I was offered a BCG, the man who offered it said he forgot who made it but that it was the company that built them for DD. This threw me a bit as I was under the impression that DD made their own BCG? Is/are there any distinguishing marks to look for?
Not to cause you a headache, but there are some early ones that were not marked. I have an early, factory assembled M4V1 and the BCG is not marked. They started the DD logo after initial production: