Rapid mk 2 .22

[Otto]

I have an fac as above with 16 inch barrel. Shoots well enough but wanted a longer barrel . Also I can't turn the power below 885fps to 980fps max is that normal

[Brooksy]

The power depends on the set up of the exhaust valve and the hammer spring, also, the regulator, if fitted. Your block and valves will be ported to allow high air flow, but there are limits, as you've found.
Why do you want a longer barrel? That would give a power increase, which in turn, would require further tuning to get it right.

[angrybear]

I have an fac as above with 16 inch barrel. Shoots well enough but wanted a longer barrel . Also I can't turn the power below 885fps to 980fps max is that normal

Don't quite understand this ??
Do you mean your current power is below 885fps and you want 980fps ?
Is it reg'd or fast flow, what size exhaust valve & barrel port etc it all makes a difference,
but can't be talked about on an open forum because some stupid xxxx will turn up their sub 12.

[Otto]

Thanks for the reply, I am new to Theobens and am not sure what internals there are. It is a mk2 rapid 12 with a regular I think and a 16 inch barrel. The power won't go below 885fps when turning the back Allen key and goes up to 985 fps max in .22 with 15.89g Hades pellets.
Just wondered if this is standard . I am also wanting a 19 inch barrel or longer if you know of any.

[Otto]

I wanted a longer barrel for better efficiency and make it quieter .

[Squinty]

Thanks for the reply, I am new to Theobens and am not sure what internals there are. It is a mk2 rapid 12 with a regular I think and a 16 inch barrel. The power won't go below 885fps when turning the back Allen key and goes up to 985 fps max in .22 with 15.89g Hades pellets.
Just wondered if this is standard . I am also wanting a 19 inch barrel or longer if you know of any.

yes, no and unlikely  that it is regulated if you can go from 27 to 34fpe on the hammer spring adjustment.

885-900fps/27-29fpe with a decent shot count is around the average for a 16" barrel .
Whereas 985fps/34.5 fpe is high..probably around 38-39fpe with a 21 grain pellet..

Barrel length- should give you 10-15fps per inch, should be able to get 930fps with 18s and a reasonable shot count.

[angrybear]

If it's reg'd there should be an atmospheric breather hole Fast Flows don't have, see pic.
I doubt you'll notice any difference in volume, but Yes, 19" could be more efficient.

[Otto]

Ok thanks I will check
If it's not how much to add one ?

[Squinty]

£130? for one of Kev's short-cores, don't buy one off Ebay, they are unsuitable for FAC pressures and in my experience need setting up from scratch (at best)  and at worst unless you have a lathe you'll be sending it off to Kev to get sorted.

[angrybear]

Ok thanks I will check
If it's not how much to add one ?

The issue is that it involves more than just sticking on a reg, the barrel port needs work & the hammer set up might need adjusting
With a FF the valve & barrel port are sized to slightly restrict flow with a full bottle then allow the best flow as the pressure drops,
this gives the best power curve & longest "sweet spot".
If you want it reg'd I'd get Kev to do the whole thing.

[Otto]

Yes thanks I would