Here is the initial letter from ACE that I posted:
We don't plan on submitting the M4 SOCOM to the ATF for approval. Depending on the examiner that we get depends on whether it would be approved or not. If the ATF says not approved to us, there would be no "wiggle room" for anyone else to install it on a post ban weapons. For example we sent in the AR boom Tube stock and were denied approval. At least one other individual sent in his ARBT and it was approved for post ban use.
Cordially,
Bob & ACE
I emailed him after this and asked him to clarify "wiggle room", this is the response:
I believe you still could be arrested for it and that your rifle could be confiscated and a search warrant could easily be obtained for searching for other illegal weapons. What I meant to say is that it wouldn't be wise to install an M4 SC on a post ban weapon with out ATF approval.
Cordially,
Bob & ACE
Sounds a bit different than the first letter huh? Oh well, I wouldn't be too worried, from the little I know, it fits post ban specs when the bolt is tightened; if you were worried about it, you could just have it spot welded in place too and it would be totally legal.
Heres a pic of an Ace M4 (not mine)
[img]http://www.imagestation.com/picture/sraid87/p4c287da89aa89625c338f5b057dbdb6d/faa0f28d.jpg[/img]
Good Luck.