High Precision(down) Range HPR 165gr HBFP Pull-Down

[The_Shadow]

Cartridge is from Ammo Manufacture: High Precision(down) Range HPR 165gr  HBFP
Ballistics Information: 10mm Auto
Muzzle Velocity: 1265 fps
Muzzle Energy: 586 ft. lbs
Brass Make/Headstamp: HPR - Brass
Bullet Make/Weight/Construction/Info; Length 0.6120"/Dia. 0.4000":  165gr. HBFP FMJ
Actual weigh 165.6 grains  Crimp Diameter 0.3980" 
Meplat 0.2310" / Hollow Base 0.2615" / Inside Dia. 0.1800"
C.O.A.L.: 1.2585" / 1.2595"
Primer: Nickel color
Case: Diameter 0.4215" Crimp Diameter 0.4200" Length 0.9875"
Powder Description/Positive ID/Type/Charge Weight: ? AutoComp ?  8.4 grains
Test Velocity: 1286, 1255, 1257, 1260, 1268. Average = 1265.2/587 LBS

[Intercooler]

Odd bullet with the hollow base 

[The_Shadow]

It maybe a plated bullet from and adjustable die, using the base fill for weight changes, deep hollow base for light weight and shallow to no hollow base for heavier weights.  The advantage is longer bearing surface for consistency and  better accuracy.