expert advise needed for bsa r-10

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H

Hubertus

Member
Nov 30, 2017
335
13
Vienna, Austria
Hello,

its about a BSA R-10 SE in .177
5,5 fp because its used as target rifle for 10m (i know there are better ones but i cant change that)
extreme low fps spread - stock regulator working good.

issues:

very loud muzzle blast. you need air protection without ldc
shot count only around 150
1,2mm tranfer port
stock bsa spring preload adjuster maxed out 
regulator set point around 80 bar (tells me chronograph)
no spring guide

what i tried:

preload adjuster turned backwards so no preload when uncooked = energy level decreasing 
softer spring = energy level decreasing

my thoughts and i dont know if they are correct:

poor down tuning with a very small transfer port (air-jam)
i think the airflow is extreme restricted and it takes the air a long time to get through (loud muzzle blast?)
or and additional hammer bounce (because of the small transferport?) or just the stock spring with preload (even when uncooked)

my thoughts of a good down tuning:

bigger transfer port for and faster air flow
softer spring because with the stock spring would it be much too high
eliminated hammer bounce (i think there is) because of the softer spring with no preload uncooked ?

what you guys think ?





 
Hi,
yes, problem was the small transfer port
drilled to 2mm and i had to turn the preload adjuster completly back and still needed a softer spring with no preload.
shot count went extremly up and much less muzzle noise.

i cant believe that, whoever did this, still used the stock spring with max. preload for a 5,5fp!!
stupid and no knowledgte of pcp's!!

now im thinking if the efficiency could be more increased by using a 2,5 or 3mm transfer port with a lower spring ?
the bsa hammer seems to be very light. this could be good for using a lighter spring ? i could imagine that the force from a lighter spring couldnt be enough for a heavier hammer..

 
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"Hubertus"Hi,
yes, problem was the small transfer port
drilled to 2mm and i had to turn the preload adjuster completly back and still needed a softer spring with no preload.
shot count went extremly up and much less muzzle noise.
i cant believe that, whoever did this, still used the stock spring with max. preload for a 5,5fp!!
stupid and no knowledgte of pcp's!!
now im thinking if the efficiency could be more increased by using a 2,5 or 3mm transfer port with a lower spring ?
the bsa hammer seems to be very light. this could be good for using a lighter spring ? i could imagine that the force from a lighter spring couldnt be enough for a heavier hammer..

Click to expand...
Seems like it was someone who is used to tuning unregulated. With an unregulated gun you need to restrict the air flow (via small TP) to flatten the string. I've found it best with the regulated tune to open it up. Use the air pressure and hammer strike to control the energy level.
I have not done much low power tuning (under 12fpe) but I would think that opening the TP and then restricting the valve volume would be even more efficient.
Not sure about the valve in the R10 but both of Techstar and Ultra had brass spacers in the valve to lower the output. I removed the spacer from my 10fpe Ultra (.25) and opened up the TP and it's shooting 27fpe on the regulator.
If yours doesn't have the spacer, and it will fit you are more then welcome to one of them. (I saved them both)
 
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