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Page Armory » M-16
Posted: 1/29/2015 12:21:42 AM EDT
I posted this over in the gunsmithing forum but have not received much feed back so i figured i would post here as well.

I have late 1970s Olympic Arms M16 Lower. Unfortunately the top deck is out of spec, it is too high and all mil-spec uppers make contact with the top deck. I have to force the upper into place and literally hammer the rear take down pin into position.

I would like to remove a small amount of the top deck, probably around 1/100 of a inch.

What would be the best method of doing this?

My first thought was to use a sanding block/stone to remove the small amount of material plus keep a square edge, i believe a file might remove to much material and leave a uneven surface. For reference im an Engineer and have access to a machine shop and plenty of tools. I understand the standard response when dealing with a machine gun is "send it to a gunsmith" and i thank everyone for their concern but i would really prefer to do the work myself. I understand the risks and i still want to proceed.

This is what i am trying to accomplish and i think will resolve the issue im having. The picture is of an identical lower (same make and model) which the owner had a gunsmith remove some of the top deck, rear radius and material in between the front face between the take down pin lugs.


Overview of the gap between the upper and lower receiver. This is how close they get without applying force to close the gap and alight the rear pin holes.


Close up of the gap. Notice how the pin holes do not come close to lining up.


You can see where the upper and lower are making contact, especially near the front of the mag well near the front take down pin. This wear was visible when i bought the rifle.


Contact area between the front take down pin lugs. Does not seem to be rubbing on the BCM upper though.


On the left side you can see wear marks on the upper from the lower. Its a new upper btw.


I def feel the top deck is out of spec and needs to be milled/sanded down. Obviously this is a touchy issue when it comes to transferable machine guns. But since this is not a colt i dont see how performing gun smithing that will bring the lower into spec a negative thing. Sure it will remove the original finish on the upper deck but IMO thats a small price to pay to have any mil spec upper fit the lower properly.

The other option would be to sand the lower deck of the upper receiver. This will avoid damaging the lower but i loose the convenience of being able to put any upper on it. I will be limited to uppers which i have specifically sanded/milled to fit the lower.

All thoughts and suggestions are welcomed.

Thanks

~S
Link Posted: 1/29/2015 12:35:53 AM EDT
[#1]
Contact M60 Joe
Link Posted: 1/29/2015 12:54:35 AM EDT
[#2]
If you take off too much and you want to sell the problem cheaply to someone else, shoot me a PM.  

If you want to take that in, I would mill the buffer radius lightly, like .003 each pass.

I would also get a lower receiver blueprint, measure, measure, then measure, and measure again to get an idea of how much material goes where.

You can take material off, but it's very very very difficult to put back on. I have a access to a laser welder, but unfortunately, I can't help anyone else with this tool.
Link Posted: 1/29/2015 7:30:50 AM EDT
[#3]
Might as well cut your losses and sell it cheap... To me

But really I would send it to a gunsmith to do the work, don't want to make a mistake in a 15k piece of aluminum
Link Posted: 1/29/2015 7:56:51 AM EDT
[#4]
Did you sleep at a Holiday Inn last night?

Break out the mill and go for it. What's the worst that could happen?
Link Posted: 1/29/2015 8:25:21 AM EDT
[#5]
Having experience in removing material is one thing, being an engineer is another.  Wish you luck. Call M60 Joe.
No worries.

.
Link Posted: 1/29/2015 8:57:39 AM EDT
[#6]
As the other guys have said- send it to M60joe.  He's not just "a gunsmith", but the industry-wide "go-to" guy for this type of repair.  He has the fixtures to do this repair quickly and properly and will have your receiver back to you in no time.

Having said that, if you really want to do the work yourself- go for it.  It ain't rocket science.  I've done it to a non-MG SGW receiver and I'm no engineer.  Just take your time and keep things square.  Whether you use a file, a sanding block, or a Bridgeport, remove material until the upper and lower go together like they should, then stop.

If you frack it up completely, THEN send it to M60joe.  You'll still wind up with a correct receiver, but it'll be more expensive.  

PS- after you're done fixing it, send it to U.S. Anodizing for a proper coat of hard anodize and you'll have a lower that works, looks good, and will last for your lifetime and your children's.

Good luck!!
Link Posted: 1/29/2015 9:33:55 AM EDT
[#7]
Please take no offense to this, but being an engineer does not make you a machinist, and that cold be an expensive fix after removing too much material. If you do not have plenty of hands on experience with the machines, I personally wouldn't go that route. If you plan on doing it by hand, the key would be to stay as square and flat as possible and measure more than you think you will need to. As mentioned before, get a MIL spec print and measure everything before starting. I have done hand fitting of parts in the aerospace field for a while now, it can be done just take your time if you are dead set on doing it yourself.
Link Posted: 1/29/2015 10:42:16 AM EDT
[#8]
What happens if try to install the rear pin first?  What does the front hole look like?
Link Posted: 1/29/2015 11:35:27 AM EDT
[#9]
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Quoted:
Please take no offense to this, but being an engineer does not make you a machinist, and that cold be an expensive fix after removing too much material. If you do not have plenty of hands on experience with the machines, I personally wouldn't go that route. If you plan on doing it by hand, the key would be to stay as square and flat as possible and measure more than you think you will need to. As mentioned before, get a MIL spec print and measure everything before starting. I have done hand fitting of parts in the aerospace field for a while now, it can be done just take your time if you are dead set on doing it yourself.
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Quoted:
Please take no offense to this, but being an engineer does not make you a machinist, and that cold be an expensive fix after removing too much material. If you do not have plenty of hands on experience with the machines, I personally wouldn't go that route. If you plan on doing it by hand, the key would be to stay as square and flat as possible and measure more than you think you will need to. As mentioned before, get a MIL spec print and measure everything before starting. I have done hand fitting of parts in the aerospace field for a while now, it can be done just take your time if you are dead set on doing it yourself.


