Much in the same way a NFA weapons are exempt from 922r, would an SBR be exempt from the closed-bolt requirement?

This came up in a discussion earlier and inquiring minds want to know.

I don't think so. The reason for the open-bolt semi ban was that they were too easy to convert to full auto.

Open-bolt guns made after 1980-something are all considered MGs.

Kharn

No.

Mike

It was last challenged interpreted in 1983, (July 25, 1983 date of final ruling) Jersey Arms Works, Inc. v. Secertary of Treasury, No. 83-1130 (D.N.J. July 25, 1983)

It references heavily ATF rulings 82-2 and 82-8 Found Here

No open bolts allowed.

Joat

If you want to get technical, there is no "no open bolts allowed" ruling from ATF.  The ruling you posted only addresses a few specific guns.  Namely the KG-9, the SM10, SM11-A1, SAC, and the YAC Sten MK II.  It only relates to theses specific guns.

There is no law or ruling stating that you cannot design and build a new open-bolt semi-auto firearm.  But there is a good chance that ATF would deem that design a MG.  But until they look at it and make a ruling, it's not considered a MG.  

Most people don't feel like taking the chance.

I saw a letter from a year or two ago stating that registered SBR did have to comply with the USA parts compliance nonsense.  If anyone has seen something different since then, would like to hear about it.

I read the rulings as a de facto ruling on the  subject.  Kind of an "asked and answered" situation.  Not once, not twice, but three times they have ruled that a semi auto cannot fire from an open bolt, due to the ease of conversion inherent to the design.

I am sure that someone could design a firearm that uses an open bolt design and avoids all the pitfalls that lead to MG status.  I do agree with you, Garrett, that its probably not worth the risk/expense/trouble to do so.

Joat