Trim it down to what is most relevant - you are a long term collector of Transformers who wishes to procure MP-36 for his Masterpiece collection as Megatron is a primary figure.
There is no exemption made for replica firearms being imported for having an orange cap that I am aware of. There certainty wasn't 10 years ago when MP-5 was released.
I'd hazard that they probably won't respond to a letter like that unless it's a generic response.
If you order MP-36 and it is seized, you will need a relevant license to have it released.
If it's the one I'm thinking of, I wrote it.There would have been a part about MP-5 being oversized, which isn't applicable to MP-36, but if you have the license that should be all you need.