Thinking the 80% route, Questions
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Old 03-30-2011, 08:42 PM   #1
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Default Thinking the 80% route, Questions

I am thinking very seriously about trying the 80% route and have a couple of questions.

First of which is why would I need to Anodize the lower? Is it a corrosion issue? I think the silver look is kind of cool.

Anybody on here done this? I am looking at Colfax's jig over the others (CNC and TacticalMachine) for one simple reason.

Colfax Tactical

80% AR-15 Lower Receiver Jig

CNCGUNSMITHING - www.cncguns.com - AR15 80% Tooling / Drill Jig

It has the drilling pattern on the top plate for use in a home drill press setting, like the TacticalMachine one does too, but it completely encases the lower forging allowing it to be clamped level without the mag well protruding out the bottom.

Any other's out there I have not found yet?

I know it is not that much of a price break doing this, if any. So save the "Cost/Work" argument. It is just pretty freakin cool to be able to legally do this and have one I said I finished.
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Old 03-30-2011, 08:51 PM   #2
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I'll comment on all of this thoroughly when I get home from work.
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Old 03-30-2011, 08:53 PM   #3
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Or you could step up to Supporting Member and have access to a thread where Spitty detailed the entire process from start to finish. Lots of pictures and lots of information.

JD
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Old 03-30-2011, 09:00 PM   #4
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Wait for Spitty's reply tonight. Me as a retired mechanical engineer, and he as a machinist; I'd take his suggestions/experiences as gospel.

IMHO, drill press machining an AR lower is a waste of good aluminum.
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Old 03-30-2011, 09:26 PM   #5
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Originally Posted by Dillinger View Post
Or you could step up to Supporting Member and have access to a thread where Spitty detailed the entire process from start to finish. Lots of pictures and lots of information.

JD
Alright so I bit the bullet and coughed up 15 bucks, Now what?
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Old 03-30-2011, 09:31 PM   #6
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Spitty's AR Build
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Old 03-30-2011, 10:35 PM   #7
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I found it in the "Bunker" VERY impressive build. I am not looking into doing a raw forge build, not yet. A very good friend of mine has all the milling tools one could EVER need. But I am planning A true 80% build. I am getting the jig from Colfax. I will also be getting the 80% forging form either Colfax or Tactical Machining. All of the little holes for the pivot detents, grip and bolt catch and what not are already drilled as well as the Mag Well.

I just read through Spitty's build and I love the detail he went into and It WILL be a great help. One thing I noticed at the very end is the conversation he had with the RO of the range.

Fact is, and I have researched this alot, is that the Lower you made IS NOT REQUIRED TO HAVE A SE#!!

BATF regs basically say that you can make this and DO NOT HAVE TO HAVE A SE# as long as you are not making it to sell or transfer. A BIG debate is going as to If they can ever be "Transferred" but consensus is that Even if you only shoot it once, you can sell or "Transfer" it. And still don't need a SE#. As Long as the firearm does not fall into NFA guidelines it is perfectly legal to make, own and shoot, PEROID!!

So Tell the RO to read the BATF regs, or better yet find them, print them out and show him. The 80% blanks or forgings are legal to sell BECAUSE they don't have the FCG wells milled out. BATF sees them as "Paper Weights" and not working firearms.


The Jig from Colfax has all the little drill points for the FCG well and trigger hole. I might use my home drill press which is a pretty damned good Delta press or I might get my friend a 1.75L of Old Forester and get his help and machine.
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Old 03-30-2011, 11:44 PM   #8
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Alright so I bit the bullet and coughed up 15 bucks, Now what?
The Bunker is FULL of all sorts of good stuff, not just Spitty's impressive feats of machining.

Give aways.

Fund raisers. (We raised almost $1,000 for returning troops to say Thank You when they home)

Hijinx.

Entertainment galore.

Thanks for signing up - I think you will get your monies worth.

JD

EDIT: Did I mention the Promotive Discount plan.

Last edited by Dillinger; 03-30-2011 at 11:51 PM. Reason: Added a thought
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Old 03-30-2011, 11:52 PM   #9
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Here are my thoughts on all these guide plates.

1. They are all overpriced. I know everyone's got to make a profit but I bet they have less then 1/2 of the asking price in materials and machine time.

2. I think they could, key word here is could, work but I think it would be a frustrating task. I'm following what was outlined here, CNCGUNSMITHING - www.cncguns.com - AR15 80% Lower Receiver Tutorial
These guys are using a mill. TacticalMachining.com • View topic - VaderSpade which changes the game.
I have an issue with using aluminum as a guide to drill aluminum. The drill is going to want to walk and since the guide is the same material you can basically eat your guide as you drill and you're hole will end up being off slightly which can cause problems later. You could use a 1/8" transfer punch to help this if you have one.
Once you have drilled the 37 1/8" holes and you step up to 3/8" here is where I see trouble starting. A 1/8" drill will bend, walk, cant, whatever else you want to call it but basically you end up with a hole that isn't 100% straight. You can remedy this by going extremely slow but since you have little way to gauge how fast you're feeding the drill into the material other then feeling it's hard to maintain consistancy. Now that you're starting with your 3/8" drills and drilling between the 1/8" holes the fun starts. If one of the 1/8" holes is off slightly or one side is thinner then the other the drill is going to walk itself towards the thinner material and once it does you will have one heck of a time getting it to cut straight again and the number of times you're repeating this process only increases the chances of this happening. It may not be an issue at all but it was the first thing that popped into my head.

