How many AR lowers can you buy in a period of time before the ATF says "Hi"

[FromMyColdDeadHand]

Not looking to stock up, but I sold a lower recently and I already had an extra upper and I'm looking to add a couple KISS uppers over the winter so I thought I might get in four of the blemished Bravo lowers. Wasn't there a change recently (last year) about lowers being transferred more like pistols than like rifles on 4473s? Is there a magic number of lowers that triggers mandatory FFL notification to the ATF? Is there an unnofficial number that might peak the ATFs interest next time they peruse my FFLs books?

[Elhuero]

I hope an batfe agent stubs his or her toe on something really, really hard right .... now.

[FromMyColdDeadHand]

I'm done with expensive ARs and I wanted to save on shipping and transfers. I want to build some BCM uppers, one to run a 22lr conversion kit and another as a lightweight Kiss rifle. One with the Midlength MOE hand guards and another with a Dissy set-up and the to-be released Rifle MOE guards. Just don't want the ATF stopping by and me having to explain to my wife why I bought 'so many guns". I've been a good boy this year, these would be my first 4473s this year.

[sniper7]

They don't transfer as either a rifle or a pistol now. I have bought several lowers at once and never heard anything. If if did, i would simply tell them i am using them for legal purposes and there is no restriction on the number of guns i can own let alone stripped lower receivers that aren't even functional without a lot more parts ns money.

[BPTactical]

I believe the BATF changed the classification to "Other Firearm" for stripped lowers and pistol grip shotguns. I also believe that complete lowers may fall into the same category but don't recall for sure.
The biggest change to the purchaser this caused is you now have to be 21 to purchase a "Other Firearm".
I don't know if purchasing multiple lowers at one time is required to be treated as "Multiple Handgun Purchases" since the above change and documented on a separate record.

Good question.

[FromMyColdDeadHand]

I believe the BATF changed the classification to "Other Firearm" for stripped lowers and pistol grip shotguns. I also believe that complete lowers may fall into the same category but don't recall for sure.
The biggest change to the purchaser this caused is you now have to be 21 to purchase a "Other Firearm".
I don't know if purchasing multiple lowers at one time is required to be treated as "Multiple Handgun Purchases" since the above change and documented on a separate record.

Good question.

I knew the 21 age thing, so that had me thinking "pistol", thanks BP and Sniper for the clarification.