New 07/02, working on making a DIAS.  I emailed the ATF asking what information needed to be engraved on the DIAS; the response was:

"The marking requirements remain the same for sears.  However, FTB may
authorize alternate means of identifying such parts upon receipt of the manufacturer’s letter
application showing that such other identification is reasonable and will not hinder the effective
administration of the regulations."

I followed up specifically asking whether it needed caliber markings, but have not received a response.  For those of you with a DIAS, does it have caliber markings?  Obviously real estate is at a premium, there's just not much room for engraving, and a DIAS by itself has no caliber.

I did not caliber mark my DIASes, and marked their registration forms N/A in the caliber/bore box. Same for barrel length: N/A.

The DIAS is a machinegun conversion, which has no more intrinsic caliber than does a machinegun receiver with no upper/barrel attached.

If the device you are registering has an intrinsic caliber or barrel length, then you must include those, but that is not the case for a DIAS.

Thanks.  That's what makes sense to me, but that doesn't mean anything when the ATF is involved.

I'm interested in the response. As an 07/02 I'm all ears...

As a gun writer, I can see a number of articles arising from this.

FWIW, it's done now.  I was required to have a model and SN, but nothing else.  I turned in the eform without a model, and had it bounced back within 24 hours.  Obviously the part also had to have my company name and location engraved.

All DIASs I've seen, both transferable and post sample have all not had calibers engraved on them.  Doesn't mean it's right, but atleast that lets you know what ~10 diass look like.  All the forms I've seen list the caliber as "N/A" as well.

Exactly, no different than how you would mark a F/A receiver.