Trying my luck at finishing a lower. Any recommendations on a jig I can use with a drill press?

Get a router based jig. Results are much better.  If you don't want to stuff when you're done with it sell the jig when you're done and get 80% back (pun intended) and sell the router on CL for ~75% of new. 

Usually I disagree when ones asks which item X should I buy, and the first answer is, don't buy any item X, buy item Y instead.  

But in this case, I can't agree more.  Better results, less headaches and yes, you can sell it when you're done without much loss.

If you don't own a drill press, I would not recommend one for doing lowers, due to the side load that has to be put on the spindle, which is was not designed for side load.

If you are just going to do a few lowers, get a router and a router jig, things will go easier and much cleaner lowers will be turned out.

http://brokenarmory.com/ These people make a jig.  Like mentioned a drill press is not really designed to mill with but I can't say a trim router made for wood is really designed for side cutting metal either. There are risk using any tool incorrectly I would guess. I would not recommend doing an 80% lower to anyone as it makes a mess and it is a pain to contain the mess and clean it up. It cost a lot to set up to do it also.

From posts I have read about using a router the drill press method will take longer. Takes me about 6 hours to do one on my drill press. You have to really know the ins and outs of the drill press to get good results. Some depth stops I have seen have a lot of play in them which could mess up depths if not careful. The tables are not necessarily level in both directions which can throw the bit angle off if you do not compensate for it by shimming the jig where needed. Leaving one thing loose once when adjusting for the different drill bit sizes and lengths can mess it up. If you break one of the small bits off in the lower you can add about and hour to cutting it out with a dremel tool . The hole that drills out into the grip thread area will pop a bit quick it you do not know to watch out for it.

Wouldn't recommend a drill press jig. Almost fudged up my wrist, and it pretty much fudged up my drill press.

I found the drill press method rather simple, depends on your skill with the press and a understanding of how metals behave with any particular method.

Router or mini mill.

I think that the router method is better, because you don't need much training/ learning. The router method is a lot simpler, and harder to fudge up. Oh and cheaper.

I have mini mill but still use a router for AR lowers. I find it much faster with similar results. I would not under any circumstance attempt it with a drill press. The spindle of a drill press being unsupported laterally allows too much chatter and the resulting finish is unacceptable to me.

I don't recommend a drill press but the ones I did on one had a better interior surface finish than any router jig pic I have seen. You could see yourself in the reflection on the ones I did. There was no chatter on the press I used because you ride the jig top plate along the side cutter. You can lube it as you cut better also.

All that matters is that the tooling IS designed for cutting metal. The motor really has no idea what tooling is installed or what material it is cutting as long as you do not tell it. :)

Here is a pic of one that I did with a router. It is typical of the type of results that you can expect from a router based jig.

GREAT...

now I need an 80% lower..

Y'all cost me money on nearly every one of the threads in "Build It"

$26 for a raw unmarked lower, $32 for a raw Safe\Fire marked lower and $45 for an Anodized Safe\Fire lower at RightToBear.com

That's about the best price on lowers I have seen.

It's possible to spend a lot of money buying stuff to build a lower that works just the same as one that's $130 complete from PSA.  You also can finish an 80% aluminum lower using the $35 jig from EP Armory and a ~$30 trim router from Harbor Freight (consider it disposable) and a ¼" HSS straight router bit.  Saw a V opening in the router base so that it will clear the buffer tube mount when machining the hammer pocket, drill a 5/16" hole all the way through the blank in the trigger slot then insert the router bit into the hole and start removing aluminum with transmission fluid for cutting oil, but don't hog out lots of material in a single pass.  Taking smaller bites you can cut one in around two hours time that works and looks just fine.  Clear the chips often and check your depth of cut every time because the router collet may not solidly hold the cut depth, and finish with a light pass at the final depth.  Depending on your particular lower, the jig's registration pin may need to be slightly driven in/out so that the jig properly closes on your lower.

....yeah....but where's the fun in that 

I need to get some vinyl stencils made so I can practice electro etching on some scrap 7075 before I attempt it on my lowers.  

Agree - just pointing out that a fella doesn't need to spend $500 on tooling just to have a rifle in the end.  Now $500 on tooling for it's own sake is another matter that I could support if I had more than $1.98 free.

I'm happy with my lower and a little bit proud that I made it myself on a retired guy's budget, and making it was a fun way to occupy some time.  I'm double happy with the JP adjustable trigger I fitted that's wowed everyone who's tried it.