Tuning Is 10 bar a huge difference in tuning

As I get into this more and being completely new to PCP guns I may have stumbled onto a tuning advantage.

My Brocock Sniper XR Magnum came with the secondary reg set at just below 160 bar. I'm shooting H&N Hunter extreme's and at 30 yards my 10 shot groups are all touching if not overlapping. I'm shooting off a tripod with only me being the rear support. I figured the group size was me getting up to speed in accuracy. I've never let my bottle pressure get lower than the 160 so all my shots over these first few weeks have been at the same pressure. 

This morning I was shooting and the pressure made it down to 150 bar. I figured I'd put ten more pellets through it and call it a day. Well that group was just maybe a 1/4 inch lower but all ten shots were basically one hole.
Freak increase in accuracy or did I find the sweet spot for that gun?
 
the way i see it everything affects things .. not only the pressure itself but how the vibrations sync up between valve and hammer etc . it all affects what the gun is doing as the pellet heads out the barrel .. when you find something that works take notes lol ..

Right on.

A tune is a personal thing but exactly why I run tethered at lowest pressures I can. I'm more interested in testing my ability and the projectile over the guns efficiency. Any reg,valve, hammer, spring, flow/porting can be done. 
I'm interested in the barrels that can come close to ST pellet performance & my own abilities since I can't really get out & compete.

A 40fps spread equates to a 1/4" drop at 50 yards with a JSB 18.13 at 880fps down to 840fps. So we definitely know that slight variances in absolutely anything, make a measurable difference on paper. 

If I want to shoot & walk about I use a springer or any 1/2 way decent PCP. A reg is not needed for this and equates to one more place to leak. 
In my opinion a best all around airgun is a RWS or HW, AA springer, if newbies are wondering.

Good question & just my honest thoughts from where I sit. If I wonder if I offered anyone I tend to chose not to answer or post, lol.