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Link Posted: 4/26/2015 5:48:12 PM EST
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Originally Posted By LeonC:
Show of hands, who's broken a tap doing this?
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Not me, but if you did, then stop buying those cheap-ass Chinese taps and learn the correct way to use a tap with tapping fluid/cutting oil.
Link Posted: 4/26/2015 9:01:23 PM EST
[Last Edit: 4/26/2015 9:04:18 PM EST by lysanderxiii]
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Originally Posted By JoshAston:


You do realize that the barrel, barrel nut, takedown pin, pivot pin, hammer pin, trigger pin, hammer, trigger, hammer spring, trigger spring, endplate, castle nut, pistol grip screw, takedown pin detent, pivot pin detent, takedown pin detent spring, pivot pin detent spring, safety, safety detent, safety detent spring, ejection port door, ejection port door rod, ejection port door spring, forward assist, forward assist spring, forward assist roll pin, magazine release, magazine release spring, bolt catch, bolt catch plunger, and bolt catch spring are all steel parts against aluminum right?
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Originally Posted By JoshAston:
Originally Posted By freeport56:
[font=Times New Roman]What about the Electrolysis between the two metals? Will the steel dissolve the aluminum ?[/font=Times New Roman]


You do realize that the barrel, barrel nut, takedown pin, pivot pin, hammer pin, trigger pin, hammer, trigger, hammer spring, trigger spring, endplate, castle nut, pistol grip screw, takedown pin detent, pivot pin detent, takedown pin detent spring, pivot pin detent spring, safety, safety detent, safety detent spring, ejection port door, ejection port door rod, ejection port door spring, forward assist, forward assist spring, forward assist roll pin, magazine release, magazine release spring, bolt catch, bolt catch plunger, and bolt catch spring are all steel parts against aluminum right?

The bold portion is not quite true.

You really should Alodine the bare aluminum and put some epoxy primer (MIL-PRF-23377) on the set screw and install with the primer wet to return the assembly to (almost) the original level of corrosion resistance.

The original design has all aluminum surfaces hard coat anodized. Hard anodizing prevents actual contact between the aluminum and the steel, as the anodized surface is actually an anodic layer of non-conductive aluminum oxide. Since the anodized layer is non-conductive, there is no electrical connection between the steel and aluminum and therefore no galvanic corrosion. Further, the aluminum oxide layer is extremely corrosion resistant by itself.

Theoretically, removing the anodizing and leaving bare aluminum will restore the electrical bond between the steel and aluminum, but in order for there to be galvanic corrosion you will need an electrolyte. I doubt most of us will have our rifle sitting in a wet environment for days at a time, but that is why this is not approved by the military.

(Installing the set screw with wet primer on it makes an electrical insulative barrier, and chromate conversion coating, aka Alodine, is a coating that forms a strong passive oxide layer on bare aluminum, but does not create an insulating barrier, it is used often as it is a simple paint-on application.)


Link Posted: 6/14/2015 11:22:07 AM EST
Would synthetic grease like Mobile 1 prevent that bi-metallic problem?
Link Posted: 6/14/2015 11:32:33 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MikeE23666:
Would synthetic grease like Mobile 1 prevent that bi-metallic problem?
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If it does not conduct electricity.

A paint is generally better, as once it dries, it will not migrate or evaporate, like oils or greases.
Link Posted: 7/14/2015 5:37:27 PM EST
[Last Edit: 7/14/2015 5:52:01 PM EST by Plumber576]
BOOM! confetti.



Didn't have time to do them all but wanted to get one done so my beater 5.45 AR was the first victim. Went well except I forgot to buy/find a small enough hex key so I had to use a small screw driver.

I look forward to doing the rest.
Link Posted: 7/14/2015 8:17:18 PM EST
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Originally Posted By wjbaker1:
Great idea...but do you know how hard it was to find a 4-40 set screw? Nobody in 3 towns had them, I tried every hardware and auto parts store including ACE, Home Depot, Lowe's, and NAPA.

I finally found some stainless 4-40 set screws, but I had to buy a pack of 100.

So, since I have extras, if anyone needs some, contact me. My email is through Yahoo.

Bill.
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4-40 set screws are very common I the r/c hobby. Find a good hobby store and I'm sure you'll find them.
Link Posted: 7/14/2015 11:28:10 PM EST
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Originally Posted By jarhead13:


4-40 set screws are very common I the r/c hobby. Find a good hobby store and I'm sure you'll find them.
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Originally Posted By jarhead13:
Originally Posted By wjbaker1:
Great idea...but do you know how hard it was to find a 4-40 set screw? Nobody in 3 towns had them, I tried every hardware and auto parts store including ACE, Home Depot, Lowe's, and NAPA.

I finally found some stainless 4-40 set screws, but I had to buy a pack of 100.

So, since I have extras, if anyone needs some, contact me. My email is through Yahoo.

Bill.


4-40 set screws are very common I the r/c hobby. Find a good hobby store and I'm sure you'll find them.


