Originally Posted by
TonyL
I started a similar thread a few days ago.
My main question was would a cheaper, more flimsily built break barrel result in a shorter transfer port, inadvertently making it more efficient, whereas some of the more chunkily and solidly engineered rifles have a longer TP, owing to their robust build philosophy?
How short (in other words how thin could the cylinder end wall be) could we have the TP and still retain strength and reliability? Some of the answers that were coming back did indicate that quite a few break barrels do indeed have quite short TPs.
I suppose that, as long as the internals are properly set up and balanced and we're not getting piston slam, this shouldn't be an issue?
I am new to this "problem" so bear with me, I deal with fluid dynamics but not in guns!
The relationship between any hole and the passage of fluid through it is complicated and the length Vs diameter relationship is critical, the longer a hole is the more resistance there is due to frictional forces at the edges, in effect a hole with a very small length will give much less resistance to the flow through it than a hole which is of the same diameter but longer
Also the condition (turbulence) of the fluid at the inlet and outlet will be very different for different length holes
I know none of this helps answering what is the best port but helps to understand
As i think you intimated Tony what about a gun with no transfer port, i.e. the barrel face is pushed back into the cylinder (with an outer seal) with the pellet already in the barrel, to stop piston slam what about some smaller diameter "probe" on the piston end that enters the barrel as the piston nears the end of its travel thus blocking the barrel and creating a buffer of trapped air?
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