Tuning My Walther lp53 upgrades

[Townsniper]

Hello dear 

Here what I have did to my Walther lp53 to improve accuracy and power 

Thank you 

 

[Steveoo]

It is a nice effort fella but your piston head is robbing you of valuable stroke. Not only in the fact that your O ring has too much land before the groove starts, but also the thickness of what is to the rear of the O ring.

The real power can be achieved when the entire seal is kept to a max of 8mm …only leaving about 2mm of cocking slot left, but just enough to be safe, while giving the maximum stroke. Also try to flatten and polish the end of your mainspring, it will cause rotational torque left sharp like that.

Nice effort with your Delrin guides, pretty much replicating how i went.

 

[Townsniper]

I will upload all the dimensions of the head seal inorder u can tell me what is in need to be adjusted .

I will try to may the end of the spring more flat and smooth 

The main issue that I have faced after these changes is the low shooting group, around 7cm below the point of aim over 10meter distance so replaced my rear sight adjusting vertiscrew with more longer one inorder to be able to rise the the rear sight up ! 

Also some scattered, non grouped shots were noticed after these changes! 

 

[Steveoo]

With all that lost volume, you probably have a stroke not much more than 40mm, but it should be more like 50mm.

Pellet choice.?…you would def require a fast start pellet.

 

[Townsniper]

I can't understand what's meant by that my stroke is 40mm not 50mm

Here are all the dimensions of my upgrades 

Waiting to hear your comments steveoo

Here how I tried to fix the low grouping by using a taller screw

Here the pellets I use 

 

[Steveoo]

Your piston head is near 11mm …it needs to be 8 mm…...the extra 3mm of stroke length is vital…as is the volume…more peak pressure ..

Your pellets should be fine. That angled spring end must be causing huge rotational drag/ torque

 

[Townsniper]

Here more accurate photos before reducing the height of the pistol seal head from 10mm to 8mm 

Here also how I replaced the keyed way with a screw to keep the head seal in place and it works well after 250 shot

 

[Steveoo]

You still have a significant amount of lost volume where the screw fits. You could afford this screw to be almost flush. As long as it sits below the head of the piston head by a few, it should not hit the bottom of the piston chamber. So i would skim a good bit more material off that front face.

 

[Townsniper]

I will try to fix the point of the screw in the adjusted one that I'm going to make 



I want to ask if my main spring seems to be short ? That may lead to weak and slow push ? Or it's fine that way ?

Note: already I have flatten it's end but I didn't take a new photo

Will it help if I make the upper spring cap from a metal instead of PTFE ?

 

[Steveoo]

Make the spring flat…do not worry its a little short, you can simply replace lost spring length with a slip washer in Delrin

 

[Townsniper]

This is my new head seal

Still didn't try it ...

Regarding the slip washer u mean like this ?

Should I put it below the lower end of the spring or where ? And what is the needed thickness of the washer ?

 

[Steveoo]

Much better seal thickness now. This should give you close to the maximum you can make.
See if the slip washer will slip over the lower guide with the 11.70mm stem…
If not drop it down inside the piston with the Top hat on top of it…Do not put it over the OEM guide inside the grip cap as you will have metal on metal contact in your grip cap.

 

[Dmiowahawk]

Nice group, good work!!

 

[Townsniper]

Last results after head seal adjustment

 

[Steveoo]

If you know what you are doing, these things can really perform.
Working with either a Leather, or Red seal, providing total build up of the piston head unit/seal does not exceed much above 7.5mm, you can have 50mm of stroke x 23.1mm dia of piston chamber …which is more volume than a Webley Tempest, but with a more efficient in-line TP. So it can easily do 500fps with 8 grain pellets.
TP sleeved to 3.2mm, giving even more efficiency.

In addition, i honed out the cylinder until perfectly true and use fast start pellets …Falcon, or JSB RS.

 

[Steveoo]

Next one up is correct lubrication. You need to use Crosman/RWS Chamber lube which is pure Silicone.

You will have heard many incorrect comments regarding Silicone galling in airguns, everyone chiming in with don't use that it galls, but robbing shooters of the benefit of this lube.
The idea that this stuff galls is ignorance. I have used it since the 80s and never experienced galling, providing you use the correct grade (there are many grades) and use it correctly.
Pure silicone only galls when placed under high pressure load on say a breech face sliding into position under high load with the TP face, or a high load cocking pivot, with zero clearance between mating parts.
With the usual 0.2 to 0.3 clearance of a piston inside the piston chamber, it will not gall, and at the worst case, will merely hone the bore of the cylinder after many 1000s of shots, but it will keep that seal wetted, sealing and will not diesel. No other lube does that very well with seals, esp leather.

The rear of the piston, I wipe with a smear of moly, but i leave it off the spring, it does not need it if using delrin guides.