Author Topic: American Spirit Arms 95% lower  (Read 5673 times)

Offline falee642

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American Spirit Arms 95% lower
« on: July 14, 2013, 05:46:09 PM »
Has anyone used this lower as a project with Justin's jigs?  Does the shelf area have to be completed as per Justin's tutorial?

Offline NorthStar

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Re: American Spirit Arms 95% lower
« Reply #1 on: July 26, 2013, 06:14:10 PM »
You do not need to mill the shelf with these. You do have to drill the pistol grip hole, and the safety selector hole, along with the front pivot pin hole in addition to milling the FCG area.

Offline vwgtiturbo

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Re: American Spirit Arms 95% lower
« Reply #2 on: July 29, 2013, 09:37:58 AM »
Having just finished two of these lowers (not with Justin's jig), you do NOT have to drill the pistol grip hole. It is already done on these lowers. I'm guessing that NorthStar has NOT done one of these lowers (the front pivot pin hole is ALSO done already).

The only items you need to do with the ASA 95% lowers is: 1) Trigger/Hammer pins (5/32"), 2) Safety Select (3/8"), 3) Mill FCG, 4) Mill Trigger Slot, and 5) Mill a tiny bit of the shelf, just behind the FCG (the area that the upper receiver tang sits in is already done).

Offline bergermeister

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Re: American Spirit Arms 95% lower
« Reply #3 on: September 21, 2014, 07:22:39 PM »
I have some information for those who are interested in finishing 80% lowers.  I speak from experience using the equipment noted.  This system uses a hand-held router. I would strongly advise anyone wanting to try this method to purchase a so-called 95% lower. American Spirit is one and I decided that IF I decide to build another this would be my choice.  In my mind, the accuracy of the side-to-side mill out where the rear upper lug inserts into the lower should have a minimal play.  This was not the case with the 80%'er (lower) I built.  I have devised a 'fix' for my lowers error- but I digress.

I purchased a MODULUS jig and lower.  Their innovation was to be an improvement from the run-of-the-mill jigs inasmuch as MODULUS had a system to set up on the center line, making the jig universal to AR-15 lowers.  A nicely done manual explained how to set-up, drill and mill out the fire control cavities; and was followed precisely.  It is cleaned up with a 1/4" four flute carbide cutter.  In my opinion, at 25,000 rpm the 1/4" cutter has excessive run-out.  In this case it was 6061 and not 7075 aluminum.  I don't know if there would have been more of a problem with 7075 or not.  With the 95% lower the rear cavity is already cut and chances of screwing up the lower are less.

If you want to try the router system I have the following suggestions: 1) Purchase a router speed control such as from Harbor Freight ($20.00) and crank it way down.  (2) Watch very closely for any center line shift (mounting screw play) when changing back and forth from drilling plate to router plate as you progress.  (3) Keep in mind that the chatter can cause the mill to plunge if it is not really tight. (4) Do not lean on the 1/4" cutter as the shaft is extended and you will induce run out. Maybe this will be of help to anyone wanting to try a router.

I tried to write this evaluation on AR15.com but was kicked off their forum, as well as another guy I don't know for "PIMPING" a product.  Does this sound like I'm pimping MODULUS  >:(  I hope maybe some of the people from there also come here so they can see it was evaluated it like I said it would be.  ;)  Thanks!