Hello. I just purchased an 80% lower. Haven't even received it yet. I am looking at building my own home/personal defense and plinking (to gain proficiency in gun use). I don't know the first thing about the various kits, and the acronyms.

I have been watching all kinds of youtube videos, and it seems like it will be decent enough to build the lower up. Once I am at that point, I don't where to move to next.

I am on an extremely limited budget, and am probably going to be buying a part every month or two. I would prefer to have plenty of research before I decide on a specific part. This is why I am here. I am looking for advise from those that have done this before.

Palmetto state armory is your friend. Everything you'll ever need at a damn good price.

stupid phone double posted...

Why choose a curved trigger or a straight? Other than the obvious shape differences, is one targeted at a specific function? Or are they solely based on the feel of the trigger?

Are you aware of what kind of tools are required to "finish" a 80% lower?  On a extremely limited budget?

+1

Their premium stuff is really nice, as are the "freedom" series.  Some folks have had bad luck with the PTAC uppers, but I bought one, and three of my friends did as well, all within the last month.  Fit & finish was fine, and they shoot well.  The "modified heavy" profile on mine actually groups just a hair over MOA at 50 yards with a 3 MOA red dot.  If the budget is really that tight, I'd consider the PTAC uppers.  The black one has a government profile barrel (lightest), the stainless are either medium or heavy, depending on what they have at that time.  



An important consideration.  Unless you have a mill or access to one, you'll definitely need a jig.  And even with the jig, 80% lowers done without a decent vertical mill tend to turn out a bit, well.....fugly.  Yeah, I've seen videos of guys hogging them out with a router, but the odds of screwing up are really, REALLY high.

Unless you have access to tools and the skill to use them you should probably return the 80% lower.

+1. Not to mention a cheap forged lower is likely even cheaper, which fits your budget better.

And if youre new to ars, building one is simply wasting time and money that should be used learning to be proficient with the weapon. No warranty or recourse if it doesnt work either which is then even more wasted time.  My $0.02.

That doesnt mean building isnt fun or something you should not do. It is. Since you have the stuff, might as well, but dropping the 80% is probably a really good idea. The chance of you having issues with that lower is high....

Just a word of advice...

I don't know what your budget is, but if you want to get the most bang for your buck, spend your money on the barrel, bolt, and trigger.

Noveske,  Rainier Arms, PSA, and BCM have good barrels.

Young Manufacturing, PSA, and BCM have good bolts.

Geissele and AGL have good triggers.

If you are on a limited Budget I have no idea why you started with an 80% Lower as it will be far more expensive to finish that lower than to outright purchase a Complete lower from PSA as well as a few others for $50.00 more or less plus FFL Fees.  I say this as I really looked into the price difference between an 80% Lower and a Complete bare lower and well you guessed it the Complete Bare lower from PSA Won out.

An Aero Precision lower cost $55, an Aero upper is $50, a good BCG is $70.

Anything over $100 is shipped free.

FFL transfer is $20-$30

That will get you a very solid start.

80% build isnt cheap if you dont have the tools before hand but if you go in on one with a bunch of friends like i did for my 80% build that knocked the price of the jig needed to finish out the lower.

First off Welcome to the forum! Everything I have learned has been through ARFCOM. I could never have been as successful as I have been without the help, guidance, tips, good natured ribbing, etc. from the ARFCOM Members! Thanks to everyone for sharing your knowledge!
Milling an 80% is not usually the best way to stay within a "budget" That being said it is very rewarding to finish a lower. If you are a tinkerer and have basic mechanical knowledge it can be done with a high level of success. What 80% lower have you purchased? Have you also bought the jig that's recommender for the lower? What milling machine do you have? Is the lower a forged aluminum or is it one of the polymer types? Polymer is NOT the best lower material, but it is another option. You won’t get a lot of love here if you are milling a polymer lower. That being said polymer lowers do have a place in the hobby. I for one have never used one, but my father-in-law and my brother-in-law both have built rifles with polymer lowers. In my opinion (which doesn't amount to much) I would only use polymer for a .22 based rifle. I use Tactical Machining forged lowers as well as their jig. I have completed 6 rifles with their lowers (1 raw aluminum and 5 pre-anodized). Their jig is very easy to use with the right setup. Safety while milling lowers is paramount. It is highly NOT recommended to use a normal drill press with an end mill. The chuck can and will usually come loose and destroy the lower and tear up any soft pink skin that's anywhere near the lower. Also if you have to move the jig around by hand on the table while milling you are asking to lose a finger or worse!! Older drill presses have a draw rod (may not be the most accurate terminology) that holds the spindle/chuck in. My combo machine uses this type. Remember Drill Presses are not designed for the "side loading force" that “Will” happen when you are using an end mill.  
I use a JET Milling/Drill press combo machine that I have in my shop at work. I am a Power Plant mechanic, so I am skilled in using drill presses, end milling, precision measuring tools, etc. My machine has an X/Y table and a very sturdy milling vise. Remember there are quite a few things you will need besides just the lower. You will need good tooling (end mills (3/8' & 5/16"), (5/32") drill bit (trigger/hammer pins), 3/8" drill bit (safety selector), calipers, etc. Most "cheaper" jigs come with tooling. Be very careful of cheap bits and end mills (China) An easy way to check the tooling is to roll the bits and mills on a piece of glass to check the trueness of the tooling. I use 2-Flute Centering Carbide end mills. I drill my hammer and trigger (5/32") pins and safety selector (3/8") pin holes first. I have found that it prevents walking.  There are various opinions on this, but this is what works for me. The jig I use has drill bushings on one side so you index the holes exactly where they need to be. Drilling the pins slowly with "step drilling" is very importance. Speed of your machine is also very important. I use 2500 RPM’s setting for my milling of the "fire control group and shelf" area. I use approx. 800 RPM for the safety selector (3/8") hole and trigger/hammer pins (5/32") holes. My friend is a machinist and he told me to use Kerosene for the cutting fluid. I can’t use it at work but he says with aluminum you can’t beat it! I use Kroil for my milling/cutting fluid (tons of cans at work).  Also if you ARE using a polymer lower, too fast a speed will burn/melt the polymer so plan to slow the speeds down.
I realize this is ALOT of info, but I'm at work on graveyard shift alone so I may be rambling! I'm sure I missed some things.  I would be more than happy to assist you with any other questions you may have. Also I can shoot you some pics if you want me to.  I am NOT an 80% Builder Guru, but if I can help just let me know! Also I am willing to be publically flogged if my advice is not sound. I learn stuff every day on these boards.
Just be very careful!!!  Measure everything before you start, take your time and Have Fun. If you are like the rest of us that have “Black Rifle Disease” (BRD), there is no cure!
Tony
PassoGunner24

