Latest ArmaLite retro project

[browningautorifle]

I had a Costa Mesa back in about '76. I also had another about 20 years back and used modified AR mags due to the lack of proper 180 mags. I like the billet lower...

[painter777]

Let it suffice to say, I want to be able to shoot my "Little Armalite" like I did when I carried it as a trunk weapon in the 1980s....

Exactly, and be able to afford to feed it, unlike the one in the GB link I added.

Charlie-Painter7777

[imarangemaster]

Picked up my NDS18S lower yesterday. Wow, that is one nice piece of forged aluminum. VERY sturdy lower. May get time to put it together and hang it on the upper today or tomorrow. PICS forthcoming..

[imarangemaster]

Sweet! Everything went together perfect. With the AR180B and NDS18S lower, the bolt hold open is set for AR15 magazines. The AR180B upper has clearance for it, but the original AR180s do not. Their BHO is contained below the level of the upper, and a spring detent acts against the bottom of the upper to keep it from engaging until the mag is empty. WELL, I refused to cut a mint Costa Mesa upper to make a notch.

The armorer/tinkerer in me kicked in: I modified the AR180B BHO by flattening it out straight, then bending the end up at a 45 degree angle. I filed the rear edge of the mag follower at a corresponding angle. The result is that it feeds the last round from the AR15 magazine (with modified follower), without a hiccup, and actuates the BHO when the mag is empty...ALL without screwing with the original upper.

The bonus is, that by using this angle instead of the AR180 low step, the mags still actuate the AR15 BHO when empty. That was actually the plan. Now I can modify the rear of all my Magpul followers in ALL of my 30s so all will work in either my AR180 or my AR15 SP1 Carbine!

Pics tomorrow, including the modification.

[imarangemaster]

Teaser:

[imarangemaster]

More: The BHO tab was originally a stair step affair that rose up 1/8", then over 90 degrees to be the actuator that engages the square edge of the BHO activator on the magazine. I flattened it in a vise, then marking then, bent the last 1/4" or so upward at a 45 degree angle. With the BHO all the way up, only the tab that engages the mag follower extends up above the level of the bottom of the upper receiver. Before, it needed a 1/4" notch cut in the bottom of the upper to move upward. As you can see, only the small back rectangular area on the rear of the mag follower, needed to be filed at a 45 degree angle to match the angle of the BHO actuator tab. Because of the design of the standard AR15 BHO ( a long tab extending forward) it still hits the follower on the front of the 45 degree slope, and activates the BHO.

[imarangemaster]

Unfortunately, in Californication, any new builds have to either have fixed magazine (no more bullet buttons) or be "Featureless" (without pistol grip, flash hider, or collapsable/folding stocks. The up side of featureless is that you can use standard magazine buttons. I replaced the Armalite three prong with a CAV brake (that allows bayonet, and is a decent muzzle brake also), a AR180B fixed stock, and a Magpul MIAD grip with Exile Machine "Backfin" with thumb rest. Actually, it gives a VERY comfortable grip - but is not a evil "pistol grip" according to Penal code.

Since I am LEO (retired) I can keep my high cap mags, unlike every other person behind enemy lines in Californistan, who are now stuck with 10 rounders. While I feel this high cap ban is unconstitutional and unfair, I don't plan on using ten rounders in solidarity (not that ANYONE has turned any in, LOL)!

[imarangemaster]

My Magpul Gen 3 30s are full of MK262 MOD1 77 grainers for my 1/7 twist SP1 Carbine clone, so I won't bother with those followers right now (as the Costa Mesa upper is 1/12" twist and need M193 55 grainers). All of my Aluminum USGI 30s, though, I will modify to work in both platforms...

[painter777]

Really looks sharp.
i appreciate you sharing it.
Sure wish I could fire a few rounds thru it.
Really nice job IRM !

Charlie-Painter777

[browningautorifle]

I'd like to at least be there to watch the testing...