Good evening:
Ending with the saga of WWI british artillery, the good BL 60 pounder, the british workhorse in counterbattery work:
The first one is a Mk. I in a Mk. I carriage with wooden wheels of sturdy appearence in firing position. The second one is also a Mk I gun, but now in a simplified Mk. II carriage (in Mk. I carriage, the gun in traveling position was moved forward, so the weight was distributed between the gun wheels and the limber. In the simplified Mk. II carriage the gun was in the same position while traveling, so a stronger -and heavier- steel wheels were needed) in towing position, but I don´t know if it is accurate to have the sights in place in the traveling mode. In the second row the modernised Mk. II is depicted. It was almost an entirely new gun, with a longer barrel, the recoil mechanism place under the barrel, and since the 1930s, pneumatic wheels. Carriage Mk IVP was used also for the barrel of the new 4.5 inch gun. The 60 pounder Mk. II was well used (19 guns were lost in France) during the first half of WWII until it was replaced mainly by the 5.5 inch gun. Cheers.