The gun was built as a semi with a post sample bolt.
Now, I'm no lawyer, and I'm not an SOT, but this sounds to me like there's a problem. As I understand it, a "registered post-sample bolt" would be legally considered a "machinegun conversion kit" by the ATF, and therefore a machinegun (hence why it is "registered"). Correct?
Here's the rub: when you install that bolt, i.e, conversion kit in your semi 1919, then the semi 1919 becomes married to that bolt under the ATF's "once a machinegun, always a machinegun" interpretation (remember, the RSP is what's considered the firearm). It would be the same as installing a registered M2 conversion kit into an M1 Carbine. If you were to remove that bolt, the "originally semi-auto" sideplate would still be considered a machinegun by the ATF (under the "once a machinegun always a machinegun" doctine), and you would NOT be able to sell it later as a semi-auto.
Just like if you were to remove that M2 conversion kit from the carbine. The ATF would still consider the M1 a machinegun, it would be "married" to that conversion kit, and you couldn't later sell the M1 as just a semi (even if the conversion kit were removed). At least, that's how I interpret the laws, ATF letters, and the ATF's f-ed up policies. I could be completely wrong here, and perhaps you can cite the section of law that says otherwise.
But what really frightens me, is the fact that you have legally registered a full-auto bolt that will fit into a semi 1919. IMHO, this puts all semi 1919's at risk because one of the only reasons they were ever "approved" in the first place is that the "denial island" on the semi RSP prevents the insertion of full-auto internals. I mean, you obviously have all the legal stuff for class III and all that. If you can register a post-sample bolt, you could have just as easily registered an entire post-sample sideplate. By mixing your post sample stuff with the legally fragile semi stuff, I believe you have inadvertently put our entire hobby at undue risk.
Basically, what I'm saying is that by the mere existence of the conversion parts, nay, just the knowledge that it is possible to convert a semi 1919 to full auto with just some machine work to a full-auto bolt to clear the denial island, would be more than enough ammo for the ATF to have a "reinterpretation" of the laws and decide that 1919s are no longer legal enough for them. This could cause all of our guns to be deemed illegal overnight, a-la the Akins Accelerator.
I was kind of afraid that something like this might eventually happen. I was just afraid to open my mouth about it for fear it might give someone an idea, therefore becoming a self-fulfilling prophecy.