This is going to be a long thread - bitza build - can you guess what it is yet ?

[TonyL]

Awesome! I bow at your feet, sir. Very well done.

[Shed tuner]

Had a look at the power curve today, and frankly it looks like I got lucky with my semi-informed estimates on valve return spring selection/strength, port sizes, hammer spring, etc...

After some basic tweaks, here's the power curve with a max 200 BAR fill.

Shot - power
01 - 10.8
06 - 11.0
11 - 11.0
16 - 11.2
21 - 11.2
26 - 11.2
31 - 11.5
36 - 11.7
41 - 11.5
46 - 11.4
51 - 11.3
56 - 11.0
61 - 11.0
66 - 11.0
71 - 10.7

Knock off the first and last 5, that's 60 shots in the 11.0 - 11.7 range, which is about 17 fps. It's a fairly small cylinder (around 120 CC ?) so very happy with that.
It's pretty much perfectly symetrical, and centred in the middle of the fill, so nothing to adjust there

I've turned the hammer down 1/4 turn, which should result in a max fill of 185/190 bar, and a couple more shots in the sweet spot. If I see evidence of the "peak" on the target at the range, I will have to choke the port down a fraction - it's currently 2.5mm, so 2.2 or 2.3 should do it. there's a couple of ways to acheive it on this gun.

Stock inletting is done, just needs a bit of sanding and tidying up, and drilling for the main action screw - currently waiting for the glue to dry as I had to bung the pre-existing hole as it was half-a-hole out, before redrilling. And a I need a trigger guard, then I can take it to the range !

[les allam]

Nicely done Sir
And a very useful and consistent shot count .
Looking forward to the finished product.
Les..

P S
Please bring it with you to the May Boinger Bash (if you’re going)👍.

[Shed tuner]

It's so close, I can taste it....




As is often the way with things, a lot of the remaining small jobs are going to take some time, including making a trigger guard, rear barrel support, and finishing the stock. But at least I can take it to the range now !

[TonyL]

Fantastic work, Jon. You should be very happy and proud with this achievement.