Tyrolean HW80 – Part 3

This is a quick update on the Tyrolean, but also a warning about after market springs!
I’ve had a bit of a change of heart this week about the future of the Tyrolean HW80. I was planning on stripping and repairing the stock, then sorting out a tuning kit for it. However a new project has taken over almost all of my space in the workshop which will be taking up space for a while.

I’ve also been trying to practise my standing shots a bit more in the garden, but my TX200HC is fairly loud. So I looked in the gun cupboard to see what else I had. It needed to be a springer, accurate, and silenced. The 80 looked perfect. Except for one major problem, it had no spring…

A quick trip to a local gun shop and yes, they did have an HW80 spring in. They also had the Titan aftermarket option in for only £2 more. I asked two questions. 1. Would it be a good fit in the gun with standard parts? 2. Would it need to be cut down much?
‘Yes they are a good fit’. And, ‘it will be very close to the right power, you might need to just collapse a coil’. Great I thought, so I paid and left a happy man.

Happy man didn’t last too long though.

As soon as I started to take the gun apart I thought that this Titan #2 spring looked waaaaay too big. The picture below compares it to my TX200 spring which makes 10.5 ft-lb.
I carried on anyway and got the trigger block off. Then I got the standard spring guide out and reached my first disappointment. The internal diameter of the spring was far too big for the guide. It was a very sloppy fit and I just knew it would be very twangy.
Carrying on, I got the piston out to make sure there were no hidden pre-load washers stuck inside (there were 2). Then started to reassemble.  Time for disappointment number two. The trigger block wasn’t anywhere near the cylinder. In fact there was over 80mm of pre-load! It was so much that I couldn’t even get close to putting it back together.

At this point I decided to do a test. I found a spare spring, measured it, and built the gun up with that. Then did a power test to find a rough efficiency for the gun. I got about 25% but only at 4 ft-lb. I guessed this should rise to over 30% at 11 ft-lb.
Then I measured the Titan #2 spring. With 80mm of pre-load, and then 80mm cocking stroke. The numbers I got were a spring constant of 8.477N/m. Giving a potential energy of 86 ft-lb. Assuming 25% efficiency this results in a theoretical muzzle energy over 20 ft-lb! It doesn’t take a genius to work out that collapsing a single coil isn’t going to get me down to 11 ft-lb. 

Fortunately I have access to the tools required to cut this down. I use a dremel (or other rotary multi tool) with a metal cutting bit to chop the spring down. Then a butane blow-torch to heat the end coil up, and a pair of pliers to collapse it down. A bench grinder with regular stone disc grinds the collapsed coil flat (and takes off any sharp edges). A 240 grit flap wheel, then 320 grit, then a rough polishing mop with the black compound, gets the end of the spring all shiny again. I also had to make a sleeve for the guide to cure the twang.

At the end of this i now have a spring with 21.5 active coils, and 2x2mm washers giving 11.1 ft-lb with 15.9 gr Air Arms Diabolo pellets. This is up to 35% efficient which isn’t too bad for a big 30mm piston Weihrauch. Adding another 2mm washer takes the power up to 11.8 ft-lb so it looks like it is sensitive to pre-load. To be fair though, it does shoot ok, and seems to be very accurate so far.

The moral of this story then is two-fold. Firstly do your research, unlike me who just buys things on a whim. Secondly absolutely do not use after market springs unless you have a chronograph and the ability to cut them down (even if the shop does tell you it will be OK….).

As for the gun, It is all together now and has a little Hawke Sport scope (set to 6x zoom and parallaxed for roughly 15 yards). All ready for my evening practice, starting tomorrow!

 

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4 Comments on "Tyrolean HW80 – Part 3"

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Alan Fisher
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Sir, how did you make the ‘sleeve’ for the spring guide? Out of what? Thank you……..Alan

John
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Great read Dan. How long did the Titan No.2 end up being? I did realise it was a monster and got a No.4 instead but so far I have baulked at the Spring cutting etc and it remains unfitted…No.4 is 252mm as supplied. John