Theoben Rapid Forum

Looking at the thread of the reg or fastflow housing (3/8 BSP) into the action block a standard hydraulic extension coupling would fit. This would increase the regulated air volume behind the regulator and would be a cheaper and bigger than a custom pre-chamber or the in-line plenum of Raw (think they have the wrong thread).

While the looks would suck compared to the pre-chamber it would be the same for the Raw plenum extension (pretty sure it's the same thing)

Is there a flaw in my thinking??
Or am I missing something.

I have made an inline plenum 30cc for the Raw HM1000x and its seems to work very nicely.
It gave nice increase in performance in .22 .25 .30 and .35 still have to do some tuning but for now I am happy with the results

How did you seal the threads?

For the first testing I used bonded seals, for the final product I made room for a O-ring.
Its now tight and not loosing pressure for about a week so it seals nicely

My "Best fittings" QF came with brass extensions intended to avoid having to cut the stock, but they also act as inline plenums,
I found moving the bottle forward makes it very front heavy, although OK if you shoot off a bench.

I only shoot from the bench and I have an carbon bottle so its not that bad.
But if you have a heavy bottle and take it in the field it could be uncomfortable.