Mark I

[Methuselah]

The guy I posted about at the end of the Mark II #2 thread. Was supposed to be in good condition  ... hisssss (from cap of course).

Didn't fire, leaked but stopped, and I was going to wait because I thought it didn't leak enough to empty the cartridge. So, I figured why wait, if I was right it leaks the rest and time to tear it down, wrong and I can work on the cap again.

It was empty, probably so before I tried to fire it, but either way stuck with fixing the cap.

I had polished the bottom of the piece that threads in to retain the pin's o-ring because it was very rough. Probably shouldn't have. I was thinking it "mashed" the o-ring but now I kinda doubt it. What did happen was it punctured the cartridge just before the cap threads bottomed.

At this point I  don't know it that rough part was in the o-ring well. Doubtful, I just don't think I took off THAT much with 400 grit.

Now I'm considering options. Probably 1st thing I'd try is washer(s) under the retainer and a second o-ring to help mash down the bottom one a bit. I've got some plumbers silicone grease I can use on the o-rings and well.we'll.

[Methuselah]

Pic 2

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Pic 3

From the looks of this, I probably need to polish up where the o-ring sits. Maybe 0000 steel wool?

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Pic 4

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So looking through my bin oder small washers from junk I've cannibalized

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Compression the o-ring a bit

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Move the cartridge away from the needle

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Screw the retainer back.

(Before I do that last step I'll have to dissassemble the end to remove the needle so I can properly grease the o-ring and well it resides in)

Anybody with a better idea feel free to chime in!

[Methuselah]

Looks like I scratched up the o-ring seat, but the finish looks acceptable. Not sure if I can or should try to polish the scratches out or just use the plumber's grease and add those washers to reposition the retainer farther from the needle and "pack" that o-ring.

[Methuselah]

Well, 6 hours in it looked like this
(Continued)

[Methuselah]

Which brought me right back where I started, finding a suitable "tool" to dress that o-ring seat.

I know I had a few end mills and a center finder, but couldn't find them. I didn't want to make a run to Northern Tool or Harbor Freight because they might not have what I want and truth is I'm not sure what I need!

TBT, I'm so torn on how I got to this point in the first place, and couldn't shake the feeling I'd just make things worse.

At least the o-ring well is not elongated or over sized, but it I hit the sides, it could be, and the washers I chose should press it into the bottom.

So, I can always do it over (again), right? The seat area got a good slather of silicone grease,  so did o-ring and pin. Just for s&g's, I greased up the outer o-ring too.

No more premature puncture,  no more hiss.

High power is 454.8 fps with what I believe we're JSB Diablo 14.35 grain. Low was 280 and checked again about 10 shots later 281.4.

Big difference in POI between high and low. I reckon it best to pick one setting and stick to it?

[Methuselah]

See what I mean?

[Methuselah]

They were all pretty good windage wise, but not closer in. I had run out of pellets from a mystery container and think I refilled from a different type.

Edit (Very windy today, so I'll probably pick what pellets I think I started with and try again at 15 yards and low power when it's calmer)

[Methuselah]

Not targets, just some water bottles and empty aerosol cans, switching ammo, yeah  I had filled the little plastic container from the wrong tin ... started nailing everything dead on.

Same issue prevails, big POI shift between low and high.

[Methuselah]

Today the frame felt colder near that end cap and high was 408, low 270.5 fps.

I presume it's leaking slowly.

That mill is still set up, might still have to use it. I think the next step is wait and see how much longer it lasts, and trying an end cap off one of the freshly resealed Mark IIs.

[Methuselah]

Today the frame felt colder near that end cap and high was 408, low 270.5 fps.

I presume it's leaking slowly.

Five days, still got pressure, color me happy, doesn't appear to be leaking after all.

These old Crosman CO2 target pistols are fun