by flecker

Hey 300Sniper... really nice job man.

Do you do extra on the side? I have a postban Bushmaster shorty carbine that I would like to have threaded. Either that or I get off my cheap ass and order a different upper.

Think about... pm me or just throw a cost out there if your interested.

let me mess with my other barrels first to get comfortable doing it before i do any one elses. i still need to get more tooling for my lathe. i kind of winged it on this project.

[Azzy2000]

Originally Posted by 300sniper

almost every m4 profile barrel i have seen had the reduced diameter under the hand guard. i think i have only seen one that didn't and it was an off brand manufacture.

I'm using a Colt military socom M4 barrel on my SBR and it is full dia. under the guards. C MP marked with 1:7 twist , F marked front site base.

[wentz912]

not to like totally hijack your thread 300sniper, but how many of you guys here, the few that i assume are the "gun guys" of the board, are current previous service eh?

[N_Rod]

Nice job on the barrel! Have you thought about silver soldering the next one? It wont take nearly as much heat and is very strong. Most of your manufacturers use silver solder. From bolt handles, vent ribs, to attaching barrels together for double barrels. Just a thought.

[flecker]

Originally Posted by 300sniper

let me mess with my other barrels first to get comfortable doing it before i do any one elses. i still need to get more tooling for my lathe. i kind of winged it on this project.

Well if that was your first time doing anything like that then I am really impressed!!!

Seriously, that's fairly advanced smithing in my book... and it turned out awesome.

[rockmup]

Originally Posted by N_Rod

Nice job on the barrel! Have you thought about silver soldering the next one? It wont take nearly as much heat and is very strong. Most of your manufacturers use silver solder. From bolt handles, vent ribs, to attaching barrels together for double barrels. Just a thought.

My thoughts too. Silver Solder is a great way to go. Nice work

[300sniper]

Originally Posted by N_Rod

Nice job on the barrel! Have you thought about silver soldering the next one? It wont take nearly as much heat and is very strong. Most of your manufacturers use silver solder. From bolt handles, vent ribs, to attaching barrels together for double barrels. Just a thought.

silver solder with a melting temperature of over 1100* is the recommended method. when i did some research i found that solder stops at 850* and it goes into the brazing area above that. atf requires at least a 1100* melting temperature to make a flash hider part of the barrel. i can't find the paper work on it but i used radnor "safety silv 56" high silver content brazing filler.

[300sniper]

Originally Posted by flecker

Well if that was your first time doing anything like that then I am really impressed!!!

Seriously, that's fairly advanced smithing in my book... and it turned out awesome.

that was my first "real" project on the lathe that i actually had to use callipers and a dial indicator. it was also my first time threading with the lathe. i have only messed around with it making shift knobs and other un-precision parts so i was pretty proud of how the threading turned out.

[f0cker]

Damn I really like that gun. Want to donate it to me?

[300sniper]

Originally Posted by Azzy2000

I'm using a Colt military socom M4 barrel on my SBR and it is full dia. under the guards. C MP marked with 1:7 twist , F marked front site base.

does that have a flat spot in the barrel under the hand guards? something that looks like it would be used for wrench to fit over?

[300sniper]

one more thing i learned last night. some times it is good to read the instructions before you attempt a project. i was reading in an old military manual on the m16a2 about replacing barrels and found out that you are supposed to hold the barrel in the vice, not the receiver. i still would have messed something up with out a holding fixture but now i know the proper way.

time to see when the next big reno gun show is.

[Bill4rest]

ANymore infor on the finish you used?

[300sniper]

Originally Posted by Bill4rest

ANymore infor on the finish you used?

http://www.molyresin.com/molyresin_about.asp

i used it on my upper and lower intakes, valve cover and timing cover on my 22re and it turned out nice also:



and the gears and pulleys on a lathe i restored:

[usmcdoc14]

If you need more practice let me know as I will send you stuff to thread
I want a 16" heavy barreled flat top upper threaded for a flash hider but I can get a non-threaded one for cheap.

[300sniper]

Originally Posted by usmcdoc14

If you need more practice let me know as I will send you stuff to thread
I want a 16" heavy barreled flat top upper threaded for a flash hider but I can get a non-threaded one for cheap.

like i told flecker, once i am confident with threading my own barrels, then i could probably work something out. give me a couple weeks to get the proper tooling and we'll see what happens.

[Azzy2000]

Originally Posted by 300sniper

does that have a flat spot in the barrel under the hand guards? something that looks like it would be used for wrench to fit over?

Yes. It looks like it was made for a wrench or attachment point for a launcher. Otherwise it is full diameter ,and not necked down.