Perhaps one of our members who collects such source material (old A5 manuals) will stop by and post the necessary reference.

The most recent A5 owners manual I find online under the part about cleaning says the tube should be 'lubricated lightly with an oiled patch'. They were not specific as to the lubricant.

They should have been.

'Oil' covers quite a bit of territory.

One could use 'navy black' and still be in compliance with their instructions. Dog poop would likely void the warranty.

"The price of good shotgunnery is constant practice" - Fred Kimble