Semi auto 12g from S2 to S1 and back?

[gixer1]

A sec 1 will not be granted for wildfowling

It doesn’t need to be - the section 1 usage would be steel plate, when the magazine is changed to a 2+1 it would no longer be section 1…

 

[reiver]

It doesn’t need to be - the section 1 usage would be steel plate, when the magazine is changed to a 2+1 it would no longer be section 1…

Are you wanting to swap magazines over often ? Just even if you put a 2 shot tube on a sec 1 it is still a sec1 until you get it deregulated to sec 2 . Then you would probably need a variation to switch back to fac .
Probably better to just buy another gun .
You can also use slugs in a sec 2 gun just have it stated on your fac with the slugs

 

[Loler UK]

Fine in theory, except that the majority of semi automatics are designed with a magazine tube for 4 cartridges. It’s why for the UK market they need a crimping grove, or some other non removable watchamycallit 1/2 way along to stop them taking more than 2 shells.

In the US when shooting waterfowl you can get away with a wooden plug inserted into the tube, but in the UK it has to be a permanent modification that cannot be easily removed.

A plug has never been tested in the UK courts. I'm not suggesting you be the test case but the law doesn't stipulate s1/s2 or that the restriction needs to be permanent.
This has been agreed (use of temp mag restrictions) for schedule 6 quarry by certain forces & interested parties / stakeholders. Sadly I can't give more specific details but you can fill in the blanks.

 

[Heym SR20]

A plug has never been tested in the UK courts. I'm not suggesting you be the test case but the law doesn't stipulate s1/s2 or that the restriction needs to be permanent.
This has been agreed (use of temp mag restrictions) for schedule 6 quarry by certain forces & interested parties / stakeholders. Sadly I can't give more specific details but you can fill in the blanks.

The words used in the definition of a shotgun are

either has no magazine or has a non-detachable magazine incapable of holding more than two cartridges;

The key word is “incapable”

In other words, there should be no way, other than major alteration by a gunsmith, that the average user can load more that two cartridges in the magazine.

A wooden plug is easily removed by the shooter so I would falls outside the definition.

 

[Reloader708]

Put me right if I'm wrong but can you even convert the A400, I have one (three shot) and there's nowhere for the mag tube to extend to.

I've had a look at my gun, apologies, its an A300 and I'll stand by my original post and say I can't see any way to fit an extended mag tube to this model. Perhaps so the A400 however.