No offense taken. Was not trying to indicate i was a master machinist, im certainly not. But just wanted to people to understand i have a technical background and am not just some Neckbeard trying to file down his firearm with an empty beer can.

I certainly feel im capable of doing the work. I would do it slow and use a pair of calipers to keep track of the material removed and check fitment with the upper throughout the process.

But even if i do a great job im still left with a unanodized surface. The best i could do would be apply Aluminum Black, it would protect from corrosion but not abrasion, especially compared to a hard coat anodize.

Plus if i kind of want to fill down the nub at the front of the mag well and the ridge in the trigger guard, which i assume is the weld that was never properly removed in the factory back in the day when QA/QC standards were not the highest.

Quoted:
Might as well cut your losses and sell it cheap... To me

But really I would send it to a gunsmith to do the work, don't want to make a mistake in a 15k piece of aluminum


Just for fun i weighed the stripped lower, its 8.2 oz. Comes out to around $1,800 per oz...more expensive per oz than gold haha
Link Posted: 1/29/2015 11:52:51 AM EDT
[#10]
dude, take a $100 upper and cut to fit.

Don't fuck up a $16,000 lower

Txl
Link Posted: 1/29/2015 9:54:37 PM EDT
[#11]
My lower is the same , but just send it out. No need to ruin a good m16 rr. Kinda like saying I have a gal bladder that needs to be removed,  ill do it my self I have gutted several deer and im good with hand tools. May be ok, ok but caught a nasty infection, started cutting but cut a artery and Im bleeding to death.
Link Posted: 1/29/2015 9:58:23 PM EDT
[#12]
This can happen If a mill gets away from you!

Link Posted: 1/29/2015 10:23:52 PM EDT
[#13]
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Quoted:
This can happen If a mill gets away from you!

<a href="http://s745.photobucket.com/user/sergio762/media/IMG_0877-1_zpsg8bacuxv.jpg.html" target="_blank">http://i745.photobucket.com/albums/xx96/sergio762/IMG_0877-1_zpsg8bacuxv.jpg</a>
View Quote

Hmm yeah that would be a bad day for sure with a RR

As much as i would live to do it myself I'm leaning towards having it professionally done. I would like to have the welds sanded down and a few other spots worked on and with not being able to anodize it seems pointless for me to do the work and then have a bunch of bare metal showing or at best the awkward color difference between hard coat and liquid rub on anodizing.

Prob just take it to the range one last time, shoot it some then toss it in the mail and wait the month plus till it returns
Link Posted: 1/29/2015 11:00:14 PM EDT
[#14]
Send it to M60Joe.  Do it for the children.
Link Posted: 1/29/2015 11:10:24 PM EDT
[#15]
Discussion ForumsJump to Quoted PostQuote History
Quoted:

Hmm yeah that would be a bad day for sure with a RR

As much as i would live to do it myself I'm leaning towards having it professionally done. I would like to have the welds sanded down and a few other spots worked on and with not being able to anodize it seems pointless for me to do the work and then have a bunch of bare metal showing or at best the awkward color difference between hard coat and liquid rub on anodizing.

Prob just take it to the range one last time, shoot it some then toss it in the mail and wait the month plus till it returns
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Quoted:
Quoted:
This can happen If a mill gets away from you!

<a href="http://s745.photobucket.com/user/sergio762/media/IMG_0877-1_zpsg8bacuxv.jpg.html" target="_blank">http://i745.photobucket.com/albums/xx96/sergio762/IMG_0877-1_zpsg8bacuxv.jpg</a>

Hmm yeah that would be a bad day for sure with a RR

As much as i would live to do it myself I'm leaning towards having it professionally done. I would like to have the welds sanded down and a few other spots worked on and with not being able to anodize it seems pointless for me to do the work and then have a bunch of bare metal showing or at best the awkward color difference between hard coat and liquid rub on anodizing.

Prob just take it to the range one last time, shoot it some then toss it in the mail and wait the month plus till it returns


For the love of God send it to a professional. Be sure to send it certified mail.
Link Posted: 1/30/2015 12:14:36 AM EDT
[#16]
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Quoted:

For the love of God send it to a professional. Be sure to send it certified mail.
View Quote


Registered Mail insured?

And without the anodizing, the bare aluminum surface is about as hard as a cheese burger...
Link Posted: 1/30/2015 10:05:00 AM EDT
[#17]
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Quoted:


Registered Mail insured?

