???? Walther LP53

[Steveoo]

The design can be astonishingly accurate. Often criticised for upward recoil, once learnt can be highly repeatable …meaning its a singular upawrd thump which is not complex. Rifling and trigger are match quality …..but my gun at 520 fps gets the pellet out the gun before the recoil.

 

[Roboslug]

Thanks Steveoo. I'll definitely be reaching out to you as I just bought a used Predom. This will be my first springer of any kind.

 

[Luckyshot]

Steevoo, good to see your passion for the LP53. That's very impressive FPS for any springer air pistol but especially the LP53. Love mine though it does not come close to that number. More like 375 to 390 w/7.4gr pellets. Still using the stock springs that were in it in 1961. I only replaced the breach and piston seals. Though I did not have a chrony back then, but my sense is that any power drop off has been miniscule.



Regards,

 

[Steveoo]

Heres the thing. The LP53/Predom design has power wrapped up in it, but in OEM spec it cannot realise it.

Despite the seemingly small internals contained in the grip, the piston is very short, meaning the stroke is quite reasonable 45-48mm but also quite big in diameter at 23mm. The HW45 is 22mm and the Webley pistols 19mm in comparison, also, the LP53 has a transfer port directly in line with the barrel and quite short which gives maximum efficiency, unlike the Webley pistols turning through 90 degrees.

The problem with the design is the 2 mainsprings rob power from each other and the piston head too thick. Once sorted the velocity will increase 100 fps and outshoot any Webley pistol.

You can get upto 440 fps stock ….check the condition of your seal and look for any binding of the mainsprings which occurs if they are not true.

 

[Luckyshot]

I wonder if removing the smaller spring would increase performance. Probably need a larger diameter spring retainer though. Actually, if the fps remained about the same it would be a win from the perspective of input vs output as long as firing action was not adversely effected.

 

[Steveoo]

I did try just the large spring on its own during my early experiments 20 years ago….losing no velocity, but gained smoothness by using a 12mm guide, incorporating an 8.2mm hole to pass over the OEM 8mm guide to keep the spring straight. Its not the best spring, having little gap between coils,,presumably so it did not bind too much on the inner spring. However, a Cometa 50 or HW30 mainspring is much better.

For the unskilled without access to a lathe, you could mod the gun reasonably well by purchasing a HW30 spring kit like the Vmach kit shown. The HW30 spring is what i used with my own modded gun …fits perfectly. You need to trim it to 18 coils and then cutting 1/2 inch off the length of the guide rod should not be too difficult with a hacksaw and file.

 

[Luckyshot]

I did try just the large spring on its own during my early experiments 20 years ago….losing no velocity, but gained smoothness by using a 12mm guide, incorporating an 8.2mm hole to pass over the OEM 8mm guide to keep the spring straight. Its not the best spring, having little gap between coils,,presumably so it did not bind too much on the inner spring. However, a Cometa 50 or HW30 mainspring is much better.

For the unskilled without access to a lathe, you could mod the gun reasonably well by purchasing a HW30 spring kit like the Vmach kit shown. The HW30 spring is what i used with my own modded gun …fits perfectly. You need to trim it to 18 coils and then cutting 1/2 inch off the length of the guide rod should not be too difficult with a hacksaw and file.View attachment 122147

I finally got around to experimenting with my 53. I did try the single spring route and had results opposite of your's. The single spring (with homemade guide) produced only 290fps. When using both springs, it was putting out 378fps. Previous to this experiment I had installed the T. Robb piston head, which I found somewhat harsh. Judging from the photos of your set-up, the HW30 spring appears to be quite heavy. So I had no chance of getting close to the 500fps you are enjoying with your modified 53. I was more interested in smoothing out the 53's manners than higher fps. However, I appreciated your comments and expertise.

 

[Steveoo]

Sounds like the set up of your guide is somehow flawed as no one else ….ever …has had one shooting so low, and in stark reverse order of going back to the old double spring…
Put a pic up of your power pod and ill see if i can spot the issues for you.

 

[Luckyshot]

Sounds like the set up of your guide is somehow flawed as no one else ….ever …has had one shooting so low, and in stark reverse order of going back to the old double spring…
Put a pic up of your power pod and ill see if i can spot the issues for you.

