Source: https://en.wikipedia.org/wiki/Schwerer_Gustav

Type	Railway Gun
Place of origin	Nazi Germany
Service history
In service	1941–45
Used by	Wehrmacht
Wars	World War II
Production history
Designer	Krupp
Designed	1934
Manufacturer	Krupp
Unit cost	7 million Reichsmark
Produced	1941
No. built	2
Specifications
Weight	1,350 tonnes (1,490 short tons; 1,330 long tons)
Length	47.3 metres (155 ft 2 in)
Barrel length	32.5 metres (106 ft 8 in) L/40.6
Width	7.1 metres (23 ft 4 in)
Height	11.6 metres (38 ft 1 in)
Crew	250 to assemble the gun in 3 days (54 hours), 2,500 to lay track and dig embankments. 2 Flak battalions to protect the gun from air attack.
Caliber	80 centimetres (31 in)
Elevation	Max of 48°
Rate of fire	1 round every 30 to 45 minutes or typically 14 rounds a day
Muzzle velocity	820 m/s (2,700 ft/s) (HE) 720 m/s (2,400 ft/s) (AP)
Effective firing range	about 39,000 metres (43,000 yd)
Maximum firing range	47,000 metres (51,000 yd) (HE) 38,000 metres (42,000 yd) (AP)

When building the interior of the gun, (the ammunition storage and shell/propellant elevator), I had no real sources to go off and no real idea what it looked like, so I just went with the flow and made it how I thought it would look like. Although it certainly isn't the best Gustav, It is still the work I am most proud of. I tried to make it look as 1:1 as possible but I'm certainly not the best.

Any feedback on how I can make future projects better would be much appreciated!

If you want to use the schematic, I would appreciate it if I was creditted.