Legality of single shot open bolt rifle

[bbguns44]

If a single shot rifle is made from a Sten parts kit, no mag cut out
in the tube receiver, using the original parts ( open bolt design ),
is it legal ? What are the rules on single shot rifles & pistols ?
Thanks.

[AJAX22]

in theory it should be legal (I've heard of people doing it)

however, send in a letter to the batfe to get approval first.

[ke6guj]

I've heard of BATFE saying it was an MG, even as a single-shot, since someone could add a magazine well to it and have an MG. Falls under that umbrella "5-hours in a machine shop" BS or whatever the timeframe is.

I'd definitely get a ruling on it first.