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1/20/2016 8:46 pm  #1

Just finished my Broken Arms 80% Lower

Hey Guys, I just this evening finished milling out the trigger pocket for my Broken Arms 80% lower. I must say that I was very pleased with the results. I purchased the Jig, drill bits and the end mill set and was pleasantly surprised at how well they were made. The fit and finish were superb.

Rather than using a drill press, I used a MIll/Drill which is a little more rigid than most drill presses. Because of that I skipped using the first plate. I did use plates 2-5. On the next one I will probably just use plates 4&5 after drilling 2 3/8" starter holes. I think with the extra rigidity that the Mill/Drill affords and taking the .060 depth of cuts I will be fine skipping the first three plates.

I was very pleased with the finish, even though I did have a few drill marks in the sidewall of the lower. I could probably file these out, but they shouldn't affect the operation of the rifle so I will most likely leave them. Eliminating the first three plates will solve this problem since I will only be drilling starter holes in the middle of the pocket.

Mike, I was going to use an end mill holder (as I said in a previous post) but couldn't find my 3/8 holder. I wound up using a collet which worked out just fine.

This is the Mill I used to finish my recever.


Last edited by tmc_31 (1/25/2016 7:42 pm)


2/27/2016 9:16 pm  #2

Re: Just finished my Broken Arms 80% Lower

Your lower came out very nice! Nice mill set up too...


8/26/2018 7:44 am  #3

Re: Just finished my Broken Arms 80% Lower

Several months after this I bought a 80% lower from Daytona Tactical for my Grandson. He did all the milling work on my machine. He was able to successfully complete his lower in about 3 hours with minimal input from me. The Daytona Tactical lower seemed to be tapered somewhat toward the bottom as it fit loosely in the Broken Arms jig at the bottom. A little shimming took care of that problem. The Daytona lower was 7075 aluminum so I was a little concerned about how well the milling cutter would work. That carbide cutter breezed through the 7075 aluminum just like it did the 6061-T6.

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