Ultimate Sporter

[Firecone]

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

[Mark112]

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

[Firecone]

Cheers Mark
I'll try that.
Andy

[Mcdemon]

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

Too close for comfort.......