HW50 - velocity expectations

[evert]

New Chrono battery, and took the spring and guides out of the old leather sealed gun that was doing 730fps, and put it in the "new" synthetic sealed Hw50.
This spring is a bit shorter, but has thicker wire (3,1mm) and smaller ID at about 13,5mm.
Th gun is still sealed with JM/ARHs 25mm HW seal, that I have sized a bit.
Recoil is very soft, and there is no vibration. Seems like the shorter stiffer spring gave a bit softer recoil.
I might get a few more fps by changing the seal or sizing it a tad more, but I'm afraid this might make the gun less pleasant to fire.
10 shots over the chrono gave an average of 680fps with 7,9 JSB, and a maximum spread of 8fps.

I'm happy for now, but would like a bit more velocity... Its time to shoot some targets and see how the gun runs in before any more changes are made.

[TonyL]

At just over 8ft.lbs, excellent consistency and very much sounding like you're liking the firing cycle, I think I'd be patting myself on the back, enjoying the lovely little lightweight for what it is and leaving those higher velocities for the "big boys".

[evert]

The recoil is very soft, but I think it could be a tiny bit bit faster without hurting anything, it still feels somewhat restricted. It is good, but it might be possible to get it even better

[TonyL]

Understood, sir.

[evert]

Did some work on the old Leather sealed HW50s, which turns out to not be leather sealed
I totally forgot that I had converted the piston to take a 25mm diana seal
This increases stroke some mm's, and is probably the reason why this gun now does over 9fpe with the ARH/JM E3200 spring.

[TopDog]

Did some work on the old Leather sealed HW50s, which turns out to not be leather sealed
I totally forgot that I had converted the piston to take a 25mm diana seal
This increases stroke some mm's, and is probably the reason why this gun now does over 9fpe with the ARH/JM E3200 spring.

That's why it's important to have all the internal dimensions known! That way (and I am a believer in matching theory to practice!) one can navigate oneself to the required configuration!

It is relatively easy to compute what the outcome should be for a particular action when one has a starting figure for MV/(ME) and the details for the dynamic part of the action!

It's all good fun though isn't it!

atvb
David

[evert]

At just over 8ft.lbs, excellent consistency and very much sounding like you're liking the firing cycle, I think I'd be patting myself on the back, enjoying the lovely little lightweight for what it is and leaving those higher velocities for the "big boys".

After some shooting, I am thinking about taking your advice and leaving it alone for now.
The shotcycle with several pellets is really nice, and accuracy is as good as any other really good lightweight springer I have shot.
The only guns that better it are my mid-stroke Tx200 and perhaps the missus HW97k.
I like the gun better than any HW30, because the longer stroke gives a softness that the HW30 is missing (in my personal opinion), and the gun is a tad bigger so it suits a grownup better.

[TonyL]

Sounds lovely, evert.

I must get around to having a little tinker with mine at some point. I only have the one. Just a de-twang / check / de-burr / lube will do me once I get my pass stamped.

[evert]

It's all good fun though isn't it!

Yes, but I get lost in the moment and forget to take measurements of the action.. Yesterday, when working on spring guide fit I forgot to take measurements of other things.

[evert]

While you have yours apart, please can you check whether the transfer port is straight or angled on your 50.

I have a 50 project going at the moment and it took me by surprise to find the transfer port is angled.

Have had three of the four HW50's apart now, and my leather sealed rifle and dads synthetic sealed rifle both had slightly angeled transfer ports.
I might need to check my synthetic sealed gun again, as the ports are less angeled than I expected.
When you stated the were angeled I was expecting the ports to start out in the center of the cylinder, like other angeled ports, but these are less engeled than I was looking for when I opened the first gun.

[evert]

Did some more work today:
Removed the brass tophat, and made a delrin one that spaces the spring to the absolute max (had to remove a 0.5mm steel washer to get it to cock)
The rifle now does 705-715 with 7.4grs Umarex Mosquitos, which is around 8.3fpe.
Shotcycle is fast but soft, and recoil is lower than with the brass tophat.
I'm happy with this, and probably ready to shoot the gun for a while

[TopDog]

Well done and you are making a good choice. Enjoy the rifle for what it is; that's really what it's all about!

Stay safe and well!

atvb
David

[TonyL]

Lovely; well done evert.

[Hsing-ee]

OK I have a couple of these, one in each calibre.

I want the .177 to do 10.5 fpe. What do I need to do? I have both the leather and a spare synthetic seal piston.

I was thinking to get a Vortek spring and fit an Original Diana adaptor and synthetic seal.

Can't see the point in this at 8 fpe, my 30S can nearly do that.

[evert]

I think it all depends on what kind of firing cycle you want to end up with Evert.
Between 9.5-10.5 ft lbs can be obtained in .177 with a standard piston and synthetic seal but you do need a stiff spring.

I want the .177 to do 10.5 fpe. What do I need to do?.

The seal that has given me the highest velocities in 25mm HWs has been the Vortek seal.
Combined with a stiff spring and perhaps some extra piston weight, you probably get the highest velocities.
But its probably not going to be pleasant to shoot.

It looks to me like theres room for some extra mm's of stroke with a custom piston in the old HW50 and 55.