KG 99 vs Tec 9

[Jackspack]

so I have this KG-99 built by Interdynamic in the 80s. I see some of them are $700-$800 now on Gunbroker but several of them are $1900+. What am I missing on the variant that would make the difference.

Pics of mine are listed.

I was told this one was originally a version that went back to INterdynamic for an "upgrade" to make it NFA compliant

 

[letusbuyyourcar]

NOT an expert here but the KG99 I believe was the semi only version of the open bolt KG9 SMG built by Interdynamics. They didn't have any real success finding military/law enforcement contracts for the SMG version. I ASSUME some of the early KG99 models were open bolt semi only pistols kinda like the open bolt semi Macs from the early 80s. I have seen just the bolt from a KG9 for sale on Gunbroker a good while back. Seems like it was over $5,000. So I assumed that was the registered NFA part in that design. Not sure though.
As far as yours I think the only difference in value or say "Collector Value" would be the brand name molded into the frame. I assume Intrdynamics is way more sought after than Intratec. And that's really only due to the scarce nature of them.
I' in for answers here and better info than mine. I like the ugly guns from the 70s/80s that you don't see much anymore. I would like to find an Encom in 9mm or 45ACP. They were built in Atlanta and looked like someone was building them in a garage with steel pipe and a welder. I also dig the Kimmel AP 9 that was basically just a better designed Tec9. I'd like to see someone adapt an M4 stock onto a Tec or AP9 for an SBR setup.

 

[GAgunLAWbooklet]

Is there any difference between a KG-9 and a KG 99? ATF ruled in 1982 that the Open bolt Kg-9 was too easy to convert to full auto, so all the ones made after Jan. 19, 1982 are NFA weapons. The ones made prior are grandfathered and treated as non-NFA weapons IF you don't modify them.

 

[corvo]

you still have yours?