Heckler&Koch MR556A1 - Manual (Page 10)

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SECTION 5 — AMMUNITION
By using ammunition with match bullets or other match grade ammunition the MR556A1
will achieve the best level of accuracy. Use ammunition of the appropriate caliber and of
recent manufacture. The MR556A1 is chambered for 5.56 x 45 mm ammunition and will
functioned safely and reliably with most high quality 5.56 mm and Caliber .223 Remington
ammunition.
NOTE: Use only high quality 5.56 x 45 mm NATO or caliber .223 Remington
ammunition in the MR556A1 rifle. Damage caused by the use of improperly assembled
or remanufactured ammunition may void the HK Warranty. Do not use ammunition
assembled with corrosive components (primers, propellants, etc.).
The MR556A1 is designed to use ammunition made to NATO or SAAMI specifications.
DO NOT USE
• Reloads or remanufactured ammunition. Beware of military surplus, foreign or outdated
ammunition.
• Non-jacketed or exposed lead ammunition.
• Corrosive ammunition (primer and/or propellant).
• Empty cases as “dummy“ (inert) rounds, as damage may result. Use complete dummy
rounds available for training purposes.
• Any ammunition that exceeds NATO or SAAMI (Sporting Arms and Ammunition
Manufacturers’ Institute) pressure limits.
• Cartridges that are not 5.56 x 45 mm or Caliber .223.
• Seriously corroded ammunition.
• Dented Cartridges.
• Cartridges with loose bullets.
• Cartridges exposed to extreme heat above 135°F (57°C) until they have cooled.
• Use only authorized ammunition that is manufactured to NATO and SAAMI specs.
• Ammunition that is wet or dirty.
WARNING: Only use ammunition designed to NATO and SAAMI specifications that
is factory-loaded, undamaged, and of the correct caliber. The use of low powered
cartridges could lead to functional stoppages (including bullets stuck in the barrel)
and is not recommended.
Fig. 25
A wide variety of mechanical, optical, and telescopic sights can be installed directly on
the upper MIL-STD-1913 rail (examples, Fig. 25), either on the upper receiver portion of
the rail or on the Free Floating Rail System. For sight alignment and zeroing, follow the
instructions of the sight and scope manufacturers. General mechanical sight alignment
information is depeicted in Fig. 26-27.
NOTE: Do not overtighten scopes, aimers, or any other accessories mounted on any
of the MIL-STD-1913 (Picatinny) rail surfaces of the MR556A1. Overtightening can
damage the rails.
Fig. 26 – Correct Aiming, HK diopter sights (left) and TROY sights (right)
Fig. 27 – Aiming Errors