Really didn’t know where to post this but I’ve got a HW97 springer that I believe the spring has broke on it and trying to find some that does work on springers.
Gunsmithing HW97
- Thread starter drglock
- Start date
I can do it.... There are also lots of kits out there that have shorter springs that require less preload. If you went that route, you could likely do it yourself. If you keep the factory spring , you will likely get hurt !! The HW is an incredible platform to start from. [email protected]
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I’ve got a Maccari kit for it. New HW95-77-97 GSX OS UK Kit -Adjustable Power and figured to detune it to 12fps while at it. I’ll shoot you a pm in the morning.
If you start at the muzzle end, you can make it's cocking lever and detent button much nicer. You can change the shape of the piston with some wet / dry. You can make it's center smaller than it's ends. You can shorten the piston by about .12 and add some needle bearings to reduce the torque produced by the spring while it's going through it's compression / extension cycle. you should add a grease baffle to keep the grease in the piston and out of the compression tube. You can pull the front seal off and round over the sharp edges to allow for free rotation. The trigger sear can be lapped off and the trigger spring replaced. All of that can be done for less than $12.00 So much cool stuff you can do to a HW-77 / 97
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Thank you Dr. I like the gloss looking stock as well.
As well as refining the internals around the piston and compression chamber, I thought I wanted to make cocking the gun more pleasant as well. The first photo simply shows the cocking lever in an un-latched position. The second photo is of the button that your finger has to depress to push the cocking lever detent aft and out of it's receiver hole. It has a spring behind it so I changed that for a lighter one. The third photo is of the cocking lever detent. It's spring was fairly heavy and it was staked at the factory and meant to be permanent. I replace it as well. By replacing the two springs, my finger had to do less work. I have heard people say move the entire assembly forward.... and by lightening the spring pressure on the detent, they minimize any upward barrel deflection...... and even replace the spring with foam or some other non metallic noise abating material. I could claim all manner of craziness but I did it purely for operator comfort. Yes... I used to shoot that much between matches.
I should ad that the cocking arm detent button has a very slight taper to it's nose. That's why it doesn't rattle
or have to be in a precision bore.
I highly recommend that you never let go of the cocking arm while you fingers are in the pellet loading area and that you never defeat the
anti-bear trap safety. In Michigan, at a local match, I saw what happens to a thumb that got in the way of a slamming mechanism. ( Think Guillotine ) If you allow it to happen, your really in the way of the moving compression chamber, piston, spring and the entire cocking lever assembly and all closing at high speed. Worse still.... all of that mass wants to continue to move because of the spring and the moving lever.
Enjoy and live life to it's fullest but don't become careless. My activities are not particularly forgiving If I get in over my head.
I wish I could convince you that you can / could do everything that I have ever done.....
Shawn
As well as refining the internals around the piston and compression chamber, I thought I wanted to make cocking the gun more pleasant as well. The first photo simply shows the cocking lever in an un-latched position. The second photo is of the button that your finger has to depress to push the cocking lever detent aft and out of it's receiver hole. It has a spring behind it so I changed that for a lighter one. The third photo is of the cocking lever detent. It's spring was fairly heavy and it was staked at the factory and meant to be permanent. I replace it as well. By replacing the two springs, my finger had to do less work. I have heard people say move the entire assembly forward.... and by lightening the spring pressure on the detent, they minimize any upward barrel deflection...... and even replace the spring with foam or some other non metallic noise abating material. I could claim all manner of craziness but I did it purely for operator comfort. Yes... I used to shoot that much between matches.
I should ad that the cocking arm detent button has a very slight taper to it's nose. That's why it doesn't rattle
or have to be in a precision bore.
I highly recommend that you never let go of the cocking arm while you fingers are in the pellet loading area and that you never defeat the
anti-bear trap safety. In Michigan, at a local match, I saw what happens to a thumb that got in the way of a slamming mechanism. ( Think Guillotine ) If you allow it to happen, your really in the way of the moving compression chamber, piston, spring and the entire cocking lever assembly and all closing at high speed. Worse still.... all of that mass wants to continue to move because of the spring and the moving lever.
Enjoy and live life to it's fullest but don't become careless. My activities are not particularly forgiving If I get in over my head.
I wish I could convince you that you can / could do everything that I have ever done.....
Shawn
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Hi Shawn,
When you say shorten the piston do you mean increasing the stroke, I've read about this but haven't seen how it's achieved I'd be keen to see how you did yours if you want to share.
Mike
Hi Mike,
I shorten the piston just enough to put these needle bearings behind the spring, about 1/8"
To increase the stroke on a HW you would have to cut the back of the piston for clearance but also shorten the
piston rod. If you do that, you will also have to watch the spring because at some point they compress to solid.
Truly you want the skirt of the piston to bottom out on the rear block and not have the cocking action stopped by the piston
rod banging into the light blue trigger hook.
