Tuning Walther LP53 Tune

Thanks guys....makes it worthwhile.

Cloudshe...sadly not as I am one of the few on here who is on British soil....However, if you need sizes to get the parts made up, I can supply.

The mainspring is an easy task if you need the instructions. Failing all this, you could get a kit shipped from Proteks, which followed my original design to some extent. It just needs a better mainspring, namely a HW35 spring, chopped to 18 coils and flattened on its cut end.

The main problem with the LP53 is seeking out a piston seal and getting it shipped. Its worth pursuing however, as a tuned specimen is one of the best pistols in the world once sorted...

I did not go the TR Robb route with his PTFE seal but you can. It gives about 500 fps when used in conjunction with my kit above, or about 40 fps over the stock Walther seal, but like all guns which use the PTFE head (Webley Tempest etc) there is too much slam because the seal eventually takes a set and is very temp sensitive. You can learn to shoot with the slam and temperature sensitivity of PTFE but it takes lots of practice. I simply found my own seal design can factor out the issues. Despite being a pistol marksman, I never got past the shifted group elevation of a Tempest, or Premier going from a Cold day to a warm one.

The route i went here is placing the rubber buffer unit within the Leather seal (sitting just proud) The Stock Walther seal placed the rubber buffer ahead of the leather which created lost stroke. Placing the buffer inside the leather seal, gave me 2mm more stroke, giving me 45 fps. The rubber buffer (as a material) was something Walther did get right, It does not expand the leather, unlike leather buffers which slowly deform the outer seal outwards until it gets too tight.

Forget more powerful springs, packing washers etc, the way to improve springer pistols is increasing the stroke, smoothing out the spring and reducing the TP diameter. All springer pistols benefit from having a TP not greater than 3mm. It just depends how difficult the reduction is for the 20fps gain and reduction in slam. While a well set up leather seal, like above, is hard to beat in a pistol. A lovely cushioned shot cycle and will last for years.

The Predom, can be modified similarly but I never fell in love with the gun enough to want to bother. The huge effort with the LP53 came about because i liked the gun.

Ok....The thing I would do, is get hold of a HW30 mainspring and crop it to 18 coils, then close the last coil flat with a blow torch. Easier than it sounds.

Then get a guide rod made with a 8.2mm hole drilled through it to fit over the stock guide. Failing this order the Proteks kit, chucking out the spring and replacing it with the HW30 spring as described above. Some wasted cost here but worth it and will last forever.

The key with any springer pistol is to get the velocity upto the magical 500 fps mark, which sees the pellet leave the barrel before the recoil starts and then not affecting the pellet flight. 

Grips maybe a problem. I have never seen any available. 

If you have gone for a leather seal like mine above, you need to soak it in Neatsfoot oil. Its intended for leather, will not rot the leather and as a bonus, does not diesel.

Look down inside the piston chamber and make sure the TP is clear. Clean out the chamber until it has a bright finish. I polished mine out using a 22.95 piece of turned Delrin with Auto sol on it. It gave me a perfectly true,,polished bore of 23mm. I then cleaned this out with bore cleaner.

The piston was then polished in the lathe. The inside of the piston is clean enough and just needs a clean. Seal is assembled after 24 hrs in the oil. However, before i soaked the seal i put the seal on its key hole mounting unit and put it into a drill chuck, polishing the seal with wet and dry paper, until a nice slip fit was achieved into the piston chamber. Then i soaked it. It did not expand during the soaking as it is quite a hard leather...maybe growing .004 max. You need to get your piston sliding up and down nicely anyhow. A touch of Moly to the rear bearing of the piston is all that is needed. The odd drop of Neatsfoot down the TP will look after the seal.

Mainspring and guides set can then be added. No need for grease, as the Delrin handles the bearing but i wiped a meniscus of oil to the outer of the spring where it contacts the piston.

The use of the Falcon, or AA Express pellet is quite vital for the pistol has a tight bore. The rifling is perhaps the finest of any air pistol but it is a touch tight. Make sure the O ring is not worn flat. You want a 6mm bore O ring with 2mm cross section. Any bog std nitrile O ring is fine. It is the easiest sealing set up i have ever come across on any pistol, 100 percent reliable for 10, 000 shots and is a perfect hermetic seal.

Clean the barrel and away you go. 

There is a big benefit to a TP reduction on this model but we will deal with that at a later date. 

Your piston seal and piston should end up looking like this before you put it in...Note the overall thickness of the seal should not be greater than 8mm as it will start to impact on valuable stroke and volume.

Yeah the 30 spring, which is the best spring you will find for this gun and a nice fit in the piston, without needing to sleeve. Practically indestructible. Cut it to 19 coils then heat the end and flatten it until you get 18 to 18.5 coils. The latest idea is to not quench, presumably to reduce the chance of making the spring end too brittle, but i have always quenched in oil. I have never had one break. Might be a hair-brain idea to not quench...too slow cooling and you might lose the temper, but do not quench in water...too fast and the spring will crack at the base.

Once flat, grind and polish the ends. Then remove all burrs inside the spring at this point, or they will cut into the delrin guide.

It sounds like you using wrong pellets, not sealing at breech, or piston seal to get slam like that. Get it running right you will get hardly any.

TP reduction is 2.8mm improves shot cycle no end and raises power but get the rest running right first.

The 53 requires great care and attention to get right but it rewards massive when done. Treat it as if doing an antique clock re-fit....I didnt know wether to laugh, or cry when Mileski ran his AGW magazine tune of this gun. There are crud tune parts and expert tuners!