TargetTalk

Hello guys,
My Walther LP300, which is approximately 15 years old, had experienced a problem that the coil spring in the recoil absorber a few months ago. The coil spring was broken. So, I made a replacement spring by myself. After this event, or coincidentally to this event, first few shots' velocities are slower. E.G., first, second and third shots hit 3in, 1.5in, 1in lower respectively than the center.
What could be a cause of this symptom? I am going to toss this piece in several months. Please note that I am not going to have any gunsmith fix this problem, but I would like to know how come this phenomenon occurs.
The velocity reaches normal level after at least five shots and it is maintained during the competition.

Any suggestions including bizarre speculations would be appreciated.

I don’t have any Walther match air pistols, but I’ll take a shot at it.

Did the LP300 experience the same lower velocity symptom (the first three shots hitting lower) before the recoil absorber spring broke? There could be a possibility that your replacement spring does not have the same amount of coils or tension as the oem spring, causing the gun to have varying erratic velocities.

During the past 15 years, was the pistol frequently used and were the internal seals and springs ever replaced? Sometimes pcp’s need to be shot a few times for the internal seals to stabilize.

My bet is over zealous oiling. The oil acts as a damper on the hammer speed resulting in reduced air release and thus lower velocity. Two or three shots in, the oil is 'wiped' and velocity is stable. Until you take a ten minute break, the oil seeps back, and the problem is there again.

Strip, clean, and reassemble using the correct lube. Some molybdenum grease is usual (black axle grease). Doesn't flow and leaves a lubricating film. Never use any spray grease, and be very sparing with any oil.

kevinweiho,
Thank you very much for the reply.
>Did the LP300 experience the same lower velocity symptom (the first three shots hitting lower) before the recoil ...
No, not at all.

>During the past 15 years, was the pistol frequently used and were the internal seals and springs ever replaced?
Yes, most of o-rings and seals made of chemical materials have been replaced. Exceptions(ones that were not replaced) are a large O-ring in the regulator and a small O-ring on the recoil absorber.
No springs except for the recoil absorber spring in question have been replaced.

> There could be a possibility that your replacement spring does not have ..
I do not think any components made of metals would change their characteristics in a few minutes. Therefore, I am ruling out recoil absorber recoil spring's characteristics.

Best regards,
Masaki

mctrucky,
>My bet is over zealous oiling.
Yes, I did applied a decent amount of oil on the recoil absorber and the striker pin when I replaced the recoil absorber spring. Before I did it, both the recoil absorber and the striker pin had been coated with a very thin layer of oil.
Today, I went shooting. But, the problem did not occur. Usually, I charge the cylinder 250-300bar before leaving home. But I did not do it today. The cylinder contained 150bar of air and I was anticipating that the problem is dealing with cylinder air pressure is too high.
After 80 shots, the air pressure went down to 70bar, So, I replaced the near-end cylinder with another one that was charged almost fully(270bar), yet the problem did not occur.
I think you may be right. It was a warm(75-70F) day today. The over zealous oil had lower viscosity than ever since I replaced the recoil absorber spring and oiled around it. I will disassemble the LP300 in a few days to see how oil has been left on the absorber and the striker pin.

Masaki

guys,
　I tried wiping out and adding lube with sometime, CrMo grease and sometime FWB white grease on the striker pin and the recoil absorber pins, but nothing have changed. This morning, I tried lubing the bore by BC Barricade before leaving the home. The first shot at the range did not have the problem. I can not conclude the cause of the problem was friction in the bore by this single experience. Will try this "lubing the bore" in next week to ascertain.
In Japan, it is said that lead thin layer in the bore protects the bore from rusting and no need to wipe it out. So, I had rarely cleaned the bore of my LP300.