I own several Class III items. Each of them requires a separate form 4 (2 copies) for each transfer of the class III item.
I.E. If you want two sound suppressors, one a 9mm Luger and the other a .45 ACP suppressor you will have to have two set's of form 4's per each suppressor. $200 submitted for the ATF Tax stamp for both ($400) and each set of form 4's has to be signed by the local Chief of Law Enforcement or use a trust as described in the article above. Finger prints on both set's of forms and a passport type photo on both set's of forms.
Your Class III dealer submits these too an examiner at the BATFE and your required background check is then completed. Your dealer will recieve the copy of the approved form 4 and allow you to transfer the item into your hands at that time.
"When a government robs Peter to pay Paul it will alway's have the support of Paul" George Bernard Shaw