Ar15 Lower: Jumping In

[Rick Leslie]

Look into homemade etching set-ups. Cheap and easy. I'll try to get some links posted later.

 

[n3480h]

Tom I would check with them as many places will not touch a home made gun part. By working on a completed lower they are doing work to a firearm and can get unwanted attention from our favorite government agency.

I suppose that's right, and I appreciate the caution. Seems there are laws being written at a furious pace to turn most of us into criminals sooner or later, lol. I hear it's now a federal offense to collect any amount of rain water. Far be it from me to break any laws.

Hadn't thought about etching, but that's a possibility if done before ceracoat and the etch is deep enough. Are there regulations dictating exact placement of serial numbers or "identification", and the depth of those markings? I have another idea that I want to experiment with before doing it on an almost finished lower.

 

[n3480h]

Just watched a video where a billet receiver was electro-etched. Very simple process, and any image that can be digitally produced can be etched into metal. Requires simple tools, a basic battery charger, vinegar and salt. As luck would have it, my wonderful daughter-in-law custom cuts vinyl. The vinyl is used as a mask. No acids or other problematic chemicals are required. This will be the solution to identifying the receiver. In fact, I may add an appropriate graphic to celebrate this freedom.

Big thanks to Rick for making me curious enough to learn about this.

Tom

 

[weaselfire]

Keep the BATFE engraving depth requirements in mind. A lot of jewelry and trophy shops aren't used to etching or engraving deep enough. DIY etching has a similar problem.

Jeff

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[n3480h]

Well, we'll see how this goes. This is the artwork for the passenger side of the magwell. Produced in CorelDraw.

 

[Rick Leslie]

DIY etching is easy and cheap. https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=diy etching metal

I was going to engrave my tube with the mini CNC, but with no 4th axis, it won't turn out too well. I'm going the etching route.

Doh!! Double post. Sorry.

I've etched aluminum just experimenting. It works really well. And goes deep enough to satisfy BATF requirements. Glad you may be able to use this.

 

[n3480h]

Thanks Rick. This is the video I found:

He definitely goes deeper than .003". I was surprised at how good the resolution was, but it appears that undercutting could happen if one went too far. Really like that this can be done with common household things which most of us already have on hand. Another video shows how to fill engraving with paint (for those so inclined), but the guy leaves far more paint in the engraving than is needed. A better method might be to spray lightly with a rattle can then wipe off the excess to leave a thin coat in the bottom.

Tom

 

[Rick Leslie]

I did mine with a scrap cell phone charger, Q-tips and salt water. Worked great. I plan to step up to a real battery charger (more depth and faster) and I've made some better stylii for more uniform coverage.

It seems the undercutting is related to the quality of the stencils being used. Cheap stencils burn off and ruin the detail.

Glad you can use this method.

 

[n3480h]

I don't have a good history with taps, but tapping the buffer tube threads went very well. I squared and clamped the lower onto the mini mill and loaded up a 3/8" center in the spindle. Zeroed inside the bore with a wiggler and lubed the tap with Tapmatic oil. The tap from Brownell's is the 6 flute style, so backing up to clear chips didn't take a lot of effort. The buffer tube fits nicely (and it's straight!) and stops just short of the center pin on the buffer retainer as it should. I cleaned up the edge of the bore for the buffer retainer pin to make certain the pin still fit and functioned as it should. Happy happy. In the end, this op was not as difficult as I had thought it might be. Really couldn't ask for a nicer thread.

 

[unioncreek]

The depth requirement only affects licensed manufactures. Home builder don't even need to put any ID'ing marks on a lower. If i can find the copy of a letter a friend recieved from ATF I will post it.

Bob

Keep the BATFE engraving depth requirements in mind. A lot of jewelry and trophy shops aren't used to etching or engraving deep enough. DIY etching has a similar problem.

Jeff

Sent from my XT1254 using Tapatalk