Germany

Firearms have to be unloaded, no ammunition in either the chamber or the inserted magazine.
Firearms have to be in a container either not accessible within 3 steps or locked.

Ammunition can be transpored any way, loaded magazines are allowed. Ammo has to be separate from the firearm. This is still the case with loaded magazines in a bag inside the riflecase for example.

While not at a permanent residence, firearms and ammo must be stored by taking necessary precautions to prevent their loss or unauthorized use. Firearms and ammo can be stored in any locked container. Essential parts can be taken out of the firearm, like barrel from a pistol or bolt from a rifle. This piece can be carried on person or locked away. The firearm can be temporarily stored in a car. Anything reasonable to prevent loss is fine under this rule.

• Fully automatic firearms
• Pump Action Shotguns
  • less than 95cm long
  • or with a barrellength less than 45cm
  • or with only pistol grip (no stock, pistolgrip shoulder stock is fine)
  • Pumpaction Shotguns with none of these features are allowed
• concealed firearms (shooting pen)
• multishot short firearms (<60cm) built after 01.01.1970 with a centerfire caliber below 6,3mm (basically banning 5.7x28mm fireams like P90 or FiveSeven Pistol) But this also bans AK74U and similar
• All Military ammo like tracer, AP, green tip (Military ammo without special bullets like M193 are allowed
• Civilian Tracer and AP ammo

Only german exemtions apply, no recognition of foreign exemptions for sport shooters and hunter.

• Standard-size Magazines (>10 rounds) for rifles / >20 Rounds for short firearms)
  Be careful, if a pistolmagazine fits in a rifle in your possession it is assumed to be for rifles an therefore can not exceed 10 round capacity
• Lights and Laser modules built for firearms
• Nightvision sights built for firearms

Only german exemtions apply.
Although possession of banned magazines is neither a crime nor a offence, it is unclear if transit with the magazines is allowed.
Light/Laser, Nightvision sights are a criminal offence.

No.

There is no clear cutoff. But should in practice not exceed more than 2 weeks after last day of the invite.

Firearms that are used in sport shooting have the following restrictions.

• No Handguns with a barrel length of less than 7.62 centimetres (three inches)
• No Semi-automatic long firearms with a magazine that have a capacity of more than ten cartridges
• No semi-automatic firearms which by their external shape give the appearance of a fully automatic weapon of war (after 1945) , if
  • the barrel length is less than 40 centimeters,
  • the magazine is located behind the trigger unit (bul-pup weapons)
  • the case length of the ammunition used for long guns is less than 40 millimeters

Basically short AR15s, PCC that look like Submachineguns, and AK47 type weapons are banned from sport shooting. The exemption from this Ban is if the handguard is completely closed (no vent holes, MLOK, KeyMod) although usually a decision from the Bundeskriminalamt is necessary for compliance. If you want to do sportshooting in Germany with a firearm like this, send a picture to the organizer and ask if the firearm would be compliant.

These are not banned weapons but they are banned from sport shooting use in Germany. So transit with them is fine. However if you compete in germany your firearms have to comply.