Tuning Walther LP53 Tune

[Smooth-Operator]

Hello Steveoo, 

my name is Lennard and I am from Germany. So if my English isn’t as good, I apologize. With interrest I read about you‘re modifications you‘ve done to you‘re LP53. Also the fact, that you’ve shortened the barrel is very cool. Looks fantastic. I also have an LP 53 and would like to modify mine a little bit too. Except for the barrel cutting, because I‘m afraid of damaging it, although I would have access to a lathe.
So, from you‘re postings I already know, that I need a HW30 spring and cut it to 19 coils and then flatten the end. This is clear. Also the piston facts are clear, but how you reduced the TP from 4mm to 2,8mm? And what are the measurements of the Delrin Top head and the bottom guide rod? Also the fact that you use a picatinny rail an top is very interesting. I already have a rail that would fit the screw holes of the LP53 perfect ( I think it’s the same you have), but what screws do you use and were did you find those? I searched the web, but I couldn’t find any. I think they are M4 screws, but with a fine thread, because standard M4 won‘t fit and would destroy the threading. 

Would be great if you can help me and give me more informations about you‘re mods.

Thanks in advance. 

 

[Steveoo]

Ok buddy no problem...

First up let us tackle the rail. Any std. 5 slot rail will fit because the hole centres are the same, however, the screws do not fit because they are std. metric, but the Walther holes are metric fine. So i ordered a metric fine Die and it ran down the screws that come with the rail.

Go with 18 coils...

Top hat should have a seating rim of 4mm thick x 18.80 mm. Length of stem to go inside mainspring should be 12mm x 12.70 in diameter (push fit into HW30 mainspring) Hole drilled through needs to be 8.2mm to clear the stem of the piston nose unit. (8mm dia)

Rear guide needs to be 40mm of stem x 12.70mm) The location rim needs to be 18.5mm dia x 4mm long. Hole through the guide 8.2mm 

Finally, you can use telescopic radio aerial for making the TP sleeve, or turn 4mm diameter x 12 mm long and drive in from the breech face...

The TP hole needs to be a max diameter of 3mm.

You do not need to do this, but I also add a hardened steel slip ring down inside the piston to act as a thrust seating due to the offset key hole at the bottom of the piston not being the best seating for the top hat. With all that done, the gun will eliminate all felt torque and will rise 100 fps over stock with JSB RS 

 

[Smooth-Operator]

Thank you very much for you’re fast reply. That’s a good tip with the die for the screws. I didn’t even thought about that. Am I’m right, that the tube for the TP is just a press fit and not glued in or anything? Thanks for the picture and you’re help. I will try to do my best. 

 

[Steveoo]

I machined a stainless 4 dia length of bar, with a 3mm hole through it. Something like a slide fit, then gluing in with Red 638.

Degrease the OEM TP before gluing the new port in as all TP are oily from the cylinder....Do not machine the new port from Delrin like some do as Delrin cannot be glued successfully..

 

[Smooth-Operator]

Ok thanks for the tip with Red 638 for the TP and not to make it out of delrin. My new piston head with the leather seal now looks like this and weighs 19,04g. What rubber do you used for the piston or better asked from what is it made of? And why you placed it proud and not flush with the leather seal? To reduce slam? Reduce wear on the leather seal? And is the rubber on your picture curved in the area of the screw, because it is compressed by the screw or is it shaped like this? 

 

[Steveoo]

Buddy, Your piston head looks superb. I recommend you try it. Mine is potentially a weaker design (from the solid engineering point of view) but by having the steel holder and rubber buffer within the leather, it gives me a total build up of no more than 5/16” (8mm) thickness, and the maximum stroke I can realistic achieve to give the most power. I actually went down to 6mm thick but found i was perilously close to running out of cocking slot. These leather seals do compress a little and felt it too risky so i settled on 8mm.



The buffer is a std engineering shock absorber from a machine supplier. You could use anything which damps. 

My buffer appears very proud due to the angle of the picture but in reality is just the same as the leather, perhaps a few thou above but will compress more than the leather. It can do no more harm than help damp the shock on the leather, without stealing any stroke.

Measure your total build up height from front of piston face, it may rob too much stroke if above 3/8” (10mm) thick, but i like the look of it ..

You could stick with your design, and simply face off a 1/32 to 1/16” off the front face your steel adapter....but very Nice work. Well done.

