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"Pinned" AR uppers

MartyEGVboyMartyEGVboy Member Posts: 146 ✭✭✭
edited May 2014 in Ask the Experts
I'm wanting to Frankenstein an AR together (I have the lower already) and I'm looking at PSA at their uppers and came across this in several listings:

"This upper is not pinned and welded, all NFA rules apply"

What exactly does that mean? Not all the ads are listed that way. Does this defray some cost to PSA (less labor fewer dollars)?

I'm a total newb to AR stuff (funny how that rhymes with boob)...


  • TANK78ZTANK78Z Member Posts: 1,279 ✭✭✭
    edited November -1
    with out more info or a better description, more then likely they are referring to the flash hider,and/or a short under 16" barrel which would make it a pistol only build or a rifle that will need a federal tax stamp in those states that allow possession of short barreled rifles.
  • MartyEGVboyMartyEGVboy Member Posts: 146 ✭✭✭
    edited November -1
    Thanks. I hadn't noticed that that applied to those 14.7 barrels uppers (and shorter, I'm sure).

    So what's pinned and what's welded? For my edification -- I'm looking at 16" barreled uppers (I let the price [$319] drag my eyes away from the length spec) [:I]

    Here's the link for the curious:
  • Horse Plains DrifterHorse Plains Drifter Forums Admins, Member, Moderator Posts: 37,972 ***** Forums Admin
    edited November -1
    Pinned and welded, means the flash supressor is permemently installed by pinning and welding. This allows the flash supressor to be considered part of the barrel, making the barrel lenght 16" or more, so it no longer falls under NFA rules.
  • beantownshootahbeantownshootah Member Posts: 12,776 ✭✭✭
    edited November -1
    Clarifying what's been written above.

    For a rifle to be legal the barrel has to be 16" long or longer.

    Shorter than that, and you'd need to register the gun with the Federal government as an NFA item, pay taxes, etc. Even then, short barreled rifles like this may not be legal in every state.

    One way to get absolute minimum possible length on a legal AR-15 is to have a 14.7 inch barrel, then permanently attach a flash hider on the end of it.

    If the flash hider is PINNED and WELDED (or silver soldered) in place, then its legally considered a permanent part of the barrel and the length of the permanently attached hider will bring the finished barrel up to (bare minimum) 16" legal length. EG 14.7" barrel + PERMANENT 1.4" hider = legal overall barrel length = you not in jail for 10 years.

    If the barrel is 14.7" long, but the flash hider is NOT permanently affixed (ie pinned and welded), then legally, you can only put that upper on a handgun (where short barrels are allowed). If you were to put the short-barreled upper onto a rifle lower, you'll have a "short barreled rifle" requiring Federal registration, etc.

    So assuming you otherwise liked it, you could still buy this 14.7" lower, *BUT* before you put it onto your gun (and optimally before you even take it home), you'd really want to have a gunsmith permanently affix the hider into place for you.

    Its probably possible for a skilled person with the right tools to do this at home. . .personally, I'm not such a skilled person, and wouldn't even try.
  • MobuckMobuck Member Posts: 12,964 ✭✭✭✭
    edited November -1
    As long as your lower has never had a "rifle type" stock on it, it's still OK to assemble as a "pistol". If you bought a bare lower and assembled it yourself, it could still be a handgun and therefore, legal to have an upper with under 16" barrel.
  • rsnyder55rsnyder55 Member Posts: 2,626
    edited November -1
    Depending on the state, it may also depend on how the receiver was registered when purchased.

    In CA, if you plan on using a lower for a pistol build, it must be registered as a pistol when you purchase it. Conversely if you plan to use it for a rifle build, it must be registered as a rifle when you purchase it.

    Edit: Corrected error in last sentence.
  • MartyEGVboyMartyEGVboy Member Posts: 146 ✭✭✭
    edited November -1
    Thanks to all of you for educating me. The lower was registered in WV FWIW but I plan on building a 'rifle' anyway. I'll make sure if it's a 14.7 inch bbl that the flash hider is pinned.

    I remember seeing 7.5 uppers in the auction side and heard warning bells in my head (even though the sellers didn't put any disclaimers in) then.

    Again, appreciate the info very much.
  • Riomouse911Riomouse911 Member Posts: 3,493 ✭✭✭
    edited November -1
    It is easy to pin and weld a barrel, just be careful to not drill too deeply so you penetrate into the rifles bore. True high temp silver soldering is not easy, as regular hobby solder will not suffice under NFA rules.

    I installed a flash hider on the barrel, using a Vortex on a 14.5" BCM upper (because the hider is 2.25 inches long).

    Using a 7/64" cobalt bit and a drill press, I mounted the upper in a padded vise to hold it on the drill press table. I installed the flash hider, then drilled a hole through the flash hider and a little way into the barrel. (From what I understand, in order to be permanent the pin has to be deep enough into the barrel to "damage it" if the flash hider is twisted off. You don't want to be deep enough to hit the bore or make the wall too thin.) Since every barrel has a different diameter, no set distance will work. You have to eyeball it with everything in place for your particular barrel.

    I then used a Harbor Freight el cheapo 7/64" drill bit as the pin. I cut off the bit with a hacksaw and using a bench grinder I made the piece short enough so when it bottomed out it sat just a bit under the surface of the flash hider. You may need a strong magnet to lift the pin out of the hole as you try and re-try the depth because it can fit snugly.

    I taped off the area around the hole and using an arc welder zapped it to weld the pin into place. I then used a file and then sandpaper to smooth out the weld flush with the flash hider, touched it with flat black 2000 degree BBQ spray paint, and voila'! All good with the NFA in under 45 minutes.
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