Author Topic: Spring air rifles  (Read 15816 times)

Offline doubleboost

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Spring air rifles
« on: January 08, 2011, 04:25:49 PM »
Hi
Is anyone up to speed on tuning air rifles
My son has a bsa 22 that is way down on power
John

Offline Jonny

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Re: Spring air rifles
« Reply #1 on: January 08, 2011, 05:03:30 PM »
Depends what you mean by tune, most if not all are just a spring replacement, seal, under body car sealant and grease.
Even the world renowned pros use a form of sound dampening but this poses a few problems with power. Usually take time to warm up to reach max power, so many shots on then goes down in power.
Likewise cold it will shoot lower power, ot higher power.

Not a master but took my old mark 1 TX200 in to what was the old Venom shop 17 years ago.
Came away with a HW power pulse seal and modded piston to accept it.
Whilst there one served me went in back whilst the other two came out for a look - Within 3 months the Ultraglide was released!

Nothing new here but bored out end block and swaged spring guide in to it. Guide accordingly sized so that the spring had to be expanded and twisted on, no one to date has done.
Apart from the normal bearings and weights on guide and in piston no lubricants used! No grease nothing - not a hint of resonance but more so speed went up a good 70ft/sec and stable over a wide temp range.

There are a lot of misinformed falasies all copying each other like lemmings and getting no where. Delrin spring guides is one.
 
Which BSA you got?
I have a Goldstar from 94 duly shortened collecting rust the last 17 years, TX above is show grade in bits took apart to make an anglo US rifle and need to put back together 10 years on.

Offline doubleboost

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Re: Spring air rifles
« Reply #2 on: January 08, 2011, 05:19:56 PM »
It is a bsa lightning
I have been looking around the web at gas struts
But with the machinery at my disposal i am sure i could cobble something up
Has the transfer port size much bearing on things
John

Offline Jonny

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Re: Spring air rifles
« Reply #3 on: January 10, 2011, 04:56:58 PM »
Its been a long time but did experiment with interchangeable screw in sleeves on an HW80, around 1991.
Think the min was 2.5mm p to 1/8" - 3.5mm showed no gains and piston started slamming down.


Offline doubleboost

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Re: Spring air rifles
« Reply #4 on: January 11, 2011, 04:38:35 PM »
I took it apart and found the spring was broken in to 3 pices .
I polished the cylinder made a new guide tube cleaned all the burs and score marks up.
New seal and spring some drive shaft grease .
The change is amazing nice and smooth with plenty of power (i managed to restrain myself from fitting piston weights and spacer washers).
as it is it will be pushing the legal limit
Playing with this has wet my apatite i am starting to fancy a HW80 (that seems to be the spring gun to tune)

Offline Jonny

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Re: Spring air rifles
« Reply #5 on: January 13, 2011, 09:17:47 AM »
Nah get an older Diana/Original 52 :bow:

Offline GerryB

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Re: Spring air rifles
« Reply #6 on: January 19, 2011, 02:03:56 AM »
G.Day all.I remember in the late 1940s early 50s i had a BSA .22 based on the Lincoln-Jeffreys air rifle.
It started to loose some power so the local iron monger sold me a pair of springs.
My Farther made a screw driver from the poker as we had to go down a hole the length of the Butt in order to remove the breach from the butt.
After a lot of swearing and that the new springs were fitted.
Oiled up and leaning the Rifle against the shed wall in order to get enough purchase on the loading leaver it was loaded and ready.
I placed a tin can on the top of a small box in front of the dust bin.
Took aim and wow it not only put a hole through the can but also into the Dust Bin.
It Dieseled quit a lot of the time.
I went back to the Iron Monger and told him what had happened.
He said that the springs were Morris 8, Exhaust Valve Springs that he had got from a Birmingham Salesman.
GerryB

MrFluffy

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Re: Spring air rifles
« Reply #7 on: January 19, 2011, 07:14:27 AM »
Go for the hw80... I had a hw80e that had been fettled by a friend. When I bought it ex the local gunsmith's who had tuned it, it had LOTS of recoil, made a big thunk noise, and was down on power. He took it away and I paid him some money and it came back with a ticket saying 24ft/lbs on the chrono, had almost no recoil and a LOT quieter. I asked him what he did and he after some coaxing said that he'd fitted what amounted to the venom lazerglide conversion but without the fancy stock.
I had to stop using promethius nylon pellets because it used to blow the insert out the middle and leave the nylon flight inside, until they came out with the high power barb'd version.
Fantastic gun for rabbiting, very repeatable and my only complaint if you do is that they are LONG if you do a spot of shooting from moving vehicles. For that you would want the 80k version. The poachers choice :D ...

