MitchWerbellsGhost87
UZI Talk Life Member

I seem to recall that we have at least one former employee of RPB industries here on the board. I’m hoping maybe someone who was involved in the original 1978-82 operation can chime in here and share some knowledge regarding this stamp.
The stamp in question is the letter “R” with a Cobray symbol and “MAC x” (x = a number) inside the letter R. I have speculated that the “R” is likely for “RPB”, being as I have seen this stamp on various RPB parts now, including the bottom of the front trunnion on many of the carbine upper receivers, M10/45 30rd mags, and on the receiver reinforcement tab in an SSM11 single shot pistol (I did not see this one personally but a fellow collector has).
I have a friend who is close with Wayne Daniel so I had him inquire about it, but Wayne is in his 80s now and certainly doesn’t recall every little detail from 50 years ago, so he didn’t have much input on that stamp. I think he was under the impression that my buddy was asking him what the magazine itself was, not the stamp, as he simply said it was a grease gun mag that was done by MAC.
I initially thought it may have been a MAC thing, being as it has “MAC” on it, and the stamp may have originally been something RPB acquired through the MAC auction, but at this point I can confidently say I have only seen it on gun parts that were at the very least assembled by RPB. That said, it is totally possible that the R stamped parts were leftovers from the MAC era… but given the fact that they seem to be almost exclusively present on the bottom of the RPB carbine uppers, I have my doubts about them being done by MAC (at least the items I’ve seen bearing the stamp).
I have been told that it might stand for “reject” but that just doesn’t seem to be the case. None of the items I have seen with this stamp have had any issues or shown any indications of being a reject or factory second, and if they were “rejects” then why would they complete them and then let them get out onto the market?
I personally suspect that RPB was stamping the bottom of the carbine uppers with this logo because those uppers were sold on their own as aftermarket upgrade parts. I would love to have a positive answer on this mystery but I fear that may never happen with so much time having passed and very little having been documented about this stuff.
Oh and to add to the mystery, I recently acquired an RPB M10/9mm carbine upper receiver that has the letter “P” stamped on the bottom of the trunnion, but no Cobray or “MAC”… the plot thickens ¯\_(ツ)_/¯

The stamp in question is the letter “R” with a Cobray symbol and “MAC x” (x = a number) inside the letter R. I have speculated that the “R” is likely for “RPB”, being as I have seen this stamp on various RPB parts now, including the bottom of the front trunnion on many of the carbine upper receivers, M10/45 30rd mags, and on the receiver reinforcement tab in an SSM11 single shot pistol (I did not see this one personally but a fellow collector has).
I have a friend who is close with Wayne Daniel so I had him inquire about it, but Wayne is in his 80s now and certainly doesn’t recall every little detail from 50 years ago, so he didn’t have much input on that stamp. I think he was under the impression that my buddy was asking him what the magazine itself was, not the stamp, as he simply said it was a grease gun mag that was done by MAC.
I initially thought it may have been a MAC thing, being as it has “MAC” on it, and the stamp may have originally been something RPB acquired through the MAC auction, but at this point I can confidently say I have only seen it on gun parts that were at the very least assembled by RPB. That said, it is totally possible that the R stamped parts were leftovers from the MAC era… but given the fact that they seem to be almost exclusively present on the bottom of the RPB carbine uppers, I have my doubts about them being done by MAC (at least the items I’ve seen bearing the stamp).
I have been told that it might stand for “reject” but that just doesn’t seem to be the case. None of the items I have seen with this stamp have had any issues or shown any indications of being a reject or factory second, and if they were “rejects” then why would they complete them and then let them get out onto the market?
I personally suspect that RPB was stamping the bottom of the carbine uppers with this logo because those uppers were sold on their own as aftermarket upgrade parts. I would love to have a positive answer on this mystery but I fear that may never happen with so much time having passed and very little having been documented about this stuff.
Oh and to add to the mystery, I recently acquired an RPB M10/9mm carbine upper receiver that has the letter “P” stamped on the bottom of the trunnion, but no Cobray or “MAC”… the plot thickens ¯\_(ツ)_/¯

Last edited: