Canadian Airgun Forum

Hi....

I have a Winchester 500XS that i bought from Walmart just over 12 months ago.
Ok... i know its a cheap crap rifle, but i have had great fun with it for the past 12 months.... Until last weekend.

It started failing to fire and leaving the pellet in the barrel. I havent changed pellets or anything like that... It just started failing to fire.

When it does fire, it no way reaches my targets that are only 40ft away!! And its going so slow you can see it!!!

I stripped the whole thing down tonight, cleaned it and rebuilt it (first time ever and completed in an hour) and it still doesnt work correctly.

Looking at the plunger seal (if thats what its called) it looks ok, but a bit harder than what i was expecting.

Can i buy a replacement seal?? If so, where from??

I am open to any ideas to fix this.

Thanks for any replies.

hi

unless your fired it 50 000 times, or put some kind of corrosive lubricant down your chamber, I doubt seals are the issue, not the first time I hear of an issue like this with a Winchester, in fact I had the exact same issue with my Winchester 500x, I believe mrmarvin was selling one that had that problem as well, and this only after 250 pellets from new, I was only able to solve it by taking it apart and adjusting the piston till I could move it freely back and forth with my finger(adjusted using a dremel as I added material to the piston), also, the right amount of moly was critical, shoots strongly every time now, if you didn't modify the piston, then its probably a lube issue, the breach seal could be an issue, but if it protrudes a little bit, then you would be fine

if you do take it part again and decide to lube it, use moly sparingly, otherwise, it will spit lube out in the barrel

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Can empty space really exist ?

Thanks for the advice Robipaul.

I stripped it again and carefully sanded the side of the piston with a dremel as you suggested.
Mine was very tight before needing grips yo move it back and forth.
Now there is some slight friction but no where near as tight and she fires brilliantly!!

Had around 50 shots through it to line up the sights again and all is good.

Thank you again.

Ok... Spoke too soon!!!!

Further firing to tune in the sights again and its doing the same thing!!!!

Bugger!!!

How loose can the piston be and still fire properly??
Right now with just the piston in the barrel, if i shake it slightly the piston moves.
Should it be looser so it moves just on tilting the barrel??

like i said, it should be loose enough to move with fingers back and forth without much effort(almost freely but shouldn't move by itself), also, you need to lube the piston contact surface with molly or similar substance(very lightly), this includes the skirt behind the piston, just make sure you go very light on the lube, a little dab on a brush should be enough for the entire skirt, as stated, you don't want it spitting out in the barrel

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Can empty space really exist ?

oh, if you have it apart, i would suggest two things that increased the velocity, but not over 500 fps;

1- add a washer to the back spring guide, should fit snugly

2- take the piston off the piston assembly, and add a dime(or whatever fits well to stop the wobble) on the bottom of the piston and put it back on the assembly, i can so see that wobbly piston being part of the issue for the jamming !

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Can empty space really exist ?