Pre-Healy recievers and Pre-Healy guns, are really the order of what is available to us in MA. That being said, the question is, buy or build. If you buy, there are a number of AR-10 type rifles out there made by a variety fo manufacturers. DPMS pattern vs Armalite pattern guns take different magazines and have other variations in parts There are a number of factors to consider when building. I'm shamelessly bowrowing this from Ammo Land:
4 Things to Know Before Building an AR10
The AR10 Platform is NOT Standardized
The AR 15 is a standardized platform. Take any two AR 15s and there is a 99.99% chance their parts can interchange. AR10s are a bit different. They are not standardized for construction and different companies have different iterations of the AR10 design.
This leaves two main AR10 patterned rifles, the Armalite series and the DPMS series. When you choose your AR10 80 lower receiver you must make the decision to go DPMS patterned or Armalite patterned. Both patterns can result in a good rifle, but DPMS has a slight advantage when it comes to magazines and parts interchangeability with other manufacturers and even the AR 15 rifle.
AR10 Internal Parts are not Always Compatible
Because of the different patterns you’ll see barrels designed for both Armalite and DPMS, or upper receivers designed for Armalite and DPMS. These parts are not interchangeable between rifles. Once you select which pattern lower to use, you’ll have to select parts that are compatible with it. This includes your barrel and BCG. If you go with a DPMS pattern rifle you must use a DPMS barrel and BCG, the same goes for choosing the Armalite platform.
DPMS pattern AR10 80 lower receivers do have more options in terms of parts choice once it comes to assembling the rifle. Going the 80 lower route also means you’ll need a specific jig. The jig must be matched to the 80 lower. It’s not like AR 15s where there aren’t differences. When you choose an AR10 80 lower receiver make sure you purchase the compatible
80% Lower Jig with the right tools.
AR10 Lower Parts Kit
Because of small difference between lowers there are several parts that are only compatible with AR10 lower receivers. Small parts like the safety, trigger, and trigger springs can be swapped from AR10 to AR 15. Parts that will NOT swap are the following.
I am always on the hunt for the ban era AR-10B here in MA:
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