LP10 Issue

[ihasagun]

My BFs LP10 has developed a problem with being underpowered, regardless of which cylinder, and then starts working properly again after a few cylinder changes. The underpower part is so severe the pellet does not even exit the barrel. Any ideas?

[Gwhite]

If it happened all the time, I'd suspect a problem with the firing valve. Because it's affected by cylinder changes, it sounds like a problem with the internal pressure regulator. Repairing that is probably best left to the pros (like Pilkguns).

[ihasagun]

Is there any chance it could just need a new o-ring? His o-ring has not been serviced for a couple of years at least. It is dry and hard. I ordered some of the special grease for it, but I d t have a replacement o-ring.

[jliston48]

I had an identical problem with my LP10, although changing cylinders had no effect.
In a competition match, the first 1 or 2 sighting shots went under the target with a sound/feel of an under-powered shot then the next 2 or 3 shots climbed into the 10-ring then stayed there (I made it shoot many 9's and a few 8's but that was me. At least I could quite satisfactorily call most of the shots). The problem seemed to be worse on cold days - less than about 16degC (60degF).
I was always afraid that the problem would not self-correct but it always did for about 10 matches.
My solution was to remove the regulator unit and thoroughly clean it. I disassembled it and although there was no obvious debris in the unit, soaked the parts in solvent, dried them then replaced them. CAUTION: there are 8 convex washers in the unit. Reassemble them just as they were. HINT: as you remove them from the regulator, slide them onto a pencil or similar to preserve the order.
It has worked faultlessly for 3 matches so far.
I refer to this as a "carburettor" problem. In a previous life as a motor mechanic, the first "fix" for a carburettor problem was to remove it, strip it, clean it, fit new gaskets and replace it. This fixed 90% of the problems.

[greentangerine]

Nothing constructive but having read this and your other recent posts it looks like you bought a lemon.

[jliston48]

No! Not a lemon - just a minor problem. It worked well for 5 years before it had the problem (that I let go on for too long hoping it would self correct).
I knew the problem was the regulator because I swapped it with my wife's regulator and her pistol then had the problem and mine didn't.
Being the gentleman that I am, I did swap it back!
Seems to be working well again - so far.

[ihasagun]

That regulator service sounds like more than I care to take on personally. My BF is a mechanical genius, but he has no experience in this arena yet. So I will send it to Pulkguns on good advice. Thanks.

[ihasagun]

Sent it in to pilkguns and got a complete rebuild. Now it works great.

[jliston48]

Sent it in to pilkguns and got a complete rebuild. Now it works great.

Did they say what the problem was?

[ihasagun]

They replaced the regulator and all seals. And there was a burr on the striker that was slowing it down.

[ihasagun]

On second glance, the firing valve was replaced, not the regulator.