Model 1871 Preußen Foot Artillery
 
Model 1871 Preußen Fuß Artillerie Mannschaft (Other Ranks) Pickelhaube. This helmet was used by 1st, 2nd, 3rd, and 6th Fußartillerie Regiments.

The helmet is marked "PI AR 1870" on the rear visor but it is very difficult to make out.

The date, plus the very high profile of the helmet, indicate that this was possibly an M1860 helmet, cut down and re-issued as a M1871.
 
A view of the M1871 front plate for the 1st, 2nd and 3rd Fußartillerie Regiments. The FWR cypher was unique to these three regiments of the foot artillery.
A view of the rear showing the plain rear spine and huge rear visor, typical for an early helmet.
The liner is made from the typical heavy-grade leather.
A side view showing the high dome of the helmet.