Finally let me down….

[StockMike]

After somewhere in the ballpark of 20 years playing pretty much exclusively with a phantom (couple breaks here and there from the game in that time span), I finally had a Phantom break down on me today.

I had a rear air valve using 12 grams and it would only shoot a single shot. There was no leaks. I’d dump the 12 gram, and it was still full. Put a new one in and the same thing would happen, only one shot and it wouldn’t cock after that until a brand new 12 gram would be put in.

After 2 games fighting with it, I sat down and swapped the valve for a VSC (thinking maybe liquid co2 from the rear valve was getting into the valve body and causing issues with the cup seal. I swapped out the cup seal for a brand new one, swapped the valve spring, and swapped the main spring for a red one (because the velocity I was getting from that one shot was only maxing out around 245 fps).

After all thar, it was still shooting extremely inconsistently. One or two decent shots in a row, then a shot would barrel get out the barrel. At the chrono, it was wildly jumping around between 275 and 150. It was a mildy hot day at around 82 degrees. What else could be causing this issue besides a cup seal or one of the springs?! I didn’t think there was anything else even in there that could be the issue!

Any thoughts?

[Jonnydread]

I’ll wager there are multiple factors at work, but I bet one of your problems is the co2 heating up and expanding and causes pressure spikes that are prematurely closing the valve, thus lower FPS.

[StockMike]

If the co2 were expanding too much because of heat, wouldn’t the valve being effectively stuck shut still allow me to cock the gun and have the hammer and bolt still be able to be latched?

[Jonnydread]

StockMike I am specifically referring to the second issue once you reconfigured. Not sure about the first one

[StockMike]

Ohhh gotcha. Yes that certainly does make sense for the velocity issue, once I was getting the gun firing.

[Pyrate Jim]

Only time I had a problem like that, it was because the cup seal had snapped the threads on the power tube inside the valve and was "floating" loose.

[StockMike]

My thought was the cup seal as well, and I tore the valve down between games and unscrewed the cup to replace the seal. So nothing in there was stripped or bent or broken or out-of-place looking.

[flyweightnate]

Check for a burr in your frame hanging on the sear. I've only seen it once on a really old (four digit SN) frame, but the pump arm had mashed up the slot around the roll pin so much the hammer would drag most of the time.

[StockMike]

I will take the trigger group off either tonight or tomorrow and see if there is any damage there.

[StockMike]

[Chuck E Ducky]

When was that cup seal purchased?

EV put out cup seals that can’t handle CO2 (to soft) and they realized it late, then made them (HPA only) cup seals. If you happened to get one of those it’s will cause the issues you described. What happens is the cup seal sticks causing all kinds of inconsistencies.

Try your old cup seal we know is good and flip it over the issue should go away for the next 10+ years.

[StockMike]

If my memory serves, which could go either way really, I purchased this pack of cup seals when I ordered a spring feed from EV. It was within a week or two of when they first started selling them. Was that in the time frame of the faulty cup seals?

[Chuck E Ducky]

Yup it’s likely just your cup seal.

[JeeperCreeper]

That valve pin, it's hard to see in the picture, but it looks rough? If you put the valve back together, does the pin move freely, or feel scratchy like it's hanging up? I've seen rough / bent valve pins in Sheridans cause serious inconsistentcy issues before. It's worth checking.

[StockMike]

The valve stem is definitely sort of rough, but has been since I took ownership of this particular Phantom. It looks worse in that pic than it really is. It’s almost like that whole section of the stem has uniform tooling marks. They aren’t on the other side of the flange though, just the side that the hammer and bolt interact with.

[Grendel]

It did not let you down it has served you well for a long time. Any tool needs some level of maintenance over time

[StockMike]

I didn’t mean to make it sound like this Phantom is neglected! Far from it! After every time it sees the field I tear it down and clean it. I’ve replaced the o rings and cup seals and puncture pin seals several times. I didn’t see any parts that were an obvious culprit when opening it up at the field over the weekend when troubles arose however. Figured I would enlist the help of the many MCBers who are far smarter than me though!

[Grendel]

No problem just poking some fun.

[NONOBLITUS]

One little thing to check is the nylon set screw that holds the velocity screw in. I had one that stripped and caused massive velocity swings. Not saying that’s it but worth a check for the Chrono issues

[StockMike]

I did check that at the field, but that set screw is holding the TPC pretty firmly.

[Chuck E Ducky]

Large velocity swings can also come from adjusting the TPC past its adjustment range this lets the TPC flop around. I don’t think this is the issue since you haven’t changed springs.

[Chuck E Ducky]

I’m willing to bet it’s just the faulty cup seal issue EV had right around the time you ordered them.

[StockMike]

That’s too bad. I still have 2-3 from that batch I ordered back then. I’ll order some new ones and retire these NOS ones. Thanks for the help! I would have never guessed there was a bad run of seals out there.

[Araphel]

Well, I've got some good news about new cup seals.....

[Chuck E Ducky]

You get them figured out?

[Araphel]

I think so. I want to test them out a bit more.

[SignOfZeta]

Did EV ever try a “recall” of sorts to address this? Like just emailing everyone who bought a seal from a certain time frame and telling them what the issue is, even if they don’t actually replace the things?

[Prometheus]

I too had a similar issue. By the look of the cup seal that is a big part of your problem. As it doesn’t like CO2.