Crosman 1077 C02 Weak, low shots per cartridge

[Jerry_NJ]

My 1077 is at least 5 years old, perhaps 30 CO2 cartridges or approximately 1,000 shots.  I took the gun out yesterday and found it ran out of pressure after two mags or 24 shots.  I loaded la second cartridge and gave the gun about 10 minutes rest in full sun at85 air temp.  The gun felt hot to my hand, yet low power on the next magazine of 12 shots.  I opened the chamber and gas rushed out.  I think the gun may be malfunctioning in transferring pressure into firing chamber.  I do not have a velocity measurement but think the first 12 shots had near normal velocity based on impact on beer can full of water,  Any suggestions?

[Ol'DeadEye]

Do you put a drop of pellgun oil on the tip of a new co2 cartridge when you replace it?
Valve might be sticking...
See Section 7 of the owners manual...

[Jerry_NJ]

I used 3 in 1 oil, not pellgunoil.  Suppose that matters?

[Rick67]

I used 3 in 1 oil, not pellgunoil.  Suppose that matters?

That will ruin seals and o-rings.

Use non-detergent SAE 30 engine oil---O Reilly or any auto stores.

Should last you a hundred lifetimes, lol!

[Jerry_NJ]

Thanks, hard to believe the oil type is so important, but
Used pellgun oil today and got reasonable performance for 4 magazines or 48 shots.  I also used a screw driver to be sure CO2 chamber was tightly sealed.  I find it hard to get that tight using just fingers.  That may have been a major contributor.   I will take a few shots again tomorrow,  Fun gun for plinking hope it'll last just one lifetime for an already old man.

[farrlarr]

CO2 guns are designed to seal the reservoir with only finger pressure, even though, for apparently unknown reasons, the cap comes with a slot that one might suppose should/could be used for a screwdriver to tighten the cap.  Cranking down on the cap is not need to seal the reservoir and set up the cartridge for piercing.  Using a screwdriver to tighten the cap beyond finger tight can lead to squashing of the cap seal, contributing to cartridge sticking in the gun or other problems that have been discussed in many threads here (Use the Search button above to look for those threads.).

[Model25]

Pellgun oil is nothing more than 30wt, high detergent, fleet truck oil.
 3 in 1 hurt Buna-n seals? Not a chance.
Absolutely no offence intended, but these “special” oil myths go on and on. A simple search for the MSDS safety sheets on these products will reveal what is behind the curtain. Don't take my word on it, look it up for yourself.
I am personally fond of ATF. About 20 wt and most have a seal conditioner as part of the additive package.  I offer up my 60ish year old Crosman 114 as an example. It was raised on 3 in 1 for its first 30 or so years and then I switched it to ATF after it was handed down to my wife. And yes, it has always been stored charged.
Instead of the stress over oil, it’s just not that special, I would be wondering about the age of the Hoppe's 9 that Bob used in his soak test. Hoppe's did at one time, but I doubt still does, contain Benzene. As I recall,Buna-n is not compatible with Benzene.
Have fun with it, Mike

[Jerry_NJ]

Thanks for the thoughts, but there doesn't seem to be a consensus, or I missed it.  For my part, I have continued to shoot my 1077, and converted to Pellgunoil.  The outcome is I can now get up to for magazines, 48 shots with reasonable power (no not have velocity gauge).  My assumptions is the gun had "dried" out due to lack of use over the last year and the regular use with oil on the CO2 cylinder and the threads has resulted in some rejuvenation of seals.  To get for magazines I allow the gun to warm for 5 minutes after each 12 shots in an ambient of low 70s degree F.  Seem reasonable?   I have stopped tightening the CO2 cap beyond finger tight and I use oil on each set of shots.