Springer losing power

[Gardenratter]

Would anyone happen to know if 9 and half fpe with AA 8.4’s is about the norm for a BSA supersport SE .177?

It doesn’t bother me as the gun shoots lovely, is accurate and still packs plenty of punch for paper and rats but I’m a bit confused.. after purchasing this gun and putting a tin of pellets through it the gun was averaging around 10.3 if I remember correctly, a couple of months later and it’s doing 9.2-9.7

Am I going to end up with pellets refusing to leave the barrel until they’ve had a coffee or what?

Any thoughts appreciated

[CapitalBee]

First thoughts:

You haven't got a gas ram fitted? - They lose power like no one's business and (apart from the original Theoben and HW90) being sealed, you can't increase them back up.

Check the breech seal - If everything else is okay (no graunching or difficulty cocking), sometimes a simple breech seal replacement is all that's needed.

I'm not too familiar with the SuperSport but - it might need a new seal on the piston (are these O rings?)

Have you changed pellets? - believe it or not the variations you mention can be down to a change in pellet type.

[Gardenratter]

I’ve just realised something that may be the answer..

10 shots after the gun was bedded in.. 747, 751, 751, 749, 741, 744, 745, 742, 738, 743

20 shots a few weeks after applying some moly grease to the spring (most likely too much) 706, 708, 704, 709, 705, 712, 705, 705, 702, 703, 704, 704, 709, 704, 705, 705, 704, 711, 700, 701

So I’ve knocked 40FPS off the gun by over greasing the thing I think. On the plus side.. it’s fairly consistent, pretty quiet and very pleasant to shoot XD

[Neil54]

If it shoots nice and ghe pellets go where you point it, leave it alone.

Don't chase power over accuracy.

[Shed tuner]

I’ve just realised something that may be the answer..

10 shots after the gun was bedded in.. 747, 751, 751, 749, 741, 744, 745, 742, 738, 743

20 shots a few weeks after applying some moly grease to the spring (most likely too much) 706, 708, 704, 709, 705, 712, 705, 705, 702, 703, 704, 704, 709, 704, 705, 705, 704, 711, 700, 701

So I’ve knocked 40FPS off the gun by over greasing the thing I think. On the plus side.. it’s fairly consistent, pretty quiet and very pleasant to shoot XD

yes, gobs of stick moly will slow it down.. esp if there's a lot on the piston skirt too.

Also, you would probably have had a little lube in the cylinder burning off to...

As you say, if it shoots nice, just leave it alone

[maximus]

Unfortunately, if you put that much into the gun it will probably end up in front of the piston and dieseling but guess you can shoot it till that happens

[Hsing-ee]

I’ve just realised something that may be the answer..

10 shots after the gun was bedded in.. 747, 751, 751, 749, 741, 744, 745, 742, 738, 743

20 shots a few weeks after applying some moly grease to the spring (most likely too much) 706, 708, 704, 709, 705, 712, 705, 705, 702, 703, 704, 704, 709, 704, 705, 705, 704, 711, 700, 701

So I’ve knocked 40FPS off the gun by over greasing the thing I think. On the plus side.. it’s fairly consistent, pretty quiet and very pleasant to shoot XD

Personally I could not bear to have a rifle that was stuffed with grease, it's like thick bronchitic phlegm in the lungs of a runner. This is the basis of those 'tune in a tube' gloops in the USA and some people pretending they have Venom tunes in their HWs. If you want 40 fps off then cut the spring or remove some preload. I'd strip it down and relubricate, go to the 'Junior Artists' section of your local Tescos and amongst the powder paint and felt tips you'll find some inexpensive art brushes. Chop the handles down so they fit in your toolbox then use one to delicately paint a thin layer of moly grease on the spring. It should be more than a smear but not worthy of the title of 'coat'. It's a Super Sport so it's supposed to be Super powerful for doing the King of Sports i.e. ratting.

[Gardenratter]

Unfortunately, if you put that much into the gun it will probably end up in front of the piston and dieseling but guess you can shoot it till that happens

Worse case scenario wouldn’t it just burn off? I didn’t cake it on but put more than what most would I think.

I was paranoid about the gun being too dry, probably should’ve just shot it and not worried about it

[Gardenratter]

yes, gobs of stick moly will slow it down.. esp if there's a lot on the piston skirt too.

Also, you would probably have had a little lube in the cylinder burning off to...

As you say, if it shoots nice, just leave it alone

I’ve done some more chrono testing and it’s still consistent and accurately hitting where I’m aiming. With any luck it’ll stay above 9FPE which is plenty for the odd rat and some paper targets.

[NewPaul]

If it shoots nice and the pellets go where you point it, leave it alone.

Don't chase power over accuracy.

This is how I would look at it.

[TonyL]

Yep, although the power is low for a Superport, as a few others have said, I'd probably just use it for now until attention is next required.

[look no hands]

If you're that worried about too much grease on the spring, but don't want to take the rifle apart again, then just take the action out of the stock and with some kitchen paper towel and cotton buds, just wipe off the grease off the spring through the cocking slot, the grease will get redistributed again once the guns been fired a few times.

[maximus]

Worse case scenario wouldn’t it just burn off? I didn’t cake it on but put more than what most would I think.

I was paranoid about the gun being too dry, probably should’ve just shot it and not worried about it

It would take a heck of a long time. Usually accuracy starts to suffer with excess dieseling but if yours is still accurate then maybe leave as is.