Building a AR15 with a 80% polymer lower.

[1911ly]

Very cool project buddy! Glad you could get the boy involved!

I was skeptical of the poly lowers, until I got one for my birthday last year! Built it on the cheap, since I still wasn't sure of it, but after I pinned an upper on it and shot it, all apprehension went away! I figured there would be a lot of flex/feedback under recoil, but it felt exactly as it should, only lighter! I wouldn't want to go into battle with it, but as a range toy/backup gun, (Mine is actually a backup for my backup!), I don't think you can go wrong!

Hi Phil! I was skeptical too but it was unwarranted. It's find. I built this one on the cheap too. I am amazed at how well it does. Like you said, I don't know if I want to go to battle with it but I'd re\ather have this then nothing!

 

[philbert001]

Hi Phil! I was skeptical too but it was unwarranted. It's find. I built this one on the cheap too. I am amazed at how well it does. Like you said, I don't know if I want to go to battle with it but I'd re\ather have this then nothing!

My thoughts exactly! Is the jig you got useable for machining an aluminum lower too? I don't see why it wouldn't be, but wasn't sure if it's fit to something proprietary to the lower you built. I think a polymer practice run for 80% lowers is a great idea! Glad it panned out for ya!

 

[1911ly]

I am not sure. I just ordered a Tactical Machining jig and receiver. I will compare them. This poly jig is plastic. It's probably good to center and to mark for cuts. They say that there are differences in the jig. We will see! Phil if you want the plastic jig you can have it if it will work for a template for you. I might make the TM jig a loaner tool when I get done!

 

[philbert001]

I am not sure. I just ordered a Tactical Machining jig and receiver. I will compare them. This poly jig is plastic. It's probably good to center and to mark for cuts. They say that there are differences in the jig. We will see! Phil if you want the plastic jig you can have it if it will work for a template for you. I might make the TM jig a loaner tool when I get done!

I appreciate it, but I don't think I'm quite ready for an 80% project yet! Not sure I trust me OR my drill press that much! I was just curious if you'd be able to use it for more than just the poly lower.

 

[wabash]

hmmmm....... did you engrave a custom serial number onto that thing?

 

[Dsgnr_81]

Nicely done!

 

[1911ly]

hmmmm....... did you engrave a custom serial number onto that thing?

It's not legally required(because it's for myself) but I will be putting something n this.

Nicely done!

Thanks!

I appreciate it, but I don't think I'm quite ready for an 80% project yet! Not sure I trust me OR my drill press that much! I was just curious if you'd be able to use it for more than just the poly lower.

I have seen some of your projects. It am sure you could do it!

 

[philbert001]

I have seen some of your projects. It am sure you could do it!

Thank you sir!

I'm financially and spatially limited for the time being. One of these days I'll have a bigger shop and more tooling. At that point, watch out, cause I'll be trying to do it all!

 

[1911ly]

When you are ready you are welcome to use my jigs/tools. NP. I found a new Tactical Machining Gen 2 jig on Armslist. I need to order the lower. Probably before the night is over. I'll be machine an aluminum one really soon. I hope to get the chance to weld up my Sten Mark III this weekend.

 

[philbert001]

When you are ready you are welcome to use my jigs/tools. NP. I found a new Tactical Machining Gen 2 jig on Armslist. I need to order the lower. Probably before the night is over. I'll be machine an aluminum one really soon. I hope to get the chance to weld up my Sten Mark III this weekend.

 

[yournamehere]

I got one of these exact lowers in a deal as a add on I didnt expect. Looks decent enough and it was still in the sealed box. I have 4 aluminum lowers on my bench at the moment and the best deals I have found on lowers is at
http://www.submoatarget.com/AR15-80-Lower-GS-80L.htm
They shipped the same day I ordered and they have the keyhole forge mark that I wanted since its a top tier supplier. $69 dollars and I was going to go with HLF or Tactical Machining but these are just as good and I have them in hand to verify it. I got my jig used from a guy at AR15 and I just am going to use the side plates to hold it. My DRO and the prints I have made the use of the top plates not needed. Ray-Vin had plans and cool do it yourself guides. You can actually make your own side plates for holding the lower from their prints as well.

I had to wait on an Enco order and had to send my Z axis scale back to Shars so Im waiting on that to come back before I start on mine. Did a couple runs in aluminum stock to check my methods and for practice. Im ready to go now as soon as Shars sends back my Z axis scale and display.

 

[1911ly]

Awesome. I am looking forward to your progress. Please take pics and start a thread about it!

My Tactical Machining jig arrived Saturday. I still need to order a 80% lower or too. I will look at the lowers in the link you posted. Thanks! you have tried those lowers for fitment in would be encouraging if the TM jig fits those lowers.

I used the DRO on the Z axis and followed the jig for the X and Y. I need to be not so lazy and use the DRO for all of it.

Give the JM lower and jig a try. I think you might be surprised at how well it comes out. If you don't plan on using it let me know. or if you have any extra Aluminum lowers that you'd part with.

I think you'll have a great time going the lower. It's fun and not that hard! And it sound like you have experience (maybe have done one?) and the right tools! Fun Fun fun! Not that hard with a mill.

 

[yournamehere]

I also have several different versions of AR15/M16 lower prints and would be willing to send them to anyone via email. I do know that it is legal to finish the lower with the full depth in the rear up to the point that if you drill the extra .125" go fast hole. Drill that hole and your in a world of hurt. I also know some factory lowers come with the location of said hole marked for educational purposes. Maybe someday we will have that option again.
http://www.colfaxtactical.com/docs/Fire Control Pocket with a DRO.pdf

This is a link for a step by step guide using a DRO and I have based my notes and process on this. Nice part is he has all of the X-Y positions so you dont have to get out the calculator with the print in hand to figure out all of it. Based on prints figuring out the rear lug cut can be confusing for those not familiar with print reading. Also for the trigger slot which takes a moment to figure out from prints going off the front pivot pin as CL.