Tuning Bsa r10 se tuning

Hi I'm new to the forum, im from the uk and trying to find anything out over here about rifles youd have more joy finding rocking horse 💩 I'm looking for some advice on tuning my bsa r10 se I've fitted huma regulator set at 135bar upped the transfer port to 5mm ported the barrel and polished. Ive polished just about everything I can in the rifle, ive upped the hammer spring ive managed to get the power I'm looking for but seem to have gained power at the cost of accuracy been looking at trying to get a upgraded valve spring bit the ones I've seen are the same in the 12fpe version as the export version 
 
Thanks for the replies.The barrel is fantastic it was unbelievably accurate and think I'm getting it back i dialed the reg down again today and started from scratch a gradually brought the reg pressure back up and at each pressure setting gradually built up the hammer spring its took alot of air and pellets but accuracy is back! It was not pellet fussy at all before I was using jsb hades, predator polymags, rws superdomes, bisley magnums . Bisley pest control and you would get a group out of all of them. So today I went back to the drawing board and started fettling it again and at my zero at 35 yards im getting ½ inch groups again relief I haven't knackered my barrel 😁 tomorrow im going to push it out further and put it on the chrono and see what sort of shot string I get all I know is that as it looks ive managed to keep the power up on a lower reg presure get the accuracy back and get a Higher shot count per fill than I was yesterday, so hopfully heading in the right direction. I was worried about where I had ported the barrel and polished it but I had it all apart today to check there was no burrs or anything and it was all good. I'm at 140 bar at the minute but hoping I can push that to 150 im aiming for 900 -950fps if possible with such a short barrel. I'll post my results as soon as I get chance 
 
You may not get better accuracy pushing it past 900fps unless you are shooting 22 caliber 21gr Baracudas (the pointy ones) which fly great up to 1055fps or 25gr JSB monster or redesigned up to 950fps or the Eun Jin Seneca 28gr domes good till 1055fps too or FX Hybrids up to 950fps out of the BSA barrels.

If it's a 177 then only the 7.9gr and 10.5gr brown boxed Crosman Premiers and 13.4gr JSB Monsters and heavier shoot well past 900fps till about 950fps. 

If you are using pellets other than what was mentioned then between 850-880fps are the sweet spot for both calibers.
 
Its a .22 ive been hoping to have a play with some slugs and was trying to get more pellet speed to use something like the jsb knockouts 25.39g or the fx hybrids slightly lighter 21g if the rifle will fire them. the whole slug thing has been intriguing me for a while and looking at the balistic coefficientsy of them think its opening up a whole new level of airgun shooting! Was even thinking of fitting a longer bsa barrel to get more velocity but it's a way I can justify getting another rifle 😉👍😂