Just announced late last week is a contract with Speer for a new 147gr load to accompany CBP's transition to the Glock. The new bullet is the Speer G2SR. I haven't seen any of the ammo yet (and likely won't for some time) but it is rumored to be a nickle plated case and a black oxide bullet. I believe this was done as a way to allow easy visual verification that duty ammo is being load/used vs training ammo. In years past CBP used Federal XM40 that was basically Federal HST without the nickle plated case. Training ammo was a Winchester 180gr FMJ with a purple stain to denote that it was training use only. Aside from that possibility, there could be some corrosion/tarnish benefit to the black coating.
Anyway, ammo testing was conducted by NIJ Labs with the following results:
SPEER 147gr G2SR
Muzzle Velocity 913 FPS (no note of barrel length)
Bare Gel: 14.4 .654 expansion 100% retained weight
Heavy Clothing: 15.9 .623 expansion 100% retained weight
Steel: 14.8 .507 expansion 100% retained weight
Auto Glass: 14.7 .465 expansion 78% retained weight (114.4 gr)
The current loads being used for the Glock transition are a Speer 124gr Gold Dot +P and a Winchester 147gr Ranger. These loads will continue to be used until the new Speer comes online in 2021.