Mk V2 into wells full metal cqb m406

I’ve had the stock metal gearbox break due to the sorbo pad disintegrating and made the decision to get a MK tactical gearbox as they are locally made and look stronger than a stock one however i found out the original t-piece didn’t fit into the end of the gearbox to line up to a magazine anymore. I did sand back the upper receiver to clear the end of the gearbox but i don’t want to change the outside appearance of the blaster. Wanting to see what parts are needed to finished building this ■■■ and where to get them from as everything i’m seeing are saying “sold out”

1 Like

Welcome @Burgo. Was that a V2 MK box you installed? I’ve just recently finished an M405 and everything lined up so keen to see where the T Piece is sitting as that was one of the more straight forward installs I’ve ever done. You shouldn’t need to change anythign on the outside of the receiver. Got any pics?


Had to grind the corners a little to slip around the lip on the gearbox near the cylinder head

3 Likes

With the magazine in place the t- piece had to sit about three mm inside gearbox housing, not sure to grind the t-piece down to sit inside or grind off so sit just sits flush. Unfortunately I did get some bad info from local shop about replacing barrel (didn’t know the outer barrel won’t accept the 9.5mm Ausgel barrel) so I either have to drill out the outer barrel or replace the t-piece and go back to the wells 9mm barrel just after some thoughts on it! Cheers

I put a retro in mine and went to a 3d printed tpiece and adapter which takes a 9.5mm barrel…

I’ve seen the fighting bro adapters but have been unable to find one for sale at the moment! Might have to invest a good 3D printer the way it is going! What did you do with the outer barrel?


It is a V2 Mk gearbox and the t-piece is only about 2mm from the edge of the magazine well so I think a 3D printed one is the way to go!

Changed to an AAR outer

Rather than change ‘all the things’ complete the build with the stock barrel and t-piece.

Thank you for the information unfortunately I did grind out the original t-piece to fit the 9.5mm barrel but I manage to get another one today so I will be back to stock 9mm barrel although it will be an ausgel one!

Azreals armoury had some fighting bro in stock the other day

Just finished the mk tactical box into my nylon body cqb, now I can’t get it to single shot on semi all I get is full auto. Pull it open 3 times now mechanism seem to be working but as soon as it’s back together full auto, anything I should be looking for

It’s the profile on the selector plate… or the cam on the select switch is not catching the selector plate.