I assume that arfcom is this website? This is why I created a membership. I wanted to tap the knowledge of those that have proceeded me.

I wanted the reward of building my own gun, and not having to go through the ffl procedure. I do not believe that it is a hoop that I should have to jump through.
I have experience with various tools, and have watched several hundred videos of how-to's and such. I have spoken with some gun guys in my area, and I believe that I can do this.

The 80% I purchased is from Ares Armor. Yes, it is polymer, but this is what I wanted to use. I am aware that I will have to go slow while clearing this type out. They had all the jigs necessary with the lower.
Lol... I guess I'm not looking for love, as much as I am looking for what the next steps should be. I wanted to try my hand at the polymer first, and if I can get it to work, then I was going to move up to metal.

I have access to a mill, a drill press, and what ever else I will need to machine this out properly. I do definitly agree that chinese bits are not the best, and I will also have access (or purchase) the proper bits.

I noticed that Ares armor is not listed anywhere on the site. Is that not a reputable company?

I mean no disprespect, but I have a couple of bones to pick here.  See next post due to "new account 2,000 character limit"

The FCG pocket radius spec is .218", which means using a 7/16" (.4375") cutter with at least a 1.3" LOC, not a 3/8" mill.  I have no idea why so many companies supply/recommend 3/8" cutters.  Sure, you can use 3/8", but the spec calls for 7/16".  The rear take-down pocket and trigger slot are 5/16", and you'll need a cutter that is long enough to get .630" into the lower without bonking the quill into the receiver extension housing.  I use an undersize .298" cutter for the trigger slot so that I can guarantee a .312" finished width; a .312" cutter moving through material at 100% of its diameter WILL NOT produce a .312" wide cut. More like .313"-.315", and that's if you have a solid machine.

2 flute or 4 flute is a personal preference thing, but on 7075-T6 aluminum, I prefer 4 flute HSS end mills, and I cut dry.  4 flute mills are less prone to chatter, and will give a smoother finish.  HSS is plenty hard to hold an edge in aluminum, and can flex a bit without breaking.   Carbide cutters don't flex.  Period.  They're extremely hard, and a better choice for machining steel, but they will snap in a heartbeat if they get loaded too hard, usually from clogged flutes or someone running the feeds too fast.  If your lower is 6061, you need to use a cutting fluid; 6061 of any temper will clog flutes if cut dry.  Just about any thin oil will work; I like penetrating oils, as it's easier to blow away thin oil filled with chips than some kind of heavy thread cutting oil.  Automotive engine coolant works, too, and I use that a lot when cutting steels because it cools the cutter better and doesn't produce the smoke that oils will at the temps you reach cutting steel.  But I digress....





continued..........

2,500 RPM is too fast for roughing on a manual machine.  That's toward the lower-middle range of final pass speeds.  900-1,200 is where you should be for roughing, coming within 0.005"-0.010" of final dimensions.  Running cutters at those speeds when hogging out large amounts of material generates a lot of heat, which will dull the cutter.  I run 1,080 RPM for roughing (I cut the FCG in three steps; first pass at depth of .630", second at 1.240" and final at 1.249"), and 3,100 RPM for final pass.  It produces a very nice finish.

http://i110.photobucket.com/albums/n117/Hunter2506/IMG_1121_zpsb8ce30f4.jpg

Do not dwell:  moving too slowly through material is hard on edges, regardless of material, RPM or use of lubricants/coolants.  Basically, you polish the edge right off your cutter.  If you need to stop, back your cutter away from the material, or better yet, raise it out completely.

If using a jig, you can get away with attacking the selector and pin holes with 3/8" and 5/32" jobber drill bits.  If doing it "fee hand" as I do, you need to use centering cutters and preferably drill the holes undersize and use reamers.  I use a #24 drill for the pin holes and a U (.368") for the selector, then run precision reamers through for final diameter.  The aforementioned 800 RPM is in the ball park for drilling, and, as mentioned, you need to step drill.  That is, don't try to bore the hole all the way through in one shot.  Drill in 1/8" or so, then back the drill out.  This prevents chip build-up, which dulls drills, clogs flutes and causes bits to deflect as they're passing through.  It also causes ugly galling.  If you have compressed air top clear the chips, even better