So starting at the top:
Front and rear flip-up Magpul open sights. The standard BR99 rear sight is fitted to an AR type carry handle and I really did not like it, now this sounds like a bad start, first paragraph and I am criticising the BR99 however I am not as I really do like these, it is just that I could not get on with them, the Magpul offerings have transformed the sight picture and cheek weld is also perfect for both myself and the owner.

Moving forward is a breaching choke complete with very pointy teeth on the end, I did offer to machine them back however this was greeted with a scowl. No doubt such an item would be banned in Scotland for being pointy..
The front end has been changed to an aluminium unit with forward charging handle. This item comes with a new lightweight piston and top Picatinny rail. The item is superbly made however it did not fit… well it nearly did however it took an hours work to sort out the internals so it could be fitted, it was not the end of the world and is a huge improvement as you effectively have a forward assist that can be operated with the left hand. The manufacturers are aware of this issue and the new ones will be built with the necessary clearance. If it was not for this minor issue all of the listed modifications could have been fitted in under an hour.
Moving down is a new oversize magazine release catch and an enlarged bolt handle and sitting on the left hand side is an extended bolt release catch so the BR99 bolt can be released with one finger from within the trigger guard.
Final modification is 1.1Kgs of Chromite heavy sand in the butt section. To do this find a suitable light plastic bag without holes, remove the rubber butt pad and stuff the bag into the void, now add the Chromite slowly tapping the butt from time to time to settle the sand, once filled tie a knot in the end of the bag and replace the butt pad. This does add some weight however it also moves the centre of balance back and keeps everything quite neutral, a worthwhile and cheap improvement.

The BR99 is becoming a firm favourite of mine and cost wise it is a serious box fed bargain.
Many thanks to DangerMouse for hauling his BR99 over today for me to pull apart and fiddle with and for the photo shoot.
For those of you asking about the 10 shot magazines they are due in right now and only a couple of weeks late… I am starting to learn that anything involving firearms coming into or going out of the UK takes time and patience to allow things to progress properly.