Project Hw85

[bigmac 97kt 13,812]

Cheers for the nice comments guys! I'll stick some pics of shot string and groups up when it's done. Got a wedding to go to this weekend so won't be done till weekend after but ill get there!

 

And yes mac bikes are fun! And my riding sounds simelar to yours lol.

Had some laughs and some tears lol

 

BOYS AND THERE TOYS

 

looking forward to seeing the rifle back together Tom

 

atvbjimmy :thumbs:

[tomburras 2,730]

Bit of an update......

 

Very strange but after a tester putting it together with the short stroke kit and a spring cut to a nice lentgh with some preload it was only making 6ft lbs!, I was only testing to see what sort of spring power/pressure is needed to get it up to power. So I fitted a full lentgh genuine hw spring and the extra tension needed to cock it caused the back of the piston to be pushed hard against the cyl on cocking causing it to gall and caused a mark on top of the compression tube on its first cock! I could feel it so stopped immediately to investigate.

 

It diddnt do that with a lighter spring but diddnt make the power so I popped off the short stroke extension and fitted the standard spring with minimal pre load and put it together. And the piston slid smooth as silk up the compression to be with zero spring noise and over the chrobo was 11.5 ftlbs and really nice smooth and quiet to shoot with very small amount of recoil.

 

So.... I think I will not fit the short stroke but instead fit a genuine hw spring with minimal preloaded instead, quite a suprising outcome! But that's the way it liked it.

 

The 85 has a slightly different piston to the 80/95 ect as the scope rail is bolted on top. This is because the compression tube is aluminium to save weight and would be damaged by a scope clamping on it and miss shaping it. Because of the scope rail bolted on top the piston has a cut out in the top so it clears the scope rail bolts. It is the cut out on top of the piston that galls as the extra spring pressure pushes the back of the piston upwards against the top of the tube.

 

This is good in a way as it makes the gun lighter and it also has a smaller swept volume than the but still keeps it's build quality but is in a smaller form.

 

So for now it's not short stroked but is fitted with a Vortek piston seal, tbt guides, genuine standard hw spring and updated cocking shoe allowing me to make a delrin piston sleve. And a dam good polishing (I'll polish the scratch out of the top of the tube whete the powerful spring caused the piston to gall.

 

Another strange thing I learned today was that the cocking shoe will also gall if the barrel pivot bolt is not tightened to the exact tension it likes - it's almost as if the bolt tension each side helps steer the cocking arm for the perect angle for the shoe to ride perfectly smooth up the cocking arm slot.

 

Apologies for the essay lol but thaught I'd share my strange findings. Its amazing how such a tiny thing makes such a big difference! And discovering/working together with all its little quirks will eventually end up with the gun exactly how I want it to be.

[charlie caller 3,654]

Good to hear its coming together mate, to be honest I am surprised you fitted the short stroke at all, I would not have thought an 85 would benefit from it, an yes, but its always good to experiment, thats how we learn mate, think you will have a nice smooth rifle there buddy.

[tomburras 2,730]

Cheers charlie caller iv had another test fit and it was the short stroke causing it to scrape! It must cause the piston to be at the wrong angle when cocking. This little 85 is like a mini hw80 so it's not a huge swept volume anyway but was worth a go experimenting.

[tomburras 2,730]

Here's a pic of the damage to the piston sleve caused by the rubbish designed old style cocking shoe....

 

 

It put pressure onto the sleve but the new style one runs on the cylinder with no pressure on the piston and sleve so I can now use a home made delrin piston sleve. With the old style shoe you could feel it riding over the spring coils!

 

So the work done on it is - full polishing to a mirror Finnish on piston, trigger and cocking slot and a hone out of the cylendar.

 

New vorteck piston seal sized perfectly to the cylendar for easy free sliding with perfect air seal.

 

Genuine hw spring cut to perfect lentgh so no powerwashers needed and then flattened ends and polished to a mirror.

 

Tbt guides and slip washer fitted with ends of them polished too.

 

A home made delrin piston liner with new stype cocking shoe. The cocking shoe was smoothed out and polished the running surfaces too.

 

Lube wise the spring and guides where coated lightly in spring grease and a small coating of bum slide round front and back of the piston seal. The trigger has a small amount of grease on the sears too.

[tomburras 2,730]

Here it is back together....

 

 

 

The nice shiny sticker....

 

 

The result - mega smooth! Nice and easy to cock and very quiet, zero twang and a very gentle nudge to the sholder when shot. Sounds like a completely different gun! It's shooting at 11.3 with AA fields. I'm over the moon!! I'll try put a shot string up later but was getting 6fps variation over 10 shots immediately after rebuilding.

[si brown 8,486]

excellent result tom

i bet your well chuffed!!

looking forward to your hunting posts

the 95 has re kindled my youth.. good times to come

atb si

[tomburras 2,730]

Same here with this 85! I'll get out with it soon and put a pic up. Will prob put a shot string up and a pic of a target after a bit of pellet testing.

[bigmac 97kt 13,812]

Now that's one sweet rifle Tom

 

now just get out and start to fill them bags with her

 

top class mate top class

 

atvbjimmy :thumbs:

[tomburras 2,730]

Cheers.... I'll get out with it soon and update!

[stealthy1 3,964]

I also fitted a Weihrauch spring in my 77 when I changed it last, good springs.

[tomburras 2,730]

I also fitted a Weihrauch spring in my 77 when I changed it last, good springs.

I previously messed about with a titan spring and had to cut a load off and had zero preload witch didn't seem right? The HW spring has a perfect light bit of preload that I imagine is how it should be - softer and a nice snug fit with no bounce.