Tuesday, November 17, 2009

Some Notes on Reassembly of the Haenel 310

Reassembly of the Haenel 310 was pretty straightforward.

I gave the leather seal a trim as the leather had mushed a bit. Later I also scraped the sides with a razor blade to remove some of the thick dirty grease....

It's important to line up the screw hole with the piston. See how grey the piston seal is? I scraped that off...

When the piston is slipped in I had to stick a thin screwdriver between the piston and the bushing so I could then lever the bushing into place.

Then as I showed I used a rod (in this pic the handle of a pin punch) to put the bushing in position.

And captured it with a pin punch.

The end cap mates with the tangs on the trigger block.

The end of the safety mates and locks over that bent tab inside the trigger group. So the safety is rotated 90 degrees and pushed over and then rotated back...

The shot I have varies in size...

That's the same piece of shot as above, out of round by .11mm (.004")
I need some truly round shot.

In any case after the first reassembly velocity had crept up to 280 fps from 250. Not great. So I tore it down again and as I said above, shaved the sides of the piston seal, nothing extreme but I wanted to get down to clean leather from the grey mess of the piston. I had a feeling that the greasy dirt was robbing velocity. For once I was right. It is now doing between 300 and 320 fps. I have the feeling, as Tom Gaylord said, that oiling the seal often helps a lot. I'll keep an eye on the velocity over time.

I also think that the out of round shot robs some velocity due to pressure loss around the edge of the shot. I pushed one through the barrel and there were only two spots where the rifling engaged the shot. Anyone have some German Punktkugeln in 4.4mm they want to send me?

Now I need to make a new sight elevator...

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