Air Arms Air Arms S510XS low power issues

[terrykuz]

I have a Air Arms S510XS Ultimate Sporter that has poor velocity, and the power adjuster does not seem to help the issue.
High power only gets 526fps with 8.4 grain, and about 500fps with 10.3 grains on high setting. Velocity goes down ans the power is adjusted lower.
Any insight?

 

[DeanB]

Hammer spring backed all the way out

 

[cavedweller]

I have a Air Arms S510XS Ultimate Sporter that has poor velocity, and the power adjuster does not seem to help the issue.
High power only gets 526fps with 8.4 grain, and about 500fps with 10.3 grains on high setting. Velocity goes down ans the power is adjusted lower.
Any insight?

How old is the gun?
Due for a service?
what type of air source have you been using ? Dirty air is bad!
whats the condition of your orings?

 

[terrykuz]

The rifle has less than a tin of pellets and it is less than a year old. I have a Bauer Oceanus, so the air is good. I did not check the orings yet.
I appreciate the help and suggestions.