Ive got a recursive bow nowadays...

Offline doubleboost

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Re: Spring air rifles
« Reply #8 on: January 19, 2011, 11:58:32 AM »
Just bought a 80 k
Nice rifle if a bit heavy
Any advice on tuning would be helpfull
John

Offline Jonny

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Re: Spring air rifles
« Reply #9 on: January 19, 2011, 07:06:08 PM »
Want it to shoot good and legal, well as a springer any way.
Sleeve the bore down and use the older not the newer HW77 seal or locally made Power Pulse seal Venom used together with a better light weight piston with bushes, alum ok. Titan XS spring, bearings, tight spring guide swaged in to end block.
If youve made it right with correct tolerances there will be no twang so no underbody car sealant to damp the resonance and power all these tuners use. No grease or lube, it wont need any if made out of steel- metal on metal slides well with close fits, it dont slide too well when sloppy.

Gave my 80 away in 98.

Offline doubleboost

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Re: Spring air rifles
« Reply #10 on: January 20, 2011, 07:14:19 AM »
Thanks for that is bronze good for a spring guide
Nice and tight inside the sprina as it expands when compressed i asume that is the idea
John

Offline Jonny

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Re: Spring air rifles
« Reply #11 on: January 22, 2011, 06:21:42 PM »
Use steel polished up so that the spring wont go on unless its twisted and compressed by hand.
Make it a one piece, can add a bearing but limted to the cross pin in the Beesa. The guide could or would deflect in a vertical movement still. If yo can stop this could see gains of 10%.

 

Offline keithomas

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Re: Spring air rifles
« Reply #12 on: May 07, 2012, 07:12:44 AM »
i "tune" or "play" with hw80s. their an easy thing to squeeze more power out of. over 12ftps is illegal, your ass is going straight to jail if your cought with it.  got a couple of interesting builds on at the moment. one has a 30mm internal scrape out. sides are now parallel. the piston has been chopped down and delrin buttons. the 30mm parallel sides with the delrin buttons make it silent and no lubrication will be needed. its also got delrin piston guide which is mated in to the back end , delrin twist washer and delrin top hat.the piston also has a ptfe sheet in it to keep the metal noise down. I've all the bits to finish it but, I'm in the middle of building a workshop so all my toys are on hold

Offline Jonny

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Re: Spring air rifles
« Reply #13 on: May 07, 2012, 02:49:19 PM »
Junk the acetal, it flexes and worthless for its intended purpose.
the only reason acetal is raved about and used, think logically and between the lines. Its marketing! As in 5 min job as a one off for an HW80 in delrin, but same machine using steel looking at 1 1/2hrs, see where i'm coming from people are mugs and believe the marketing.

Then add delrin isnt stable in size, has more grab therefore more friction as the spring gouges in to it with greater surface area.
Prone to breaking as well, certainly with 10mm+ bore and 13.5mm+ o/d = 1.75mm thk wall 2.1mm tops!
Then add it flexes not keeping spring in a straight line, what you dont want.

Steel would have less friction due to lesser surface area and coeficient of friction any way. You tried moving a ton machine digging in to soft material such as wood or delrin, it dont slide. Using steel to steel machine slides easilly, similar to the compressed spring wanting to buckle or veer off!
Anyone with any engineering practice will agree to highest level.

Offline doubleboost

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Re: Spring air rifles
« Reply #14 on: May 07, 2012, 03:34:09 PM »
Hi
I made a spring guide for my HW 80 out of a bit of en8
It was a tight fit on the spring (screw on tight)
Taperd the transfer port polished the piston and honed the cylinder
I had to cut 3 inches off the spring to get it legal
Now it is a dream to shoot
Very easy to cock smooth and quiet giving a constant 11.5 ft lbs
It was well over 25 with a Webbley venom spring before i cut it
John

Offline Jonny

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Re: Spring air rifles
« Reply #15 on: May 09, 2012, 03:19:36 PM »
Thats the way it should be John, other people cant grasp the concept or logic.
By keeping it tight and where delrin flexes off, steel keeps it straight in the direction of energy released.

