First pcp "locked up"

[wayno63]

Hi all, picked up a btocock contour last week for backyard ratting/pinking, gun was charged when I got it so bought an air bottle kit as I had shot a number of pellets and noticed a slow drop in accuracy so used the bottle to top up. Pressure gauge reads just over the 200 max on the gauge but not enough power for the pellet to even leave the barrel, had to manually push it back out. Read somewhere about it being "locked up" but nothing on how to resolve the problem. Any ideas?

wawayne

 

[JohnL57]

Welcome, Wayne!
It sounds as if the gun is overcharged and the valve is locked due to too much cylinder pressure. You need to degas the gun somehow. Did it come with a degassing tool? The Benjamin Marauders us a threaded degassing tool that opens the valve manually by threading inward. I would call the folks at Airguns of Arizona for advice on how to degas.
If there is no such tool for that gun some disassembly may be necessary to degas. Never disassemble any pressurized parts while the gun is charged! Make sure you understand what you're doing before you attempt any disassembly.
A word to the wise-the gauges on most guns are notoriously inaccurate. It's much wiser to trust the gauge on your tank fill setup.
Good luck and keep us posted!
John
PS-once you get back to shooting you'll get the most out of your gun by using a chronograph to figure out the best fill pressure and the number of good shots per fill. I borrowed one for setting up my guns and eventually caved in and got my own.

 

[sirk]

Hi, next time you fill it to 150bar only and test fps. add 10bar more test again too find when the output plateau ends.

just keep it firing without pellet, at least you burn in/loosen up the whole firing mechanism.

that is an unregulated gun, it will have max power at medium fill.
then both sides eighter too low pressure or too high pressure, power will be low.

 

[wayno63]

thanks for the reply, the contour does not come with a degassing tool, so i searched the web and found that dry firing will slowly bring the pressure down sore thumb and forefinger later the pressure is just under the 200 mark, problem now is although the pellet leaves the barrel it drops short of the target i set up previously by about a foot or so. my initial thought was that the breech seal had blown out but checked and its still in place. without a chronograph i cannot tell the power out put but i could probably throw a pellet faster.

 

[sirk]

i dont think they like more than 170bar in the cylinder.
next time you do it the other way round. fill in 80bar, shoot it, add 10bar, 10again etc. keep filling up until power drops off.

otherwise you will waste too much air. and lot of work/time

 

[wayno63]

Dry fired it down to 150 and is a lot better, will try the slow increase next time and will also enquire about borrowing a chronograph. 

 

[sirk]

good stuff.