In the 2 spring mode, my LP53 seemed to compare favorably with other reports of fps I came across. Here's the pic of the single spring/ guide set-up I tried out. I didn't remove the piston with the T.Robb head due to it being a PITA to remove.

 

[Steveoo]

I have instantly recognised your issue.
That looks a very close coil mainspring….Check the gap between the coils on the spring above it.
Also it looks like the guide is a piece or rolled still with a big gap where it joins. Like a super size roll pin.
That groove will play havoc with efficient spring expansion..

 

[Luckyshot]

I have instantly recognised your issue.
That looks a very close coil mainspring….Check the gap between the coils on the spring above it.
Also it looks like the guide is a piece or rolled still with a big gap where it joins. Like a super size roll pin.
That groove will play havoc with efficient spring expansion..

By "close coil" do you mean a "tired" mainspring? The guide fits snug but moves freely when the spring is compressed.

 

[Steveoo]

The design of the spring (can be brand new) is with coils which are set close together, probably meaning a light duty spring like fitted to a gamo pistol, Umarex etc…
You might also try polishing that guide for a more slide fit…

 

[Modski66]

Following this with great interest; I have recently purchased a Predom Lucznik that is running at around 375fps, but has a very rough trigger and a nasty torque-twitch to the left when firing.
I have an HW30 spring on the way, some Delrin in stock, and my lathe ready to go.
Still considering making a new piston head with an o-ring, but I will see what the original seal is like before deciding.

 

[Luckyshot]

The design of the spring (can be brand new) is with coils which are set close together, probably meaning a light duty spring like fitted to a gamo pistol, Umarex etc…
You might also try polishing that guide for a more slide fit…

This was the original spring. My dad purchased the gun new in 1961.

 

[Steveoo]

Aghhh….of course. I do not know why i had not spotted it earlier. I noticed an unusual, close coil spring, but of course its the OEM original. It was designed that way so that the inner spring could not get in between the coils too much when compressing it. I have never known one used on its own because it would never be powerful enough…
It would be hopeless as a single spring….that is your problem sorted.

In addition, with both springs, a decent running LP53 should hit around 420 fps.
So this suggests your Robb seal is not as good as it could be..

Where on earth did you find that super size roll pin for the guide….Ive never encountered such a thing.

 

[jkingrph]

I am still awaiting shipment on a couple of parts from the UK, a spring kit and guides from Protek and a piston head / seal from TR Robb and seem to be getting the run around on shipment. Robb wanted an extra 10 lb fee to provide tracking info, and Protek said should get new kits to ship week of Feb 28, but now says they are still waiting. In the meantime mine still has a stuck piston, in down or cocked, I suppose, position, with spring removed. Even if I pull trigger cannot move piston up.

 

[Steveoo]

Do not worry…Your Trigger bar sear has simply dropped into the sear slot which happens if you attempt to remove the piston with the Trigger bar sear in place….as its spring loaded.
Tap out the pin for the Trigger bar sear (red arrow) and then easily pull out your piston.
Keep the small spring behind the Trigger bar sear (Blue Arrow) safe in a plastic box until ready to re-fit as its unobtanium.

 

[Modski66]

@Steveoo - Do you know if barrel of the Predom can be easily removed from the the pivot casting?

 

[jkingrph]

Like I said, I am awaiting on the spring kit from Protek, and the synthetic piston head. If they do not show up in the next couple of weeks I have located a company that says they can work on it. With everything hidden and no experience I am reluctant to try anything.. It seems as though the piston is frozen, it will not in the current state of affairs move either up or down, apparently somewhat down as the mainspring assembly simply will not go back in.

 

[Luckyshot]

Aghhh….of course. I do not know why i had not spotted it earlier. I noticed an unusual, close coil spring, but of course its the OEM original. It was designed that way so that the inner spring could not get in between the coils too much when compressing it. I have never known one used on its own because it would never be powerful enough…
It would be hopeless as a single spring….that is your problem sorted.

In addition, with both springs, a decent running LP53 should hit around 420 fps.
So this suggests your Robb seal is not as good as it could be..

Where on earth did you find that super size roll pin for the guide….Ive never encountered such a thing.

I'll solve the mystery for you. Not a roll pin. The spring guide was fabricated from a Daisy bb gun spring guide. I cut it down to the desired size. The slot allowed me to pry it open to the desired diameter. I inserted a spacer into the guide to fit snuggly on the screw-on cap.