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PostPosted: Fri Jul 28, 2017 10:35 am 
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Joined: Mon Aug 15, 2016 10:12 pm
Posts: 34
Location: Toronto, Ontario
Hey all,

Been testing my P1 .22 with a Chrony, and lately found that velocity has been decreasing as I continue shooting.

With 20 shots using Hobbies it would start at 465-475 fps, then gradually drop to around 435-440, and then fluctuate in that area.

The next day it would do the same thing. It's like the gun sleeps it off, lol. I get extreme spreads up to 40 fps.

Would this be some quick easy fix? I've put around 1300 pellets through, haven't done any sort of maintenance to it at all.

Thanks,


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PostPosted: Fri Jul 28, 2017 12:24 pm 
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Location: Bradford
Probably not much help, but perhaps something is getting warm, expanding, and losing seal.

I know in a way that doesn't make sense...if it expands the brain says it should fit tighter, but thats not always the case...maybe the metal around one of the O-ring seal areas's is getting warm for example and the O-ring becomes "just" loose enough to let air go past.

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Fri Jul 28, 2017 1:22 pm 
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Joined: Mon Aug 15, 2016 10:12 pm
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Location: Toronto, Ontario
Yeah, weird!

I've searched the web on this issue. Found nothing.

The only visible difference from the time I bought this gun to now is that the O ring seal looks dry whereas before it was covered with oil. I presume that would be silicone oil?

May have to get one of those and re-oil the seal to see if that would fix the issue. Unless there are others who have experienced this have other tips.


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PostPosted: Fri Jul 28, 2017 1:52 pm 
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Location: Ontario, Canada
You might need to lube the power plant. Try applying a pea size gob of moly paste through the cocking slots and onto the mainspring (simple slot tune). It's easier to do when the top half of the frame is removed to expose the open spring coils. Also try changing your breach seal (#009 nitrile o-ring). You could also try shimming your breach seal with several wraps of dental floss under the seal.

I'm not sure if this link will work for you. If not, PM me your email address and I'll send you the files from my old HW45 Review.
http://web.archive.org/web/200409082023 ... W45Review/


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PostPosted: Fri Jul 28, 2017 5:07 pm 
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Location: Burlington ON
Weihrauch owner's forum is quite good if you don't get to the bottom of it here.


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PostPosted: Fri Jul 28, 2017 9:00 pm 
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Location: Bradford
Another train of thought....it might be dieseling the first few shots and thus giving you inflated velocity numbers, then after the oil burns off, the velocity goes back to normal.

Put the gun away and let it rest, oil seeps back in to the compression chamber and the process repeats.

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Fri Jul 28, 2017 9:57 pm 
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Location: Toronto, Ontario
TCooper wrote:
You might need to lube the power plant. Try applying a pea size gob of moly paste through the cocking slots and onto the mainspring (simple slot tune). It's easier to do when the top half of the frame is removed to expose the open spring coils. Also try changing your breach seal (#009 nitrile o-ring). You could also try shimming your breach seal with several wraps of dental floss under the seal.

I'm not sure if this link will work for you. If not, PM me your email address and I'll send you the files from my old HW45 Review.
http://web.archive.org/web/200409082023 ... W45Review/


Thanks man, the link works. You seem to know all there is about this gun. Will read whenever I get a chance. Also, I wish my P1 was as well tuned as your 45.

ITGUY wrote:
Another train of thought....it might be dieseling the first few shots and thus giving you inflated velocity numbers, then after the oil burns off, the velocity goes back to normal.

Put the gun away and let it rest, oil seeps back in to the compression chamber and the process repeats.


435-440fps range with Hobbies would be considered very low for a P1. I hope that's not the normal, otherwise there's a bigger problem somewhere.


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PostPosted: Sat Jul 29, 2017 2:07 am 
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Next time you shoot the gun, wait until the velocity stabilizes then put a couple of drops of silicone oil in the compression chamber and recheck velocity. If your piston seal were bad for some reason, the fresh oil might increase the velocity for a few shots.

As well, if the gun was dieseling, the silicone oil should stop it from doing so and that would be easily noticed the next time you take it out and shoot it.

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Mon Jul 31, 2017 11:59 pm 
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Location: Toronto, Ontario
ITGUY wrote:
Next time you shoot the gun, wait until the velocity stabilizes then put a couple of drops of silicone oil in the compression chamber and recheck velocity. If your piston seal were bad for some reason, the fresh oil might increase the velocity for a few shots.

As well, if the gun was dieseling, the silicone oil should stop it from doing so and that would be easily noticed the next time you take it out and shoot it.


How do you get silicone oil into the compression chamber without disassembling the gun? I'm having hard time finding where the drops should go, even in a cocked position.


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PostPosted: Tue Aug 01, 2017 12:18 am 
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vortex619 wrote:
ITGUY wrote:
Next time you shoot the gun, wait until the velocity stabilizes then put a couple of drops of silicone oil in the compression chamber and recheck velocity. If your piston seal were bad for some reason, the fresh oil might increase the velocity for a few shots.

As well, if the gun was dieseling, the silicone oil should stop it from doing so and that would be easily noticed the next time you take it out and shoot it.


How do you get silicone oil into the compression chamber without disassembling the gun? I'm having hard time finding where the drops should go, even in a cocked position.


I don't have the exploded view in front of me, but would some oil down the barrel not seep in to the compression chamber through the transfer port?

That's what I was thinking when I wrote the idea anyway.

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Tue Aug 01, 2017 9:42 am 
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Mix a drop or two of silicone oil with a small gob of moly paste and apply a thin layer to the exposed mainspring and what you can see of the piston body. If you remove the upper frame half (pop out pivot pin) then you can work some lube between the spring coils with a paperclip. Shooting the pistol will distribute the lube. This is called a "slot tune" and it's an option for those who are not inclined to disassemble. The HW45/P1 does well with a small amount of lube. If you overlube, it will slow down for a while. Been there.

As mentioned, check your breach seal. They are cheap #009 nitrile O-rings that you can get at a hydraulics shop. Get a bunch and test velocity. Also try a dental floss shim. This sort of experimenting gets you some almost free velocity. A skinny or nicked or worn seal can cost you speed. Carefully pick out the old seal with a pin and pop in the new one.


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PostPosted: Tue Aug 01, 2017 10:22 am 
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Joined: Fri Jul 01, 2016 7:47 am
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Location: Bradford
TCooper wrote:
Mix a drop or two of silicone oil with a small gob of moly paste and apply a thin layer to the exposed mainspring and what you can see of the piston body. If you remove the upper frame half (pop out pivot pin) then you can work some lube between the spring coils with a paperclip. Shooting the pistol will distribute the lube. This is called a "slot tune" and it's an option for those who are not inclined to disassemble. The HW45/P1 does well with a small amount of lube. If you overlube, it will slow down for a while. Been there.

As mentioned, check your breach seal. They are cheap #009 nitrile O-rings that you can get at a hydraulics shop. Get a bunch and test velocity. Also try a dental floss shim. This sort of experimenting gets you some almost free velocity. A skinny or nicked or worn seal can cost you speed. Carefully pick out the old seal with a pin and pop in the new one.


Although not the original poster, I appreciate the info. I have no qualms about disassembling one of them, but if I dont need to.....one of the HW45's is on my short list from D&L, just not sure which one yet. I am a sucker for laminate, so maybe the Black Star in .177

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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