Mega Machine Shop - Tumwater, WA

Mega Machine Shop GATOR GRIP AR-15 Lower Receiver

Available through Clinton Carrico -

There are two primary pieces to any AR-15, the LOWER RECEIVER and the UPPER RECEIVER. The lower is the part that the BATFE considers to be the firearm. It contains the trigger, safety, and the hammer which strikes the back of the firing pin. It also houses the magazines and has the stock attached to it. It does NOT contain the firing pin, bolt, bolt carrier, chamber, barrel, or sights. Those are housed in the upper receiver.

Both are primarily made from aluminum, although there are come composite units out there such as the CARBON-15. Right now we are sticking to recommending aluminum. You have a choice of forged or billet machined. The majority are forged, but there is a wide variance in finish and quality.

We looked at all sorts of lowers. Everyone in the AR-15 worlds makes them (or more correctly, finishes them) and most of them are very good. My favorite for a long time was PWA, but they have been out of business for years now. We took a look at the latest out there from many manufacturers, and saw quite a bit of varying quality - even from the same manufacturer. I've seen some Armalite lowers recently that didn't look good at all. I've seen some of the new Smith & Wesson lowers that looked pretty good, but I still haven't found anything as nice as what we are recommending.

I was leaning heavily towards Bushmaster or Rock River Arms until I found a company that had such quality and attention to detail that they really impressed me. The company is MEGA MACHINE SHOP in Tumwater, WA.

They make the MEGA lower with a feature they call the GATOR GRIP. After you have tried one of these - or have had the good fortune to assemble one from the ground up - you will see why I like them so much and why I am recommending them for building your own AR-15's.

The best source I have been able to find for these is Clinton Carrico of Carrizo'z ARmory. I inquired about the history of Mega Machine Shop and here is what Clinton was able to tell me.

When you look at these lowers, it is easy to tell that this shop pays a LOT of attention to quality. I have seen few companies make lowers that are this clean. It was actually very refreshing.

Mega Machine Shop uses 7076 T6 Aluminum forgings completed on a Mazak four axis horizontal CNC. The finish is hard anodized, and is rated at Rockwell 60 abrasive and 30 point. The finish on the MEGA lower is DARK. It is really dark. It is the among the darkest I have seen on an AR-15 and it is very even. The machine work is totally clean and very impressive. On the lowers I received only one had even a MINOR imperfection. It was cosmetic and almost invisible - not a functional impairment. These are possibly the cleanest lowers I have ever seen.

This is the WORST imperfection I have seen on ANY Mega lower. Not bad at all!

The GATOR GRIP is an area on the front of the magazine well that looks like a meat tenderizer. It is designed to give a textured surface that is easy to grip when holding the firearm with your supporting hand wrapped around the magazine well. It matches VERY well with the real meat tenderizer on the ACE SOCOM stock! I was not sure I would like it that much when I first heard about it, but I LOVE it!

The GATOR-GRIP on the front of the magazine well. I was not sure I would like this at first. I do!

I used a Rock River Arms lower kit to finish this receiver as I have had really good luck with them. Bushmaster also makes a quality lower parts kit, but the RRA kit is just a bit less expensive. In this case, the installation was easy. I won't detail the installation here at this time as there is already a resource on the Internet that you should check out. I have a link to it at the end of the article. There were no issues installing the RRA internal parts on any Mega lower we tested.

With a few tools, a little patience, the right instructions, and a complete parts kit anyone can put together an AR-15 lower. It is not rocket science. It is just a little work.

I have tested a number of upper assemblies on this lower and I have never had any issues with it. The tolerances all seem to be VERY good, and there was no play in between any good condition uppers and the Mega lower. As long as your upper has a good DARK finish, it will look fine atop a MEGA lower.

Here are a few shots of one completed Mega lower...

The FIRE and SAFE markings are on both sides of the lower. This one has been fitted with a special grip and an extended magazine release


In order to purchase your own MEGA lower, I would recommend that you contact Clinton Carrico. I have dealt with him and he is a good guy. It might take a while to get in touch with him as his firearms business is part-time, but be patient. They are WELL worth a bit of a wait. There is a link to his site at the bottom of this page.

As this part is considered to be a firearm by the BATFE, you will need to have it sent to your local FFL. You need to get Clinton a signed copy of the FFL for your dealer along with your payment for the lower(s), and have him send the lower(s) to your FFL. Your local dealer will charge you some amount of money - usually $10-$25 - fill out the Federal 4473 paperwork and run your background check. Then you are good to go.

Since I received our initial units, there are other variants of the MEGA lower. Mine are marked CAL. MULTI. A model marked PISTOL is also available, and there is now a flat top UPPER available with or without M4 feed ramps. It seems they also have a new model CNC machined from solid billet. From what I have seen it looks quite impressive, but we haven't seen one in person.

I will tell you that when I received our MEGA lowers some years ago, the price for a stripped (no internal parts installed) lower was $89. They have gone up, but they are still one of the more reasonably priced stripped lowers. You can also have Clinton install the lower parts for you if you would rather not do it yourself. Either way, the MEGA lower is the best value that I could find.

-- James Bell Jr. -

Click Here To Visit Carrico'z ARmory To Purchase A Mega Lower