AT 44 Tuning
Return to Hatsan AT44
before modifications - from the factory
the gun was unboxed a few mags fired through and then on the crono with some 7.9 grain pellets  :-
All guns tested using the Blue Shot Android application - connected to the Combro Crono

Really not bad but as most new UK guns low on power  9 - 10.2 feet lbs mmm - my target was over 11 Ft Lbs and way flatter shot string - 700 - 750 fps is not great

First job was to fit a reglator, set to 95 bar  - Info here
Open up the transfer port to 3 mm and fit a custom spring and adjust

After regulator fitted  :-

Nice - much flatter curve but falling so better, and power up to closer to the limit - but much lower shot count ! way too low something needs adjusting !

My first thought was that the valve in the gun was staying open for longer than required so the pellet is well on the way to the target before the valve is closing -
I needed to prove this before messing around  - as my brother tells me "lets not make the problem worse by guessing " so

It occurred to me it would be good to see what an efficient gun uses air wise to prduce a full power shot ......
A  childs balloon was sourced and put on the end of the barrel of the C-State gun and the trigger pulled, the neck of the balloon quickly closed to capture the pulse of air
this was then  bubbled into a graduated container and measured  150 ml of air per shot - a good starting point ! I now have an idea of what to aim at, - a full power shot is possible from a simular gun with 150 ml of air

Next job repeat the balloon test on the Hatsan - result 300 ml of air - double per shot - something needs adjusting here ! the gun is not working efficiently
I decided to strip the gun and reduce the pre load on the hammer spring - one turn cut off , reassembled and tested - great we are down to 200 ml of air per shot better but not great - we still have 11.6 ft lbs so no loss of power just not wasting so much air the valve must still be open when the pellet has left the barrel.
another strip down
half a turn from the hammer spring - rebuild, now 160 ml of air, this is the current state of play as i have some more mods in mind and will revisit the spring when i have completed these

I think a total result - the gun is now using almost half the air it was / shot  and still giving full power

shot string after tuning

Baloon test update 15/02/13

Update 12/01/13
took the gun to the club today - filled to 200 bar
took a crono reading - 11.6 ft lbs
took 90 shots checking the output every tenth shot (to cold to take every shot and the logging not yet sorted)
shot 100 the power had dopped off to 11.2 Ft Lbs
total result 100 shot at very good power

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