HW45 Poor performance. Is there a service guide?

[Jweaver]

Since I am sending my Combro chrono off for a service today, I decided to test my HW45, after all, if I 'missed' and broke the chrono, it wouldn't be an issue as they replace all of the broken bits for a flat fee (£7.50).

I was disappointed that it only shot 467fps (verified over 3 shots), with an 8 grain pellet, which by my calculation is 3.8ft/lbs.

I have a Polish Chrono on order, so will be able to verify the result, but I am pretty sure its right.

What can I do to restore the power? Is there a guide showing how to strip/service the gun?

Jon

[joffy]

http://www.airgunbbs.com/showthread....-with-pictures

[Jweaver]

http://www.airgunbbs.com/showthread....-with-pictures

Perfect.. I did a lot of searching and couldn't find anything.. Missed the vital words "strip down".. Cheers.

Before I go too far, is there any "maintenance" I could/should do (i.e a spot of oil)?

[ejackyou]

What calibre is yours, if its a .22cal that's very good performance for a 45
Some recommend dry firing the gun twice Only, when new, to set the Teflon seals
I shot mine into some padding to dampen it a little.

[Josie & John]

Mainspring main be broken, especially if the cocking stroke sounds graunchy or less robust than it used to be.

Or it may be something simple such a worn or damaged breech washer. Worth checking both before you get the tool kit out.

Finally a really daft question: Some pistols have 2 power settings. Are you positive you are fully cocking the pistol?

John

[Jweaver]

What calibre is yours, if its a .22cal that's very good performance for a 45
Some recommend dry firing the gun twice Only, when new, to set the Teflon seals
I shot mine into some padding to dampen it a little.

Its a .177, so a bit low... Funnily enough, it was dry fired last week by my friends by accident.. But I hadn't Chrono'd it before, so I don't know if this did any good, or harm.

[Jweaver]

Mainspring main be broken, especially if the cocking stroke sounds graunchy or less robust than it used to be.

Or it may be something simple such a worn or damaged breech washer. Worth checking both before you get the tool kit out.

Finally a really daft question: Some pistols have 2 power settings. Are you positive you are fully cocking the pistol?

John

Defo on full power.. Cocking feels normal.. But in truth, I bought this 2nd hand from a guy at my club, so I didn't know any different.. I don't know how much use its had.. But personally, I have only shot 100s pellets or so...

I will do some inspection before I get the tools out (And will wait till I get my new Chrono just to be sure).

Jon

[ejackyou]

I don't know where your located but perhaps your gun is one tamed down for some markets like mine, Canada where the legal limit
is 500fps. Like I said ,my .22cal HW45 gets anywhere from 410-467fps, my HW75 .177cal only gets up to 360fps.
Try a lighter pellet for more muzzle velocity?
I wouldn't consider at your guns performance, that it would be defective in any way?

[arsefactor]

Re : cocking position

If you have a dual power HW45 then the cocking arm has two locking positions.
On low power, it cocks at about 90 degrees, on full power you pull it further round, nearly 180 degrees fully open.

If you can only go straight to the almost 180 degrees position, you have a single power model. As said, unless it's an import it should be 'full power'.

I've had both a .22 and .177, both developed 5ft lbs measured over a chrono at full power.
Nice pistol by the way, worth learning to shoot right.

[ejackyou]

Yes thanks, I realise that there are two power levels.
In fact a Weihrauch technician told Tom Gaylord @ Pyramid Air, never to use the lower power on the HW45, always fully cock,
or your gun will eventually lose some power?

[Jweaver]

I don't know where your located but perhaps your gun is one tamed down for some markets like mine, Canada where the legal limit
is 500fps. Like I said ,my .22cal HW45 gets anywhere from 410-467fps, my HW75 .177cal only gets up to 360fps.
Try a lighter pellet for more muzzle velocity?
I wouldn't consider at your guns performance, that it would be defective in any way?

I am in the UK, and we are allowed 6ft/lbs, so at 3.8 I think its not right...

Are you saying that in Canada, you are limited to FPS, not Energy? How does that work?.. You could put a heavy load in a powerful gun and still be under 500fps, even though you have a HUGE (lethal?) amount of energy... Do they literally only limit muzzle velocity? Or is this at a specific projectile weight?

I am not too worried about velocity.. Of course I could go for a lighter pellet if I wanted a faster shot.. But I want to be sure that its delivering the correct amount of power and if its not fix it.

In a way I hope that my new Chrono confirms my findings as I would like to take the gun appart anyway, to learn how to strip it and fix it IF something is broken.

Jon

[Rickenbacker]

Just a note: Its really easy to mark the main crosspins and even the frame of the pistol - if the pins are tight, and if you don't have concave pin punches to match the convex ended pins.

[Rob M]

I've owned 2 HW45s, and seen more at the club, and around 4.5 ft/lbs is typical from what I've seen, so yours isn't that low really.

[Jweaver]

I've owned 2 HW45s, and seen more at the club, and around 4.5 ft/lbs is typical from what I've seen, so yours isn't that low really.

Got my new Chrono today.. Tried 1 shot and got 476fps, so its roughly the same as my Combro.

So its a bit down.. Just got to decide whether its worth the effort of stripping it now...

Thanks for your help.

Jon

[Jweaver]

I did a bit more testing over the weekend.. I noticed that the spring appears to be caked with grease.. So I blew it out of the gaps in the spring with my compressor and also added a spot of oil on the piston just to see what would happen.

I managed to get the speed up from around 470 to 490, so I think a good clean is in order... So my plan this week is a strip, clean and grease. But I wonder if its worth changing the spring and even piston seal whilst I am at it?

I found a link to a serial number checker and realised that my HW45 is a lot older than I thought.. It literally as new, but it could be over 20 years old..

How can I tell if the spring/seal needs to be replaced once I strip it?

Jon

Edit: Actually.. By my sums, (490x490x8)/450240 = 4.266 ft/lbs, which is almost exactly what Rob said above.. So perhaps I am wasting my time trying to get an extra ft/lb out of it...