If you did a quick search on say die springs and life cycle, You will find that springs compressed to 25% have an infinite life, 35%
maybe a million cycles, 50% 100,00 cycles etc. They don't like being over compressed. ALSO, any extra energy that you put into the
system goes straight to the trigger. IE: The Rekord trigger is also used in the R7 and you can get it to break at a lighter weight than the 97
simply because of the spring power. Most of what I have seen is SHORT stroking a spring gun. Meaning they simply make a thick front
seal to reduce the useable volume. Ebay has one now from Custom Seals. Paul Short does all kinds of things with spring guns. He has the blue piston below that is all polymer except for the rod and the front end, The one above looks to be from a AA TX.
You need to ask yourself a couple questions.... At what point is the air flow restricted by the orifice size? ( In simple terms, that is how they limit a PCP ) AND...
After my gun is buttoned or poly pistoned or titanium pistoned etc. HOW do you know ( quantify ) that you have improved anything as opposed to just changed things?
What is it that your looking to accomplish??
Shawn Carroll
[email protected]
I shorten the piston just enough to put these needle bearings behind the spring, about 1/8"
To increase the stroke on a HW you would have to cut the back of the piston for clearance but also shorten the
piston rod. If you do that, you will also have to watch the spring because at some point they compress to solid.
Truly you want the skirt of the piston to bottom out on the rear block and not have the cocking action stopped by the piston
rod banging into the light blue trigger hook.
If you did a quick search on say die springs and life cycle, You will find that springs compressed to 25% have an infinite life, 35%
maybe a million cycles, 50% 100,00 cycles etc. They don't like being over compressed. ALSO, any extra energy that you put into the
system goes straight to the trigger. IE: The Rekord trigger is also used in the R7 and you can get it to break at a lighter weight than the 97
simply because of the spring power. Most of what I have seen is SHORT stroking a spring gun. Meaning they simply make a thick front
seal to reduce the useable volume. Ebay has one now from Custom Seals. Paul Short does all kinds of things with spring guns. He has the blue piston below that is all polymer except for the rod and the front end, The one above looks to be from a AA TX.
You need to ask yourself a couple questions.... At what point is the air flow restricted by the orifice size? ( In simple terms, that is how they limit a PCP ) AND...
After my gun is buttoned or poly pistoned or titanium pistoned etc. HOW do you know ( quantify ) that you have improved anything as opposed to just changed things?
What is it that your looking to accomplish??
Shawn Carroll
[email protected]
Attachments
Hi Shawn
Thanks for the reply, increasing the stroke and the swept volume are what I'm looking to achieve so more power and still be decent to shoot. I know venom used to do a longer stroke high power kit but trying to find information on how to recreate one is hard now they are no longer available, for some reason there seems to be an information blackout on tuning air rifles for power. I know it's a balancing act and just chucking in a huge spring isn't the answer, I guess I'll pony up for a new piston and compression tube and have a play around..
As far as I can tell buttoning does nothing other than make the thing feel smoother during cocking, and does nothing to affect the firing cycle and it feels pretty smooth as is so I'm happy there.
Back when I was a lad we used to guess at velocity with how clean the hole a pellet would make through a tin can. I use a chrony now
If you have the lathe etc.
You may consider removable / variable size orifice in the compression tube. Say, nylon locking set screws with through holes? McMaster Carr.
Maybe a variable length piston by threading the piston rod and putting a female threaded section in the piston body.
Keep in mind the cocking lever will only allow for a little more reward motion.
In other words.... start on paper or mock it up while the spring is out.
I would look at spring rate and compression tube orifice size first as they would have the least impact on existing design.
Have fun, best of luck
Shawn
You may consider removable / variable size orifice in the compression tube. Say, nylon locking set screws with through holes? McMaster Carr.
Maybe a variable length piston by threading the piston rod and putting a female threaded section in the piston body.
Keep in mind the cocking lever will only allow for a little more reward motion.
In other words.... start on paper or mock it up while the spring is out.
I would look at spring rate and compression tube orifice size first as they would have the least impact on existing design.
Have fun, best of luck
Shawn
Hi Shawn
Thanks for the reply, increasing the stroke and the swept volume are what I'm looking to achieve so more power and still be decent to shoot. I know venom used to do a longer stroke high power kit but trying to find information on how to recreate one is hard now they are no longer available, for some reason there seems to be an information blackout on tuning air rifles for power. I know it's a balancing act and just chucking in a huge spring isn't the answer, I guess I'll pony up for a new piston and compression tube and have a play around..
As far as I can tell buttoning does nothing other than make the thing feel smoother during cocking, and does nothing to affect the firing cycle and it feels pretty smooth as is so I'm happy there.
Back when I was a lad we used to guess at velocity with how clean the hole a pellet would make through a tin can. I use a chrony now
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