5.56 short range

I have the CD of the 5.56 book by Ron c Fuchs, but I am struggling to ID a round. The headstamp is HP .223 5.56 with a red p/a brass primer and 3xprimer stab crimps, Brass case. It has a very short black plastic bullet with a GM collar. (length=11.99mm wt= 7.4gr) The book shows two phots of this round and I can not tell the difference between the two photos. For the Experimental round it says " Xpmtl rnd for “blow back” actions, case has rebated rim" If anyone has this round could they please put up a photo of it next to a standard rim…thanks Paul.

Paul, can you check the rim diameter of your cartridge? The rebated rim variant made by HP measures approx. 9.10 mm.

Regards,

Fede

Please see the photo, I am away for a week now so might not be able to respond until I return. Thanks Paul.

Paul, thanks for the photo. It is the variant having a regular 5.56x45 case.

Regards,

Fede

many thanks Fede…