View Full Version : Mega Arms Billet GTR-3H lower & Billet upper & Mega Grip Review & how-to video

10-12-2012, 6:33 PM
I decided to build another custom rifle and set my goals to build a very unique match AR. I wanted to go a different route this time for the upper and lower receiver set. My past experience with Mega Arms products was great so I opted to use their Mega Arms Billet upper and lower receiver set. Out of all the manufacturers which offer billet receivers it was not difficult to go with Mega Arms with their great reputation and customer service. As a right handed shooter I have never cared for ambidextrous features, but for those who need it, they offer an ambidextrous version as well. Along with the GTR-3H billet lower Mega Arms also offer another billet model, GTR-3S, which is more suited to mate to a standard forged upper. The difference is only aesthetic between the 3S and 3H. The 3S has a round profile while the 3H has a hex profile around the buttface/buttstock area. The 3H is suited for mating the billet hex profile upper or the now discontinued MTS upper. With regards to the MTS Monolithic line of products, Jason and the crew at Mega Arms are working on a new improved design which will be released in 2013, if you want to read about why the MTS is no longer being produced feel free to read this link: http://megaarms.com/2012/07/monolithic-upper-notice/ I was told by Jason the new designed MTS series will fit the GTR-3H lower receiver which is great for those looking to upgrade in the future.

Mega Machine Shop created a branch strictly dealing with firearms which they named Mega Arms. They makes all their billet receiver sets in house with precision high end machines so the specifications and quality control is top notch. Being produced in the USA is important to me for this build, as I want to use the highest quality parts while also supporting our manufacturing here in the States. Keep in mind there are a handful of manufacturers which mass produce AR receivers and send them out for final finishing and stamping to all the other companies. Mega Arms does everything in house, so you only have one source to deal with, which is a big plus. This question gets asked a lot and I have covered it in a couple different reviews but I will quickly go over the Forged vs. Billet question. Generally a forged set with properly setup dies and flow control will be stronger due to the way the molten metal grains and molecules align in the forging process making the finished product denser and stronger. However there are multiple forging methods and not all are equal. I have seen companies simply fail because they donít have the proper tooling and experience in manufacturing. Mega Arms has been around for a long time with customers ranging from Aerospace, heavy-equipment to firearms and all the products are made in their ISO 9001:2008 registered facilities, which speaks volumes when it comes to quality control. They use the highest quality 7- series aluminum for their entire AR-15 product line whether it is billet or not. Some companies use 6-series aluminum to cut costs at the expense of durability and strength. Mega Arms exceptional quality control and commitment to using the highest quality material is why they stand out above the rest.

The GTR-3H lower and billet upper receiver is CNC from a block of 7075-T6 aircraft grade aluminum which is 70% stronger than 6061 aircraft aluminum. While both alloys are light and strong enough for most products, 7075 is a much stronger alloy with greater amounts of manganese, copper, zinc and chromium which results in much higher corrosion resistance and the main reason it is used over 6061 for receiver set. As with most soft alloys like aluminum it will not withstand long term abuse so it is anodized and sealed to a hardened surface of 60 Rockwell. The finished product has a nice consistent flat black look which matches a lot of Mil-Spec blued/parkerized finishes on other components. One of the best features of this set is the zero play fit between the upper and lower receivers. You could not slide a piece of paper between the two halves if you wanted to. These tight tolerances are a testament to the quality control and precision of the CNC programmer. The tight fit between the receivers helps with improving overall accuracy. The play between receivers is an issue which a lot of people just live with or alleviate by using different style takedown pins or wedges. To be entirely free of any play to pursuit the ultimate accurate rifle, you need to spend more money to solve the problem. Mega Arms has done this for you by providing a nylon tipped tension set screw which is part of the lower receiver. This tension screw helps eliminate any possible play between this lower receiver and other Mil-Spec uppers from any other manufacturer. The Engineer in me naturally wanted to see if I could improve the current tension setup so I though about converting to a dynamic tension system. I will update this review as I test out different dynamic tension systems. While assembling the receivers, I noticed when using different pivot/takedown pins from different manufacturers, it resulted in different overall fit between receivers and gaps up to 0.5mm with some play. So not all pivot/takedown pins are created equal and this is where the Mega Arms tension system is so critical in taking the guess work out of which pin set and mating upper to use. Donít forget to use thread locker on the tension screw and the best way to adjust it is after the upper and lower is mated. Aside from the tension screw what really set this billet lower apart from its forged counter part are subtle details in the unique shape and design. There is an integrated trigger guard with additional material left in the area for strength. The same strength design queue is used near the buttface/buttstock attachment end for potential use with more powerful caliber configurations. The magwell is enlarged and flared at the bottom which serves both as a functional and aesthetic feature which allows easier magazine insertion while aesthetically looking different from the conventional magwell. One major advantage of this flared magwell is the milled horizontal grip marks on the front surface which provides a more comfortable slip free surface to grip if you donít have a forward pistol grip. The billet upper receiver really finishes the complete style and look of this receiver set with the hex style shape and sleek lines. It is quite distinguishable compared to a forged counterpart with heavily reinforced walls for added strength and rigidity. When it comes to looks and style, it is all subjective, however there are functional differences like the shell casing deflector angle set to 60 degrees which is great for your neighbor at the range. This billet upper comes complete with forward assist and dust cover already installed. It also features M4 feed ramps and has laser engraved ďTĒ numbers. The billet charge handle is also made of 7075-T6 and has the same treatment and Rockwell rating as the receivers. It has an anti slip grip handle and the locking latch has a ribbed grip design. I noticed while assembling the upper, due to the hex shape of the billet upper receiver it will not fit in a standard action block, but that did not stop me from using the action block and some rags to pad the receiver and still have a firm grip to complete the assembly. This build is not complete without the Mega grip which is made by Hogue and stamped with the Mega Arms logo at the Hogue factory before shipping out. Similar to a standard AR-15 Hogue grip, which I also use on my other rifle, this has the same exact comfort and amenities to accommodate a Samson field survivor kit. Iím a huge fan of Hogue grips and use them on all my firearms, so this grip with the matching Mega Arms atomic logo on the lower receiver just puts the finishing touch on the complete setup.

This is simply a great product by Mega Arms and if price is not a factor I donít see a reason not to purchase this Billet receiver set. This will set you apart from others with the unique style and shape and although functionally it will perform similar to a forget set, it has features which are worth the price tag in my opinion. The fit, finish and quality are outstanding and customer service is fantastic. You only have one source to deal with, being made in house here in the USA and unlimited support should you need it. If you are looking for a billet set I would recommend this to anyone.

Video Install Guide: http://www.youtube.com/watch?v=0hatvidG5n4


10-12-2012, 6:33 PM

10-12-2012, 6:33 PM