Understand these tuners, they use springs locally  made on a mandrel, nothing dimensionally accurate and have to fit all diameters. Of course this then gives off the twang and to combat that coat the spring with underbody car sealant or Rocal gear stuff to absorb this resonance. In doing so absorbs power or energy transmitted.
Whos fooling who, people are mugs paying for bad workmanship and raving about it after.


Offline keithomas

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Re: Spring air rifles
« Reply #16 on: May 15, 2012, 04:34:00 PM »
im guessing your a shooter then johnny?

Offline S. Heslop

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Re: Spring air rifles
« Reply #17 on: January 11, 2014, 12:37:57 AM »
Just got myself a SMK B2 at a second hand shop. It's hard to tell if it's me or the rifle but I didn't have much luck consistently hitting a few cans at the bottom of the garden. It's smoking from the barrel after a few shots (dieseling?) and a few of the fired pellets I found were squashed on the side, which to me suggests that they could be tumbling in flight. I might try hitting a steel plate perpendicular tomorrow (with eye protection at least!) to see how that turns out.

Any suggestions on how to reduce the power if this turns out to be the case?

Also what kind of oils are best used in these things? I tried finding this out via google but all I found were crap forums full of 'experts'.

Offline mcostello

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Re: Spring air rifles
« Reply #18 on: January 11, 2014, 10:04:29 AM »
I am a lurker from the USA. I was wondering how anyone would know if anyone's air rifle was too powerful. Does someone come around and check these things or taken in for license? We don't have similar laws here.
High Speed steel in a Carbide world.

Offline NeoTech

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Re: Spring air rifles
« Reply #19 on: January 11, 2014, 03:01:02 PM »
Build him a PCP rifle.. Its not that hard and dont make use of springs for pressure. =)

Get the book from H.M Buckley "The modern pneumatic airgun"
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline Jonny

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Re: Spring air rifles
« Reply #20 on: January 11, 2014, 05:10:04 PM »
I am a lurker from the USA.

Its up to the owner and the person in possession of said air rifle to make sure its legal. Over here that's 12ft/lb energy.
Over 12ft/lb its classed as a section 1 firearm which licence has to be granted much the same way as any rim or centrefire rifle.

Neo the Buckley book waste of time and money, its 30+ years out of date old hat even though written in recent times last 10 yrs. You will learn a lot more than any book will teach and understand more if you take the 'deep end' In other words fresh look, no copying other mistakes work it out for yourself, its not rocket science.
Theres a big difference between making something copying others to making a one off design down to the last screw including working out the leverages for proper two stage triggers. Single stage anything will do, most cheapies are.

Offline Manxmodder

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Re: Spring air rifles
« Reply #21 on: January 11, 2014, 09:44:17 PM »
Thats the way it should be John, other people cant grasp the concept or logic.
By keeping it tight and where delrin flexes off, steel keeps it straight in the direction of energy released.

Understand these tuners, they use springs locally  made on a mandrel, nothing dimensionally accurate and have to fit all diameters. Of course this then gives off the twang and to combat that coat the spring with underbody car sealant or Rocal gear stuff to absorb this resonance. In doing so absorbs power or energy transmitted.
Whos fooling who, people are mugs paying for bad workmanship and raving about it after.

Hi Jonny and Double Boost
Don't know if you're still reading this thread as your last posts were back in mid 2012.

Jonny makes some interesting observations about the quality and consistency of some tuners mandrel wound springs.

A long time pal of mine and partner in many crazy engineering projects over the years is also a gunsmith and an avid competition shooter of air weapons and full bore pistol.

We were recently talking about the effects that spring accuracy has on target grouping consistency and discussing the possibility of using square section cnc machined coil springs.

This route may sound a bit over the top and excessive but comp shooters are always looking for that extra degree of performance.

I just wondered if any of you guys on here had ever seen this type of spring used in an air weapon and if so how did it perform?

Here below is a link showing a photo of the type of spring I refer to:
http://cfnewsads.thomasnet.com/images/large/005/5086.jpg

Bye for now ,OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline Jonny

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Re: Spring air rifles
« Reply #22 on: January 14, 2014, 11:25:53 AM »
Oz new one on me. Cant quite make out whether that's an air operated strut if you like or a machined from solid pitch to create a compression spring. Either way no good and disadvantageous both on multiple counts.

If its air filled or even a gas, it will be affected by temp then have that horrendous harsh recoil that breaks scopes.

If machined from solid the grain structure is not in the direction of the helix. Normal compression springs are from wire with the grain structure running the length. V springs well proper made ones should be turned (forged, folded, hammered) then opened out after and annealed = more strength.