Lacking a chrono, I find that old Eley Wasps fired against a flat pellet-catcher (inserted paper prevents rebounds) provide a guide as to the power of a rifle, determined by the flatness of the pellet.

Louis Van Hovell, from this site, very kindly sent me three steel washers/spacers of approx. 1mm each. This is because one of my two Mk3s displayed power that appeared sub-optimal, evidenced by pellets where their centres were well raised above their surrounds, after firing into the pellet-catcher.

After placing merely one greased washer inside the piston, the situation changed. This time, the pellets were flattened throughout - including the centre.

In a another development, some months ago I bought an old unused Mk3 spring from a BBS member. I noticed this was between 1 - 1.5cms longer than my existing Mk3 spring (I should have measured both but overlooked this before re-assembling the rifle). Given it was something of a task to screw the trigger unit back into the cylinder, because of pre-load of the unused spring, I experimented instead with a single washer - which appeared to have the desired effect.

Questions:

1 I did not expect a single washer, about 1mm wide, to have such an effect. How can this be? What are the mechanics at work here?

2 Would additional washers, either in the piston or at the trigger end, have an equal added impact? It seems I have already achieved my objective with merely one washer but I presume additional washers would produce a further boost or would there be a diminishing return?

3 Would the longer spring have had a similar outcome? Does a longer spring (assuming the power of the spring is similar on a per cm basis) raise the power of a rifle? This sounds obvious but I recall reading on this site that a longer spring does not necessarily raise the power and can diminish it.

4 Finally, given the existing spring within the rifle is some 1 - 1.5cms shorter than the unused spring, I am presuming that this has occurred over a period of some 46 years, due both to the use of the rifle over this time frame and the pre-load within the rifle. Would this be a reasonable assessment?

Whilst the above refers to a Mk3, the questions would appear relevant to other rifles.

Rgds to all
A