 

[Smooth-Operator]

Thank you for you’re praise. Today I made a rubber buffer which fits better than the metal inlay from before. I see, you went for an other design for your piston head key hole adapter. The metal part goes inside the leather seal and the back of the leather seal sits on the top head of the piston itself. Very clever. I like it very much. So you’re total build up height for the piston head is thinner right away. Very nice. At this point I am at a total height of 10,47mm. My original Walther piston head has a total height of 7,64mm. So I will, as you said machine of 2mm of the front face of the adaptor, to come as close to the 8mm as possible.

I am still waiting for my delrin rods to arrive. Then I will make some tests and report the results.

 

[Steveoo]

Thanks...That will give you a much better damped cycle and no lost volume down inside the leather like you had.

The OEM LP53 head unit was was approx 8mm (as your 7.64) but it had a head buffer, with the sealing leather sitting to the rear of that.

So, although it was 2mm thinner than your seal, it still suffered from 3mm lost volume due to the thickness of that rubber buffer.

I still liked your metal seal. It maybe more robust, if a bit less in velocity.....I sent you a PM

 

[Luckyshot]

O.K. I give up, what is the trick to replacing the sear on the pistol? I can't seem to position it so that I am able to replace the pin. Thanks.

 

[Steveoo]

You need to drop the little anti bear trap lever forward of the trigger mechanism and pull the trigger....

I usually hold the trigger back with a rubber band around the blade of the trigger and going around the beaver tail.

This will then allow plenty of forward and back movement over the alignment hole....when it aligns quickly poke in a pin punch ....This will hold it aligned while you then tap in the pin from the other side. Much easier than trying to drive in the pin while trying to align the holes...

 

[Luckyshot]

Steefoo, you are correct about the TR Robb PTFE piston seal. I recently installed one in my LP53 and find its firing behavior much harsher than the original leather. I'm going to stick with it for now, but wish I would have gone with leather. Maybe I will eventually adapt to the harsh piston slam. The unit you fabricated looks to be a winner.

 

[Steveoo]

Pair of my latest seals. One in Stainless Steel and the other in Blacked high carbon steel...Leather is exactly sized for slide fit and the inner buffer is flush with the barest clearance on its diameter for a snug fit within the leather....to keep any lost volume to a minimum.

I made the steel component so it fits the key hole with zero slop to remove any chance of inconsistency, and power loss..

Stainless screws lock up tight, just below surface of the rubber....shown slightly proud in the stainless version, so you can see what is going on..

These seals really perform and are superb at cushioning the shot cycle...

 

[Smooth-Operator]

Hi Steveoo, buddy. You‘re new seals look fantastic. How do they perform? Which thickness you have chosen for the steel basement the leather sits on?

 

[Steveoo]

Cheers buddy, its 1.8mm Stainless Steel....

I am currently revisiting the Tony Leach seal and adapter which we developed together ....The guy who developed the Seamless piston.

The reason being that some shooters prefer the fact it does not require continual lubrication like the leather does...using his red parachute seal..

All seal produce 500 fps plus with my own design spring kit and reduced TP diameter..

 

[Luckyshot]

I like the idea of the rubber washer/shock absorber on your piston seal design. Seems like that would do much to mitigate the shock experienced when the piston slams into the top of the cylinder. Since the LP53 is intended to be a target pistol, any reduction in recoil is helpful. I don't know about the parachute seal setup, but I try to keep an open mind.

Fred.

 

[Steveoo]

The parachute seal design is supposed to flair open on shooting and the more the pressure increases, the more it opens, effectively cushioning the shot....Its marginally not quite as damping but ive been into 525 fps territory and single figure variation.....

 

[Radman]

Fascinating thread guys. 

I am new to this site but have been a pistol collector and shooter since the start of the UK lockdown when I acquired an original 6M which needed new seals but now shoots very well. I have been admiring the LP 53 and finally managed to track one down which will hopefully arrive in the next couple of days.

I am a fan of taking quality vintage gear and sympathetically upgrading so this really interests me particularly as it can easily be reverted to standard.

Once I have found out how it performs as is I will be revisiting this thread for some inspiration!

 

[Luckyshot]

I loved my LP 53 since first laying hands on it 60 years ago. Still shooting great needing nothing more than a new piston seal.

 

[Radman]

Arrived today!

Delighted, came with the original cardboard box and spare rear and foresight elements. No cleaning rod or cocking walnut though.

Serial number puts it around the summer of 1956 I think (016***)

There was lubricant on the breach seal so I put a cleaner through and then a pellet through the chrono which gave 352 ft per sec.

Possible it might still have the original spring set. Felt very nice to shoot.

 

[Steveoo]

Congratulations, despite seemingly small internals (within the grip) these pistols have excellent compression ratio and efficient TP to make good power, trigger lighter than match regulations and excellent rifling….It will destroy (or can be tuned to destroy) most springer pistols.