Hw45 low power

[peddy]

When I stripped mine it had thick factory grease which I've removed and used LT2 light coat of sm50 on the piston seal. New breech seals are on there way will fit one and refit barrel and give it a try. Has anyone else replaced the other two o rings because they were duff, can't decide what to do about them.

[Bruno27]

When I stripped mine it had thick factory grease which I've removed and used LT2 light coat of sm50 on the piston seal. New breech seals are on there way will fit one and refit barrel and give it a try. Has anyone else replaced the other two o rings because they were duff, can't decide what to do about them.

If you have any doubt replace them. I will take mine apart tonight.

[Bruno27]

I just have taken my 1992 .177 HW45 to bits.

Before, I measured speeds with 10 H&N "special club" starting at 527 fps (4.57 ftlbs) and regularly decreasing to 501 fps (4.13 ftlbs) Thinking about it, I should have tried more pellets to see how far down it would have gone. Temperature was 16 C°.
Found the spring a little bent which is to be expected with such a big length to OD ratio. So spring is 223 free length, 34.5 total coils, 11.95 ID and wire Ø 2.39. All with a fair amount of lube but none ahead of the piston seal.

I found the larger oring (OR061) on the cylinder end block badly damaged. I don't understand why as it is static and I have a good reason to believe that the gun has never been taken apart. The smaller oring (OR060) on the breech block is ok.

The piston was extremely tight due to the seal, and I wonder if anyone has seen this before? I am very familiar with the Webley Tracker using a similar system, but never seen a piston seal that tight.

I would like to gain a consistent 60 fps which would take the gun to just under 5,5 ftlbs. I wouldn't even think about a hot HW45 as I feel it isn't realistic.

I will spec the orings tomorrow and I will let you know of my progress.

[peddy]

I just have taken my 1992 .177 HW45 to bits.

Before, I measured speeds with 10 H&N "special club" starting at 527 fps (4.57 ftlbs) and regularly decreasing to 501 fps (4.13 ftlbs) Thinking about it, I should have tried more pellets to see how far down it would have gone. Temperature was 16 C°.
Found the spring a little bent which is to be expected with such a big length to OD ratio. So spring is 223 free length, 34.5 total coils, 11.95 ID and wire Ø 2.39. All with a fair amount of lube but none ahead of the piston seal.

I found the larger oring (OR061) on the cylinder end block badly damaged. I don't understand why as it is static and I have a good reason to believe that the gun has never been taken apart. The smaller oring (OR060) on the breech block is ok.

The piston was extremely tight due to the seal, and I wonder if anyone has seen this before? I am very familiar with the Webley Tracker using a similar system, but never seen a piston seal that tight.

I would like to gain a consistent 60 fps which would take the gun to just under 5,5 ftlbs. I wouldn't even think about a hot HW45 as I feel it isn't realistic.

I will spec the orings tomorrow and I will let you know of my progress.

I can't quite see how the larger o ring comes out, if I've to take that snake of a spring out again don't think Il bother. My piston was tight also getting out and in, much more than last few rifles I've stripped down, put it down to little use over past 20years. Yours wasn't consistent before strip whereas mine had extreme spread of only 9fps over 10 shots, which from experience indicates no seal damage? Did you undo the bolt on top of the cylinder to inspect the smaller o ring?

[Bruno27]

Did you undo the bolt on top of the cylinder to inspect the smaller o ring?

Yes peddy, and this is why you need to remove the end bloc to get to the larger oring

[peddy]

Thanks bruno27, assume that means the mainspring has to come out again? Let us know the outcome of yours? Like you said I'm surprised that larger seal was damaged when its static!

[Bruno27]

... assume that means the mainspring has to come out again? ...

Free the hole on the spring retainer by moving the pin out of the way then stick a rod or a pen in the middle to use as a guide, works a treat.

[peddy]

Free the hole on the spring retainer by moving the pin out of the way then stick a rod or a pen in the middle to use as a guide, works a treat.

Hmmm any chance of a pic?

[peddy]

Just an update from my original power problem. Ive stripped it completely except for the two hidden o rings as I wasn't confident doing so! Replaced breech seal with a 009 o ring, polished the spring guide and spring ends and piston body. Degreased everything and relubed the spring, guide and piston body with LT2, smear of SM50 on piston head, used same spring, reassembled.

The spring was a little bent
The piston head was a tight fit
The original factory grease was very thick

Original average over 10 shots 310fps 3.0fpe with superdomes
Now averaging over 10 shots 409fps 5.4fpe again with superdomes, extreme spread of 8fps, no hint of dieseling and less recoil.

An amazing result from little expense,

[Bruno27]

Good result Peddy
I have replaced all orings on mine with only a very small power improvement and power not falling down.
I measured the force required to move the piston at ~15N, so very tight indeed.
I put it back together as it was, just a rough clean and no lube.
I will follow your route and see what happen.
I guess you now master the spring removal and fitting.
Did you put the spring guide at the piston end?

[peddy]

No didn't put spring guide piston end. Even with spring compressor I struggled lining the end cap up and it was a tight fit, done much bigger springs much easier! My old breech seal looked fine so reckon the big jump in velocity is down to getting rid of factory grease and polish and relube especially the piston head. Thanks for your input, nice to get a good result, had a lot of fun at the club Saturday with it.

[Bruno27]

No didn't put spring guide piston end.

So, and as I understand, you loose a bit of power and gain on a smoother shooting pistol. Can you confirm?

[peddy]

So, and as I understand, you loose a bit of power and gain on a smoother shooting pistol. Can you confirm?

I've gained all round bruno27, around 100fps increase a lot smoother and less recoil. I think the piston head needs lubing on yours, mine went back in much easier with sm50 on it. Though yours is pretty good for a .177 and if the power has stopped dropping, the new seals have worked.