I'm lucky enough to live near a Fastenal store. I bought a pack of 100. I now have a kit I'll take with me when I visit buddies and they can do their guns in return for a beer or a meal. I'm sure I'll come out on top!
Link Posted: 7/15/2015 5:23:08 PM EST
Glad I found this. Great mod.

Posted Via AR15.Com Mobile
Link Posted: 10/29/2015 10:11:15 PM EST
bump to prevent archive
Link Posted: 12/2/2015 8:21:40 PM EST
Freaking great idea, I am going to do this with all my lowers. I have Spartan Glock mag lower that came from the factory like this.
Link Posted: 12/2/2015 9:04:31 PM EST
[Last Edit: 12/2/2015 9:05:00 PM EST by PFran42]
I've seen this posted before but for those of you with no access to a store that sells 4-40 x 1/8' socket screws, you can buy a kit for under $6 on Amazon.



Link Posted: 2/8/2016 8:42:07 PM EST
Have a general question regarding the set screw itself...

  • If using the typical hardened steel set screw, what would be a good dab of grease on the threads to prevent galling or other issues removing the screw down the line?
  • If using a stainless steel set screw, what would be a good grease for the same reason?

I found the hardened type at a R/C hobby shop and have it installed in my rifle at the moment but I was thinking of checking the local Ace hardware or Fastenal for a stainless screw. I bought a tube of anti-sieze, supposedly good for aluminum heads at the local auto parts store, but I noticed it has graphite in it. Seem to recall graphite being on the "do not use this grease if..." list. Think this anti-sieze would be fine considering how little of the grease would actually be used? If I can't find the stainless screw and keep the one that's currently installed, will something like the Mobil 1 grease do the trick?

Thanks in advance...
Link Posted: 2/9/2016 8:20:01 AM EST
I've done several of my lowers, and think it's a great/easy mod.

The only thing that worries me is that I don't have any experience besides these mods using a tap this small, so I'm starting to get worried and wonder just how many lowers a 4-40 tap can do before it accumulates enough micro-fractures to snap off in the hole.

Just sayin'.
Link Posted: 2/9/2016 10:08:59 AM EST
Gonna have to do this on my next build. In my only AR that spring is bent up because of me fighting it but it still works the same
Link Posted: 2/9/2016 10:52:35 AM EST
[Last Edit: 2/9/2016 10:53:08 AM EST by WHITE_WOLFE]
The stuff you gun nuts worry about amazes me.


ETA: I have done this to all my ARs.
Link Posted: 2/9/2016 12:19:49 PM EST
Did this. Best mod ever. Very easy to swap between collapsible and A2 stocks now.
Link Posted: 6/14/2016 6:17:18 AM EST
bumping for posterity
Link Posted: 6/14/2016 6:59:20 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By kaos:
I've done several of my lowers, and think it's a great/easy mod.

The only thing that worries me is that I don't have any experience besides these mods using a tap this small, so I'm starting to get worried and wonder just how many lowers a 4-40 tap can do before it accumulates enough micro-fractures to snap off in the hole.

Just sayin'.
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I did 6 with a tap I had until it did this.
Link Posted: 6/14/2016 10:35:53 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By harleyms:
I found the set screws at Fastenal.....had to buy a pack of 100, so after a buddy and I did all ours I now have about 90 left. Anyone need some? lol
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I'll take 10! Just throw in an envelope. I'll pp you a buck.
Link Posted: 8/27/2016 6:29:26 AM EST
Bump for those who haven't seen this.

I have made a little kit that a take with me to houses of friends I know have AR's and do it for them (or teach them how to do it). I have 80-some remaining little screws and I plan to get them all in lowers.
Link Posted: 10/27/2016 9:42:12 AM EST
Whew, I've read through all 11 pages! us-kiwi posted a link for set screws, and after reading the concerns about steel/stainless/aluminum, I spotted these: Plastic Nonmarring Flat Point Set Screws

Described as "Made of nylon, these screws offer chemical resistance at an economical price. They also have a flat point that minimizes surface damage. All have a Class 2A thread fit. Temperature range is –40° to 185° F. Color is off-white." they come in a 100-pack for $5.46.

Opinions?


Link Posted: 10/28/2016 9:01:01 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Gator84:
Whew, I've read through all 11 pages! us-kiwi posted a link for set screws, and after reading the concerns about steel/stainless/aluminum, I spotted these: Plastic Nonmarring Flat Point Set Screws

Described as "Made of nylon, these screws offer chemical resistance at an economical price. They also have a flat point that minimizes surface damage. All have a Class 2A thread fit. Temperature range is –40° to 185° F. Color is off-white." they come in a 100-pack for $5.46.

Opinions?


View Quote
Some plastics get chalky and brittle as they outgas.
I have zero knowledge of this nylon product, and it's been a while since I had first hand experience with plastics in general that I had long enough to worry about, but it'd be something I thought about if I was to use some of these.

I'm not an expert, and I don't want anyone thinking I'm trying to be one.
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