New to this - how long should a CO2 tank last when unused?

[cnwinger]

I have a Sig Sauer MCX-177 MCX that I very rarely use to shoot at coyotes that jump over my fence and get too close, just to scare them away. It's probably overkill but I wanted something semi-auto because firing several rapid shots at the ground in front of them scares them away a lot easier.

This works well with a fairly new 90g CO2 tank. However, when I let it sit for a few weeks and then come back to use it when needed, the CO2 seems to be empty and I can only get off a single shot at a time by using the pull-lever. This has happened several times. Is this expected behavior with letting a CO2 canister sit for weeks? If not, is there some sort of adapter, etc. that I need to prevent the canister from slow-leaking over time?

Thanks.

 

[nervoustrig]

If the seals are good, it should hold CO2 for many months. I frequently leave my CO2 airguns charged over the winter and they still have pressure in the late spring or early summer when I bring them back out. A slow leak is but a minor annoyance when you’re dealing with inexpensive 12g cartridges but the 90g tanks are expensive so I’m sure you’ll want to deal with it. Replacing O-rings and seals are certainly within the realm of the do-it-yourselfer or you can see about sending it off for repair. 

It’s generally a good idea to go ahead and replace all the O-rings since they are relatively inexpensive compared to the disassembly/reassembly effort. Plus the fact that many OEM O-rings are poor quality. Polyurethane is the best choice followed by the more commonly available Buna-N. 70 durometer (hardness) is generally best for CO2.

Deburr any holes the O-rings must pass by during reassembly, and use silicone grease to ease assembly and reduce the risk of damaging the new O-rings.

Another spot it can leak is from the poppet (valve stem). That part isn’t an off-the-shelf item…you’d need to get one from the manufacturer or search online. It’s usually a long lasting part so I wouldn’t say you need to have a replacement at the ready, but be aware that it’s a part to check. Sometimes a piece of debris gets squished into the poppet where it meets the valve seat and causes it to leak slowly, or the surface gets scratched by a sliver of metal left over from manufacturing.

 

[cnwinger]

If the seals are good, it should hold CO2 for many months. I frequently leave my CO2 airguns charged over the winter and they still have pressure in the late spring or early summer when I bring them back out. A slow leak is but a minor annoyance when you’re dealing with inexpensive 12g cartridges but the 90g tanks are expensive so I’m sure you’ll want to deal with it. Replacing O-rings and seals are certainly within the realm of the do-it-yourselfer or you can see about sending it off for repair. 

It’s generally a good idea to go ahead and replace all the O-rings since they are relatively inexpensive compared to the disassembly/reassembly effort. Plus the fact that many OEM O-rings are poor quality. Polyurethane is the best choice followed by the more commonly available Buna-N. 70 durometer (hardness) is generally best for CO2.

Deburr any holes the O-rings must pass by during reassembly, and use silicone grease to ease assembly and reduce the risk of damaging the new O-rings.

Another spot it can leak is from the poppet (valve stem). That part isn’t an off-the-shelf item…you’d need to get one from the manufacturer or search online. It’s usually a long lasting part so I wouldn’t say you need to have a replacement at the ready, but be aware that it’s a part to check. Sometimes a piece of debris gets squished into the poppet where it meets the valve seat and causes it to leak slowly, or the surface gets scratched by a sliver of metal left over from manufacturing.

Thanks for all the great info. Sounds like I should start by replacing the CO2 O-ring. ow can I determine the specific size to purchase for the Sig Sauer MCX-177 MCX ?

 

[d3vnull]

I'm going to go out on a limb here and guess all CO2 90g o-rings are the same size:

https://www.grainger.com/product/FABORY-Round-112-Very-Hard-Viton-2KAL6

If you don't have a local shop to source one to test then PM me your address and I'll drop a few in the mail for you.

 

[shoot44]

del

 

[Odoyle]

If you don't do much shooting just to scare away yotes you don't even need to waste money on 88 or 90 gram co2s. Super expensive! Even if you got a leak I would personally rather have a 12 gram co2 leak over time it's way cheaper anyway...

https://h5-aliexpress-com.cdn.ampproject.org/v/s/h5.aliexpress.com/item/33004320390.html?amp_js_v=a6&amp_gsa=1&usqp=mq331AQFKAGwASA%3D#aoh=16033108564696&amp_ct=1603310967922&referrer=https%3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s

Hmmm Aliexpress competitor? Cheaper here...

https://m.banggood.com/88g-to-12g-CO2-Capsule-Cartridge-Converter-Adapter-Suit-for-Air-Rifles-Guns-p-1589975.html?utm_source=googleshopping&utm_source=googleshopping&utm_medium=cpc_organic&utm_medium=cpc_bgs&gmcCountry=US&utm_content=minha&utm_content=frank&utm_campaign=minha-us-mb&utm_campaign=frank-ssc-us-all-newcustom-ncv90-0623&currency=USD&cur_warehouse=CN&createTmp=1&ID=6157220&ad_id=443948744865&gclid=Cj0KCQjwuL_8BRCXARIsAGiC51DlDfjN30Sogjh0ViCkDyB9PTAMJo1WPFnOYF8aOstlwsNhI3w8Ym0aAuFBEALw_wcB

WATCH THE VIDEO for this one!

https://h5.aliexpress.com/item/4000028761424.html?spm=a2g0n.seo-amp-detail.moreToLove.4000028761424

Still shipped from China if you want to pay more $$$ here... Compare Aliexpress shipping vs this one with free shipping first...

https://www.ebay.com/c/938419566

OR run TWO 12 gram co2 here see if the 15% + 15% discount code still works...

Double your pleasure? Double your fun? Enjoy more shooting with Umarexusa dot com?

https://www.umarexusa.com/2x12-gram-co2-adapter-for-air-rifles

Sure cheaper than the original $100 2x12gram Umarex adapters sold years ago!!!

Oh bummer...it's out of stock... Sign up to get notified when available but I would suggest getting one or 2 or 3 (different types) of the single ones in the mean time it's cheap enough.

Eventually Pay for themselves by not needing to waste money on 88 and 90 gram co2...

 

[Odoyle]

OH BTW I'M MR FRUGAL...

FEEL FREE TO PAY MORE IF YOU ARE RICH...

 

[Mike_Lenardon]

Mike, dont forget to put a drop of pellet gun oil (trans fluid) on the end of the co2 cartridge. I have two co2 guns that I shoot inside during the winter. They hold co2 forever.

 

[cnwinger]

Ok, this looks like it's not an issue with CO2 leaking after all. I went to remove the CO2 tank after the gun wasn't firing, and it still had pressure left in it...so not a leak issue after all.

I installed a new CO2 tank and a new clip, and the gun still fires only a single shot, then nothing. The rear of the gun is getting cold from the CO2, so that appears to be feeding correctly...but the semi-auto just isn't working anymore. Is there something simple I am missing here as a beginner, before I contact Sig Sauer?