A few random thoughts....

I only start with already anodized “80%” Lowers. Here’s a photo of one I cut...



First thing, make SURE you have the receiver tight in the jig and all parts of the jig tightened up. I keep seen several members comment that they screwed up their lower because they failed to make sure everything was TIGHT! During cutting occasionally check the back attachment that threads into the receiver extension (buffer tube hole)

Before cutting make sure the cutter is TIGHT! If the cutter comes loose while in use......NOT GOOD! If using one of the other types of jigs CHECK THE BIT AFTER EVERY CUT!

If using the newest style jigs (5D Tactical PRO or Modulus Arms Extreme) check at least once during cutting that it’s still TIGHT. When I was using older style jigs including ones by Modulus Arms and by 5D Tactical, I could NEVER get as smooth a cut as the newer jigs where the mill bit is held in the holder and is threaded directly onto the router shaft.

For cutting oil I use WD-40 Spray Silicone, use whatever you’re comfortable with, just use A LOT!

I replaced my drill bits with ones that a member here recommended, McMaster Carr Chip Clearing bits. They cut NICE!

Speaking of drill bits, I do use a drill press. Make sure the table is “square” to the bit. And double check the table with a Level.

Again, when drilling, use A LOT of lubricant.

WHEN you “blow” the carbide mill bit (and you eventually will) I’m currently replacing it in the holder with a radius bit. It has a small radius on the corners of the cutting edges and I’m of the opinion that it will hold up better. I’m using one with a .030 radius currently, I might try a .060 if I can find one.

SLOW is better, I go halfway (or LESS) on adjusting my cutting depth on the “hash” marks.

ALWAYS cut in a small CLOCKWISE motion.

FIRMLY hold the router, pushing down at all times. Using a foot pedal control is probably the best way to start and stop your router.

I only use the router that 5D Tactical rates the highest....the DeWalt DWP611. Go cheap, get crappy results.

Attach a shop vac to the port on the rear of the jig, not only will it help keep the sharp aluminum chips off of you, it will help keep them out of the receiver for a smoother cut.

Vacuum the bottom of the jig between adjustments, vacuum the top plate of the jig between adjustments, and vacuum the inside of the receiver out between adjustments.

When it’s time to change the router guide pins, keep a pair of pliers with the jaws wrapped in electrical tape handy, sometimes they stick in the bottom of the router bottom plate. It doesn’t take very much pressure to remove them even when their “stuck”. DON’T crush them.

You really should wear eye and hearing protection while cutting

ALWAYS wait for the router to completely stop after a cut, when starting a cut TRY and keep the bit centered in the start hole so the router doesn’t start up against the receiver.

And this is my personal option/preference! On all of my “80%” lowers I install the Rise RA-140 Drop In trigger (cassette type) and I use KNS Anti Rotation/Anti Walk pins. The best version of the KNS pins is offered by Spike’s Tactical. They offer both standard KNS pins and a version I haven’t seen available anywhere else, the hammer and trigger pins are melonited. The version I prefer is....

KNS ANTI ROTATION PINS GEN 2 MOD ST

SKU: SLA0607

$38.00

Here’s a photo of the Spike’s version pins...

Keep in mind, I STARTED cutting “80%” Lowers out using a Little Machine Shop mini mill. I can cut out a lower FASTER and as nice using my 5D Tactical PRO jig.

Here’s a LINK to my original review of the 5D Tactical PRO jig. It might give you a clearer view of how the jig works.

When I used my original Modulus Arms jig, you drilled several holes in the FCG pocket. It was a less than desirable method.

As to taking shallow cuts, it’s not necessary but you lessen the odds of “grenading” your carbide mill bit and you achieve a much smoother cut. It’s not required but even though you can’t see it and functionality it’s the same, I want it to be as nice as possible.

I wish I had hung onto the paper work, it’s a 4 flute .030 chamfer carbide cutter.

OST.  I have 4 lowers in bound.  This will be my first attempt at doing 80% lowers.

Still need to find a place that has the 5D jig in stock though.

I did a comparison awhile back....LINK