3. When it comes to final milling out of the pocket you're basically turning your drill press into a router which again, could work but it could get very frustrating and result in a lot of chatter(bit jumps around) which will give you rough edges and also increases your chances of breaking a bit, gouging your guide or lower. Oh yeah, no where on his parts list does he mention an end mill but I see him repeatedly using one in the pictures and in his description. You simply cannot complete this job with an endmil, you actually need an extended end mil.

4. His methods of set up and measurement while they are possible and would probably create a functioning lower reciever are extremely crude and inaccurate. I see a great chance of the lower not being straight and level in the press which may or may not affect function later, but it could.


One thing that wasn't mentioned was the lower edge of the selecter stops. They have to be milled slightly to allow the safety selecter to rotate properly and it doesn't mention anywhere that they have milled this or how you should/could mill this.

Now that I'm done with my negative thoughts here are my possive ones. Yes, it is possible for you to complete a lower using only a drill press and their guide plates but you'll have $225-250 dollars tied up in a poorly machined (no offense, I'm not an expert machinist by any stretch I'm just trying to be honest) lower which doesn't count your time and whatever bits/tools you'll need to buy that you may not already have. If you do complete the lower you'll have the satisfaction of doing it yourself, just like I did and you'll have a lower that the ATF doesn't need to know about as you mentioned in your earlier post. If you want to take on the project then have fun and I'll be happy to help.
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Old 03-31-2011, 12:09 AM   #10
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Quote:
Originally Posted by spittinfire View Post
Here are my thoughts on all these guide plates.

1. They are all overpriced. I know everyone's got to make a profit but I bet they have less then 1/2 of the asking price in materials and machine time.

Agreed, Like I said It's not about saving money

2. I think they could, key word here is could, work but I think it would be a frustrating task. I'm following what was outlined here, CNCGUNSMITHING - www.cncguns.com - AR15 80% Lower Receiver Tutorial
These guys are using a mill. TacticalMachining.com • View topic - VaderSpade which changes the game

I have an issue with using aluminum as a guide to drill aluminum. The drill is going to want to walk and since the guide is the same material you can basically eat your guide as you drill and you're hole will end up being off slightly which can cause problems later. You could use a 1/8" transfer punch to help this if you have one.

If you follow the tutorial, the author of one of them, strongly outlines the use of the top plate as a guide for the SHANK of the bit, not the cutting part. This makes some sense to me but I am not a machinest.


Once you have drilled the 37 1/8" holes and you step up to 3/8" here is where I see trouble starting. A 1/8" drill will bend, walk, cant, whatever else you want to call it but basically you end up with a hole that isn't 100% straight. You can remedy this by going extremely slow but since you have little way to gauge how fast you're feeding the drill into the material other then feeling it's hard to maintain consistancy. Now that you're starting with your 3/8" drills and drilling between the 1/8" holes the fun starts. If one of the 1/8" holes is off slightly or one side is thinner then the other the drill is going to walk itself towards the thinner material and once it does you will have one heck of a time getting it to cut straight again and the number of times you're repeating this process only increases the chances of this happening. It may not be an issue at all but it was the first thing that popped into my head.

3. When it comes to final milling out of the pocket you're basically turning your drill press into a router which again, could work but it could get very frustrating and result in a lot of chatter(bit jumps around) which will give you rough edges and also increases your chances of breaking a bit, gouging your guide or lower. Oh yeah, no where on his parts list does he mention an end mill but I see him repeatedly using one in the pictures and in his description. You simply cannot complete this job with an endmil, you actually need an extended end mil.

4. His methods of set up and measurement while they are possible and would probably create a functioning lower reciever are extremely crude and inaccurate. I see a great chance of the lower not being straight and level in the press which may or may not affect function later, but it could.


One thing that wasn't mentioned was the lower edge of the selecter stops. They have to be milled slightly to allow the safety selecter to rotate properly and it doesn't mention anywhere that they have milled this or how you should/could mill this.

The part you are forgetting is that the forging I will use is literally an 80% forging. Meaning EVERYTHING is complete except the FCG well and the Trigger and selector pin holes. The Detent/spring hole for the selector is drilled, just not the selector hole, part of the ATF loophole. All of the other holes and outside final milling is done, that is why they cost more than the blank you worked on.

Now that I'm done with my negative thoughts here are my possive ones. Yes, it is possible for you to complete a lower using only a drill press and their guide plates but you'll have $225-250 dollars tied up in a poorly machined (no offense, I'm not an expert machinist by any stretch I'm just trying to be honest) lower which doesn't count your time and whatever bits/tools you'll need to buy that you may not already have. If you do complete the lower you'll have the satisfaction of doing it yourself, just like I did and you'll have a lower that the ATF doesn't need to know about as you mentioned in your earlier post. If you want to take on the project then have fun and I'll be happy to help.
I will keep you all posted.
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