Machining of the breach end of the barrel

[Gudge]

Hi, I could do with some advice.
I have a Rapid Mk1 at 12 ft lbs and the breach end of the barrel has been butchered in many ways at some  point in the past.  So I am looking to take half an inch or so off the end and re-machine all new features.  I have the detail for the porting from this forum, counter drill at 4mm then increment the drill sizes up to 3mm to reduce the burr when machining the port and then de-burr carefully when done.  The rest below is where I am looking for advice as I would rather work to dimensions than measure from a damaged part..

Is the grub screw dimple on the same centreline as the port?
What are the dimensions for the spigot diameter feature at the rear of the barrel where it meets the magazine and also the lengths of these features relative to the port centreline?
Is there anything needed to smooth the entry feature where the pellet enters the barrel?
Does anyone have a dimensioned drawing for this area?
All comments are welcome, and all the best for the season to all on the forum
Gudge

[KevG]

10mm  diameter for the magazine blip and 1mm proud.for porting and location dimple its 5.4 mm from centre of port to barrel shoulder not including magazine blip same for location dimple.
KevG

[Gudge]

Thanks Kev, that is exactly what I needed for the dimensions.  For the barrel entry after shortening do in need to do any more then a light deburr to to help the pellet enter?
Thanks again. Gudge