Brownells BRN-180 Build
Part 2: Custom Wood Grip
The work on the Brownells BRN-180 continues! I am so stoked to keep progressing on the custom wood grip. This walnut is proving to be an excellent choice as it is hard and is easy to work with. In todays post I outline how I fit the wood blank to the BRN-180 lower receiver.
I started by inspecting my template which is the gray Magpul grip which I hope to imitate.
After closely inspecting the Magpul grip and lower reciever I noted the void in the center of the grip has two sections at the front and rear which both go straight down (perpendicular to the top surface) and I decided those ares needed to be cut first.
I started by using my Micrometer to measure both the lower receiver and the Magpul grip and used my framing square as a straight edge to measure and transcribe some guiding lines onto the blank.
After getting all of my guiding lines transcribed, I decided the best way to carve out the center section of the blank was to use an end mill bit, my floor standing drill press and cross vice.
This is my WEN 15" variable speed, floor standing drill press which I used for this precise work. (And if you are in the market for a awesome drill press I have been very impressed with this one)
Having this cross vice (Also a WEN product) was a MUST have for this project.
I bought a highly rated end mill bit off of Amazon which was designed for cutting metal (5/16"x4T"x2 1/2"). I decided to go with a diameter slightly smaller than the width of the lower receiver so I could be sure I could achieve a tight fit when I was done.
I started by cutting straight down to my lower limit line on the front of the blank.
I then cut down at the back limit line to a shallower depth (the same depth as the rear portion of the lower receiver).
I then locked in that rear depth on the drill press and used the cross vise and end mill bit to cut straight forward. I reasoned the angled portion would be cut at a lower depth than the rear vertical cut and so it was safe to bring that rear depth all the way to the front of the blank.
Using my Micrometer, I measured the width of the lower receiver and compared it to my initial cut and found it to be very very close.
I used the cross vice to shave a very small amount of material off both the left and right side until the fitment to the receiver was perfect. Now I knew the exact final internal dimensions I switched my attention to the angled portion of the cut out.
I determined the easiest way for me to determine the proper angle was to hold up the lower receiver to the blank and draw a line using the receiver as a straight edge. I then was able to use the aforementioned line to level the blank to that line in the vice. I looked at the angled cut on the Magpul grip and noticed it essentially was a straight line from the first two depth cuts I first made.
I made that the initial cuts and after test fitting it I realized I wouldn't be able to properly test its fitment without first rounding out the forward corners.
I used the lowest speed on my orbital sander to round the corners (although with a little future post foreshadowing here, I would recommend just using a sheet of 220 grit sandpaper on a hard flat surface instead of a power tool). After rounding the corners, the fitment was almost perfect but it felt like the angled cut was still just slightly too shallow and I took it back to the drill press for another pass. Unfortunately, on this final few minor passes with the end mill bit, I thought I had the depth stop set on my drill press and it was NOT; and when I was making a final cut, it went a hair too far which caught me off guard and I made a mistake and touched the moving end mill bit with my thumb and chewed it up pretty good.
This picture was taken after I superglued it back together the best I could, but my advice is don't touch spinning end mill bits.
Overall, I am really happy with how the grip is coming along. It looks great and fits great. Next up, I am going to drill some holes!
If you are interested in buying a Brownells BRN-180 lower you can find one at the following link;
(and at the time of this writing they are on sale and in stock!!)
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