Air Arms Owners Club

Hi All
I'm sure someone can help me out with this so here goes.
After reluctantly parting with my 8 month old Daystate Huntsman Regal having made my mind up to get either a HW100 or US I plumped for the US to accompany my excellent TX200 Mk3.
Every time I get a gun I run a few mags through my Combro Mk 4 just to benchmark how the gun develops as it breaks in so I duly did this with the US.
However, after 4 mags it vented air at around 130 bar. (Difficult to be more precise because of the new type gauge. Not one of my favourite things on the gun I must admit!)
Using AA Diabolo Fields at 16grn from a full 190 bar fill I averaged 11.90 ft/lbs which left me very impressed. The down side was the venting issue so after only having the gun for 2 days it was returned to Air Arms.
I got the gun back yesterday and after a couple of mags, chrono'd it again but this time using JSB Exacts at 15.9grn from a full fill. This time it averaged 10.89 ft/lbs which is in my opinion quite a considerable variation from the original power.
The venting problem appears to have been resolved as I got 90 shots from a fill before losing accuracy without venting but why have I lost 1 ft/lb of power?
I'm guessing that I was using more air originally because of the higher output and to resolve it Air Arms have toned it down a bit?
Any Ultimate Sporter owners out there that can advise?
Thanks in advance.
Andy

Hi,

11.9ft.lbs with AADFs would probably mean that a heavyweight pellet like Bisley Magnums would have been over the limit. They are about half a ft.lb higher in my S410 in .22. I believe that your US set to about the right figure now. It should improve slightly with time/shots and you will also find that it will be more powerful at a lower fill pressure. Mine is best between 160 and 100 bar peaking to its maximum at about 130 bar. Shooting and recording the values of a full shotstring will reveal the best fill and refill values for your specific rifle.

Mark

Cheers Mark
I'll try that.
Andy

11.9ft lbs?
Are you sure you had the correct settings in the chrono?

Too close for comfort.......