6.5 Grendel barrel Length?????

[lazyengineer]

When applying the BATFE letter regarding the TC Contender to AR15 stripped lowers, those lowers purchased as "pistols" or "firearms" can be configured as pistols, rifles, and converted between the two. However, if you have an AR15 that you bought as a complete rifle, the lower receiver on that firearm is a rifle and cannot be legally converted to a pistol setup without violating the NFA. You can build out a stripped lower into a rifle, then later convert it to a pistol, without violating the NFA per the TC Contender letter here: https://www.atf.gov/firearms/docs/ruling...s/download
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Might want to read that letter again. First paragraph in italics is clear. Converting a pistol via attaching parts (in our example an upper), that make it into a rifle, is not making a new firearm. Converting a rifle that was originally intended to be a rifle, into a pistol, IS making a new firearm.