Airguns vs powder guns and the lands

[Barzor]

So been having issues with my pp700sa with new 16 inch barrel. It does not sit flush against breech because that piece that goes between just spins around. SEE PIC

So it got me thinking. Basically with this bit of a gap I have given it a throat. In powder guns the bullet should not be driven into the lands but in airguns we are. If I load my pp700sa now the pellet head is into the lands a bit while a bit of the skirt is out. Won’t this give me more velocity as there is more air now in that area. The big question will this affect accuracy???

I’m planning to find a way to screw in my barrel at same time holding that breech piece so it doesn’t spin but I’m just wondering about this.

 

[CrashKT]

Short answer, No.

 

[Teep]

Actually .22 long rifle match barrels have the rifling cut close so the bullet engages the rifling.

 

[Barzor]

Short answer, No.

Just to clarify the whole pellet has to be in the barrel. The back part for the pellet skirt has to be flush with the barrel end.

 

[Barzor]

Does anybody know the drill size and tap to put a set screw? I want to make sure it a common size screw I can use? Finally where do I drill on the reciever. Any pics?

 

[marflow 777]

set screw could be 3mm but no bigger than 4mm +
Diana Chasers uses 2-4mm x 2mm and the center on is 4mm x 3mm to hold their barrels in the breech
now i state mm because i try very hard to keep metric in metric and inch in inch

do i assume that the collar that the barrel threads into can be removed from the rear of the breech and the Oring that is on the collar i the seal
if the collar is net, net one small set screw from the top would work but as you drill through there will be a burr on the inside that might or might not be removed by the process of tapping the hole
i would not do the job without a drill press and an automatic center punch would be handy
and how much of the pistol's disassembly is unknown to me but it would be a lot

a factory looking job would be your goal and why it was never done is stupid manufacturing

now if the breech collar could stay in place and not be an issue if it did not come out, epoxy could be your friend but much care would be needed

just some idea about something i know nothing about
https://spares.bagnallandkirkwood.co.uk/wp-content/uploads/2017/07/PI7-Exploded-Diagram.pdf