S410 is down on power

[oneshot99]

I got a lovely s/h AA S410 in almost new condition, the owner only used a tin full of pellets through it and I was happy until I started play with a crono and found it was around 10lb. I dont want it at the legal limit but would have liked it at least 11lb, yes I know I should have been happy and left along but I like to know the in's & out's so done some research and took it apart.
Gave it a clean and reassembled to find it was down on power to around 7lb? took it apart again and fitted new seals after making sure it was absolutely spotless, backed off the restricting screw so the air had clear travel fitted a stronger hammer spring and got around 9lb from it which was consistent when firing two magazine fulls on a full reservoir or air. I adjusted the pot made no difference so put it back to where it was, I dont want an FAC just get it to what I would be happy with around 11lb.
I realise the importance of cleanliness when working and do it to a high standard so I am left scratching my head as to why or how the loss of power, could it be something I have over looked.
This is the best gun I have used and so accurate it's unbelievable to an ex springer fan, even when down a little on power.
Any help very welcome

[Blackbaronfish]

When you say you gave it a good clean what did you do. If you put your location in your profile someone near maybe able to have a look.

BBF

[Raj]

Some basic checks ...

1. Clipping sound moderator?
2. Bolt probe O-ring intact?
3. Measuring at the peak of the power curve ... or at either end?
4. Chronograph batteries? Light conditions?
5. Air gauges working well?
6. Barrel clean? No cruds?

[Roger5]

Some basic checks ...

1. Clipping sound moderator?
2. Bolt probe O-ring intact?
3. Measuring at the peak of the power curve ... or at either end?
4. Chronograph batteries? Light conditions?
5. Air gauges working well?
6. Barrel clean? No cruds?

Did you make sure the transfer port seal went back in ok, Rog

[Mark112]

Hi,

When you say you tested it with a full reservoir I take it you mean 190 Bar. Don't test it at that pressure but at 130 Bar instead. This is around the point at which most S4*0s are at their most powerful. Typically mine are around a full 1 ft.lb down at 190 Bar. For more reading on this 'power curve' phenomena read this fantastically written text:- viewtopic.php?f=15&t=2942 Also make sure you have the transfer port o-ring properly in place and it's the correct one.

Mark

[oneshot99]

Some basic checks ...

1. Clipping sound moderator?
2. Bolt probe O-ring intact?
3. Measuring at the peak of the power curve ... or at either end?
4. Chronograph batteries? Light conditions?
5. Air gauges working well?
6. Barrel clean? No cruds?

I would like to reply to all because every single one of your comments have been good & taken on board. Yes the trasnfer port seals are new and changed every time I have done anything to disturb them as with all seals. #6 Barrel is spotlessly clean I made sure. #5 yes all fine. #4 yes new batt and all working fine. #3 I have tried it at various stages from full (190) right down to very low just to see how it shot, I think if it were perfect and shooting very close to 12lb then maybe I would be looking into peak curve etc more but at this stage I just want to get it reasonable (at least 10.5lb sort of thing). #2 is the only O ring have have not changed and been thinking this from the start but as the pin slides in nicely and a good fit I have put off changing this. YES I KNOW, I will do that asap and let you know if it makes a difference. #1 I removed this and it shot the same, didnt use a crono for that but used my ears and the time it left the muzzle and hit target was the same with no noticeable drop of power here.
Mark I will look into what you say, interesting. Cleaned it with turps then cleaned that off and re-oiled,
Sorry I havent named you all but I have read all and much appreciated, that you all for your time