And without the anodizing, the bare aluminum surface is about as hard as a cheese burger...
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Quoted:
Quoted:

For the love of God send it to a professional. Be sure to send it certified mail.


Registered Mail insured?

And without the anodizing, the bare aluminum surface is about as hard as a cheese burger...


Registered mail can be insured for up to $25,000 and seems like a pretty save way to ship.

mmmm cheeseburger But yes i agree it needs to have a hard coat anodize so it looks like i will be sending it out soon.
Link Posted: 1/30/2015 11:25:28 AM EDT
[#18]
@Spartikis:
Just follow the blueprint I did and send it to M60Joe. He can literally have it out a day or 2 later. Mine was incredibly fast - I think the day he looked at it was the day he milled it. I am sure he has set up a jig to address all of these kinds of issues. I am extremely satisfied (as you know from the thread I made). Additionally, Victor@ USAnodizing did an amazing job and that was also well done. I wanted to get a shooter grade brought into spec and give it a fresh coat. It's tip top now.... I couldn't be happier with the results, and I do not look back on it wondering if I could have done the same thing. I simply know that mine is in spec, accepts all uppers, and functions flawlessly. And while it doesn't have a pony roll mark, I didn't pay for one.

http://www.ar15.com/forums/t_6_23/434824_Frankford_Arsenal_Oly_conversion____my_experience_from_the_beginning_.html
Link Posted: 1/30/2015 11:41:00 AM EDT
[#19]
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Quoted:
dude, take a $100 upper and cut to fit.

Don't fuck up a $16,000 lower

Txl
View Quote



That's what I'd do.

Modify the least expensive part.   In this case, the upper.
Link Posted: 1/30/2015 1:14:40 PM EDT
[#20]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
@Spartikis:
Just follow the blueprint I did and send it to M60Joe. He can literally have it out a day or 2 later. Mine was incredibly fast - I think the day he looked at it was the day he milled it. I am sure he has set up a jig to address all of these kinds of issues. I am extremely satisfied (as you know from the thread I made). Additionally, Victor@ USAnodizing did an amazing job and that was also well done. I wanted to get a shooter grade brought into spec and give it a fresh coat. It's tip top now.... I couldn't be happier with the results, and I do not look back on it wondering if I could have done the same thing. I simply know that mine is in spec, accepts all uppers, and functions flawlessly. And while it doesn't have a pony roll mark, I didn't pay for one.

http://www.ar15.com/forums/t_6_23/434824_Frankford_Arsenal_Oly_conversion____my_experience_from_the_beginning_.html
View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Quoted:
@Spartikis:
Just follow the blueprint I did and send it to M60Joe. He can literally have it out a day or 2 later. Mine was incredibly fast - I think the day he looked at it was the day he milled it. I am sure he has set up a jig to address all of these kinds of issues. I am extremely satisfied (as you know from the thread I made). Additionally, Victor@ USAnodizing did an amazing job and that was also well done. I wanted to get a shooter grade brought into spec and give it a fresh coat. It's tip top now.... I couldn't be happier with the results, and I do not look back on it wondering if I could have done the same thing. I simply know that mine is in spec, accepts all uppers, and functions flawlessly. And while it doesn't have a pony roll mark, I didn't pay for one.

http://www.ar15.com/forums/t_6_23/434824_Frankford_Arsenal_Oly_conversion____my_experience_from_the_beginning_.html

Thats what im going to do. Working on getting the form 4 copied and typing up a letter for the repair work to send with it. Will ship via USPS registered mail fully insured. While its there i will have a few other issues i would like worked out like taking that nub off of the front of the mag well which i believe is excess welding and smooth down a few other areas that have sharp edges and scratches. Once is all down it will get reanodized. Mechanically it should be as good as a Colt but for $10,000+ less.

Quoted:
Quoted:
dude, take a $100 upper and cut to fit.

Don't fuck up a $16,000 lower

Txl



That's what I'd do.

Modify the least expensive part.   In this case, the upper.

the problem with modifiyng the upper is i would have to do it to every upper i own, which isnt a lot now but i might be interested in getting more now plus if i can find a decent deal on a used shrike i would love to pick one up so so i can say i have a belt fed

Also, once i go to sell it the first question people ask is if its in spec. And unlike the person who sold it to me i can say yes it is completely in spec and show them receipts of the work that was performed.
Link Posted: 1/31/2015 8:38:58 PM EDT
[#21]
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Quoted:
Contact M60 Joe
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THIS.

I sent mine to Joe and it's a 100% with any upper I use now.
Link Posted: 1/31/2015 9:12:32 PM EDT
[#22]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
dude, take a $100 upper and cut to fit.

Don't fuck up a $16,000 lower

Txl
View Quote




FOR THE LOVE OF GOD THIS, It is obvious that at one time it fit an upper........................DUH, CUT THE UPPER !!!!!!!!!!!!
Link Posted: 2/1/2015 11:34:46 AM EDT
[#23]
I'd go for the lower mod. No F-up = WIN.

M60joe = No F-up = WIN!
Page Armory » M-16
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