s200 mk3 help

[render87]

ok so ive got a s200 mk3 in 177 and the difference between bisley magnums running at now 11.7 and jsb at 7.8 is massive. if/how do i reduce the differnce between the two as the rifle prefers (most accurate) the jsb but as its for hunting i would like the jsb to be at around the 11 mark any help would be great cheers

[Mason]

Are you using the correct pellet weights in your calculations?
What speed are they doing?

[eddie666]

the jsb must be very heavy , find some pellets that weigh less , till you get what you want,

[render87]

the biz mags are 11.7 now (was abit hot) and the jsb about 8ftlbls and yeah all weights have been checked

[Timmytree]

the jsb must be very heavy , find some pellets that weigh less , till you get what you want,

In this case it's JSB Exacts Eddie, only 8.4 grains.

[eddie666]

the jsb must be very heavy , find some pellets that weigh less , till you get what you want,

In this case it's JSB Exacts Eddie, only 8.4 grains.

they must be tight fit to only get 7.8 fpe

[render87]

just a quick update as i was running some other pellets (all at 160bar) i noticed the power drops after the first jsb first i used cheap vmx pellets 8.2 and got

1.11.30/788
2.11.28/787
3.11.24/785

next were crossman premier heavy 10.6

1.10.79/680
2.10.70/677
3.10.58/673

then the jsb 8.4
1.10.94/766 (i thought yes that will do)
2.8.69/683
3.8.62/679

got to be seal thing surely as it does this every time i switch from another pellet to the jsb first shot fine and then lose 2odd ftlbs

[Timmytree]

Clutching at straws now, barrel clean and new breech seal, get your hands on a tin of AA Fields and try them.

[render87]

seals in the post should get them tomorrow hopefully but i only just replaced it so i dont know also just put some accupels through and getting 10.6 so if they group fine ill just stick with them i think should be plenty for hunting

[eddie666]

do not trust the gauge on the rifle they can say all sorts ,

fill to 190 and shoot with one type of pellet,
shoot strips of 10 shots on 15 seconds for each from the time you cock the rifle, then 2-3 minuets rest before the next strip of shots to let the barrel cool ,
this will give you a consistent time of pressure in the chamber ( if there is a seal leak ) all shots will be about the same consistence, on the chrono readings, write down what your rifle gauge is reading after every 10 shots ,
if you do this for 4 x 10 strips of shots or when ever your gauge says 100 , you will get a good idea were the sweet spot of consistent shots start and finish also what your rifle gauge is telling you.
even if you have a leak the shots will still show you whats going on.

make sure your chrono is working right and has a consistent distance and light and same timing with every shot , if you weight the pellets thats better but is not crucial ,
constancy / timing / cooling / distance and what your gauge is saying , sort out a timing system thats easy for you and the chrono to achieve, then if some thing shows up wrong it should be a constant wrong ,