Transfer port upgrade to different size

In this instruction, I'll show how to replace transfer port.

This is instruction for an item sold by me on Etsy

High flow transfer port

High flow transfer port offers higher air flow than original one (original transfer port is 3,5mm or sometimes 2,5mm).

Disassembly

Remove grip by unscrewing one bolt.

Slide out stock.

Remove bolt holding hammer spring cap.

Remove hammer spring cap and hammer spring.

Unscrew barrel band and slide it away from down tube.

Move bolt handle to back position.

Remove pellet single shoot tray (or magazine).

Unscrew bolt which holds block and down tube together.

Replacing transfer port

Remove transfer port with 2 orings.

Replace transfer port with 2 orings. Left one is in factory size 3,5mm. Right one is 4mm.

Drilling

When you change transfer port from 2,5mm to bigger one then you will gain some power.
When you already have 3,5mm transfer port then to achieve full power gain you need to drill the barrel port and valve port to a bigger size.

I plan to drill it to bigger size in the future, after some more experiments.

Assembly

It should be easy, you need to make it in opposite order. There is only one important step.
Before connecting block to down tube, make sure that hammer is in back position and bolt handle is in 2/3 position.

After connecting the block with down tube, make sure you can move the bolt handle to back position. Like in the photo.

Install barrel band again.

Install hammer and hammer spring.

Install handle.