5.56mm MK255 RRLP and XM1037 SRT

I’m trying to track down information about the MK255 RRLP (Reduced Range Limited Penetration) frangible 5.56mm ammunition reportedly used by SOCOM and the FBI, for both training and short-range (urban) combat use. There was a DTIC presentation on it in 2006: kim.pdf (191.4 KB)

I have come across two different DODIC numbers for this: AA40 (which seems to relate to the Mod 0) and AA17 (which seems to be the Mod 1). Can anyone confirm this, and explain the differences between the Mod 0 and Mod 1?

The bullet is jacketed with a frangible copper/polymer matrix core. The pics I’ve seen shows a rather blunt, grey-painted tip.

I know Black Hills has made this ammo, but has anyone else? And is it still being made and used?

This thread provides some information as well as lots of pics of the ammo and its boxes: calguns.net/calgunforum/show … p?t=891433

Secondly, does anyone know if the 5.56mm XM1037 Short Range Training ammo, which uses a fluted bullet and was expected to enter production in 2010, has actually entered service?

Many thanks for any help.

From left to right:
FC/S/89 (or 68?) Short Range M862
LC/69 Dummy M232 Sand and Silicone Filled, chemical blackened case
LC/69 Dummy M199, 6 Corrugations
FC/? Frangible Purple Tip AA40?, MK255 MOD 0, 50gr
WCC/05 Frangible Gray Tip AA17?, MK255 MOD 1, 62gr (5.56 RRLP)
LC/01 Optimized Brown Tip, 70 gr Barnes TSX
Hope this helps, kevin

Many thanks for that, very interesting!

I thought I had a grip on the Frang codes in 5.56 till I came across this ammo can at an army surplus store. It lists the AA40 as now being Mk311

I might have known - try to clarify something and it gets more complicated!

I don’t suppose anyone has catalogued all of the US M and MK numbers which apply to small-arms ammo…? Could be a useful project if not.

There’s that list of M, XM, PGU and Mk numbers from the 1960’s Frankford Arsenal manual. That’s been found on a couple places out on the internet.

PEO Ammunition Systems Portfolio Book 2012-2013 can be downloaded from www.dtic.mil as AD-A567897

It does not answer the question of AA40, but anyway is an authentic list.

Thanks guys, much appreciated.