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Could you tell us your source for hammer springs, sounds like the springs may be the key for adjusting FPS, along with port sizes.
Regards
LarryW 🙄
The new .22 bolt O rings are 3mm X 1.5mm N70
A selection of tunable hammer spring kits will be available from Mrod air.
Nice looking setup Wingman, can you tell us the size of the proper metric O-ring for the P-12 bolt probe? Thanks again for sharing all your craftsmanship with us.
Could you tell us your source for hammer springs, sounds like the springs may be the key for adjusting FPS, along with port sizes.
Regards
LarryW 🙄
The BSA barrels are 15.4mm so I got a second set of scope riser mounts from SPA and opened up the clamping sections in them to suit. The std SPA barrels are 15mm.
There is enough grunt in these pups to push cast bullets for sure.. the .25 hits the 1000fps with all the factory springs in place! .30cal and .35 (9mm) would be no problems power wise.. Im unsure the breech will cope with the larger bores though, A custom breech and riser mounts may be necessary.
Wing
39 shots at 68 fpe. Hell ya.
Paul
Thats looking real good… Did them BSA barrels come standard at a .590 OD? That is the size of the factory P12 correct?
I have about 8 tins of .25 and no gun to shoot them so the 2nd P12 i was thinking .25 or .257….
sounds like that P12 has the potential to sling some lead… plus its got that TI tube so we could push it up higher on the Fill. .257 does sound nice. after reading your last comment about it slinging the JSBs at 1100 makes me want that .257 real bad
can’t wait to get mine.
Here’s the care package From SPA:
With a bit of machine work and a new BSA .25cal barrel I now have this prototype up and running.
I need to do loads more testing be fore Im happy it is the best it can be, but to give you an Idea of the results I have so far: the max velocity it can push a JSB 25.4gr king is 1100fps, it is currently shooting 39 shots from 220bar to 120 bar at 910fps with the Huma reg fitted. At this tune its shooting thumbnail sized groups at 50 yards..
Surprisingly there is very little difference in sound between the .25 and .22 cal.
It was good to see a few changes in the parts that arrived, such as the duel O rings on the probe with the correct groove tolerances to fit a std sized metric O ring and also the serrations machined off the cocking cap screw:
Well done SPA!
Textured coating:
You’ve got my attention Matt! :8:
KnifeMaker
NIce looking thumper there, Kiwi! Is the stock synthetic or is that a coating?
or do u have talent with photo shop? what barrel? hows it performing?
Yes my special gift package from SPA contained parts to create the prototype quaterbore monster..
The barrel is a specially selected 16″ .25cal early BSA Lonestar hammer forged match grade barrel (removed from a new rifle years ago to fit a longer one)
These barrels are very well known for amazing accuracy and VERY sort after on the long range bench rest scene..
Full build documentation and performance figures to follow as soon as I get done.. :ugeekn: 
Tell us more…. was that a special gift from SPA? :whistle:
or do u have talent with photo shop? what barrel? hows it performing?
I got 2 coming.. at the WM spec! i was #2 for the first one so ill be getting that very soon :biggrinn: … then a about a week later i ordered another…
I made it in on the first group so I’m well on my way. If it’s the shooter I expect it may be one of several in our family.
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I see they also sent u a second valve assy…
was it different from the previous one? if so in what ways?