Yup, tis a cheap chinese version of a decent gun, but as my above post says, I got 11.5 from mine out of the box, didn't know that til I'd got the chrono though...
Save up 40 quid and get a combro before messing with it.
If you put an Ox in it you'll nacker its working parts.
If you put any spring in it either with or without checking it it's your fault when the Police check it.