I called that spring weedy not just because the wire diameter is thin, but also because the coil geometry is not uniform.
It looks like a spring from a discarded mechanical toy which has been squeezed, stretched and bent.

I assume that aero engine valve springs are high precision items with near perfect geometries (Is that so?)

Completely dependent on intuition, my feeling is that geometric non-uniformity produces discontinuity in the force/strength values along the length of the wire.
These discontinuities produce weak points in the spring where perhaps fatigue resistance is greatly reduced.

Hence the pawl spring shown might have a much shorter useful life relative to your Merlin valve springs.

Of course, all this is a distraction from completing the planned work on the Browning and further delays the return to work on the Lancaster (which is where I want to be).
Mike

Yes, a swiss watch and cycling more than 19 times a second.

Here’s a description of the action of the Feed mechanism from AP1641C:

I’ve found two photos (from Walter’s collection) showing the underneath of the breech cover.
Here:

You can see the feed lever diagonally bottom left to top right.
The cam grooves are in the breech block itself (see below) into which the knob on the left end of the lever fits.

The feed slide moves within the housing to the right.
The right hand end of the lever goes through a slot in the housing, connects with the feed slide and waggles it up and down (as oriented to the photos)
In both cases the slide is shown at the top of its travel.
This corresponds to a new round having been pushed onto the gun centre line against the two stops which I have already drawn and shown in earlier posts.
To pick up a new round the slides would drop down pushed by the end of the feed lever as it rotates to the bottom right position.

The good news from these photos is that the feed pawl has no teeth.

The crucial bit: changing feed direction from left to right of the gun

The pawl slide is ok. Its leg or hook is bolted on and can be on the other side with the slide itself rotated 180 degrees.
But what about the feed lever and cam grooves in the top of the breech block!

Let’s look at the breech block cam grooves and the action on the feed lever with these drawings which come from AP1224 sheets 1 & 2.
In the drawings the breech block is bright silver and the feed lever in green.

For the breech cover photos above we were looking up.
For these two Ap1224 drawings we are looking down.

So the top AP1224 drawing is the one that corresponds to the breech cover photos with the breech fully forward and a round on the centre line of the gun. The feed is from the left of the gun.

With the bottom AP1224, the breech block has gone to the back of the gun.
The knob on the feed lever has followed the groove through the turntable and has pushed the feed slide to its topmost position ready to pick the round waiting and held by the retaining pawl (see earlier posts)
There are two grooves with a steam engine turntable in the middle. One of the grooves is for a feed from the left & one from the right.

If the feed lever pivot was on the centre line and without the kinks shown on the right hand arm, just changing the turntable and using the second groove could not do the job of changing to a feed from the right. A new feed lever would necessary.

I think that’s avoided cleverly by offsetting the lever pivot and kinking the arm of the lever. But I need to prove that.

Oh wow! my head is spinning. At least there are no teeth to draw.
Mike

Help, please

In my work on the trunnion and ammunition feed area I have ommited the 3/32″ skin plate which fills the gap between the trunnion and the side bars. But I can’t for the life of me see how the side bars were fixed to either the trunnion itself or to the missing skin plate.

Can anyone help on this question? All these images come from Walter’s collection.

Here someone has stripped off both the side bar itself and the skin plate. The plate would lie between the two vertical lines. There are only two rivet holes which could possibly relate to the side bars. These are shown with arrows.

Unfortunately, the following image of the side bar shows that while there is clearance for those two rivets, shown by arrows, there is no internal flange which could join the side bar to either the skin plate or the trunnion. These two images are sections from the same photo.

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Now looking at the top of the trunnion and side bar, the joints between the trunnion, skin plate & side bar are fine, almost as though they were welded and ground flat. The red lines are witnesses to the joints. The inner line is the joint between the trunnion & the skin plate; the outer between the side bar & the skin plate.

Here is the same image without the witness lines.

A further thought, if the two rivets indicated in the first image did join the side bar to the skin plate & trunnion, would such a fine joint bwteen them be possible. My argument being that the two rivets lie at the bottom of the side bar and as a result the free join at the top of the side bar could not be as fine as shown in the photo.

Comments are very welcome. This has peeved me for some time.
Mike