You guys are freaking NUTS..!
First, that's an "aluminum"...bottle.! Seems some need new glasses.
Second, While I don't know what that gun is pressurized to, a gouge like that CANNOT...be "fixed" with some epoxy..!
Mr, mtnGhost -
While it is your face and eyes, and it may take a few more pressurization's, it WILL explode at some point in time, a much shorter time down the road than you'd wish..! I'd be buying a new bottle before I did ANY more shooting. I like my old eyes just where they are.
Mike
P.s. Working in the Aerospace industry for over 35 years and have SEEN bottles explode and why they did...please think long and hard before shooting that gun too many more times without a new bottle being installed.
Unfortunately you happen to be mistaken, it's not an aluminum bottle, both the picture clearly shows the fiber wrap and the OP says it is a CF bottle in his description. Let's not scare monger please. HPA is can be VERY dangerous if misused but if rational standards are followed it is safer than some other sports.
And I have years of experience evaluating CF damage and if it is LESS than a certain amount EPOXY IS THE DOT/FAA/Manufacturer APPROVED METHOD TO REPAIR. Generally if it's less deep than the thickness of your thumbnail it would be salvageable/repairable. There are other factors like the width and length of damage and some other things like bottom profile of the damage that cause stress risers (if there is any crack it's scrap) but on the picture it looks like a scrape, not even a gouge. On the job I measure with something more precise and evaluate with the repair manual before me. But based on the picture it has not gone through the protective layer into the strength layer which would have red tagged the bottle for sure. I describe this so the OP can look closer to make sure it's not V shaped gouge and is a flat bottomed scrape. I took out one of my bottles and compared the width and length of the scrape on his to where it would be on mine. It's also on the neck end where the wrap is thicker/stronger and more damage is allowable - if it were on the cylindrical body 'hoop stress' is more likely from similar damage that long and it might downcheck it.
You say you work in aerospace but so do I at a licensed Repair Station under the Code of Federal Regulations ( 14 CFR ) Part 145 ; When I repair a bottle I have to sign off on it using my FAA A&P license and if an incident EVER occurs I face huge fines or years of prison if I was wrong in my judgement or violated the rules and anyone's hurt or an aircraft is damaged.. not many people know that.
The picture does not appear to show the damage depth to be that much BUT if the OP wanted to be absolutely safe those bottles can be replaced for $100 to $200 unless he sources from the guns OEM who might charge too much... TalonTunes sells a certified bottle if he felt uncomfortable using one of the uncertified Chinese bottles (which NONE of them are DOT certified no matter what lies they say, just CE which is not 'legal' in the US [Note I have several Chinese bottles that I
unofficially hydrotested myself and they passed so I use them on my Texans, any bottle I did not test is questionable for me to use. NO certified hydro shop can test and make legal a Chinese bottle, they have to be MANUFACTURED at a DOT certified facility and no Chinese company has tried to get the certification anyway]).
I have hydroed close to 6000 bottles {about 2500 of those were CF} (you do 30 a day for years and it adds up) and NEVER had a CF fail the hydro after it passed the internal and external visual inspection and/or repair I did! Lots of steel, stainless steel hermetic fire extinguisher and aluminum bottles fail, it's actually scary how many. I've filled a dumpster with those!
I could more comfortably suggest he locate a hydro facility with a familiarity with CF bottles (just because they hydro doesn't mean they know CF) and ask them nicely to do a visual and OK it. But if he could not get it done for free then it might cost more than a new bottle if they charged.
P.S. / FYI - Note that it's a gun bottle and they don't get tested like the bigger bottles because they aren't usually taken to commercial fill stations (as long as you use a bottle privately the DOT does not apply! Transported, used or filled
commercially DOT rules) BUT if it were to be judged but the same standards then the repair HAS TO BE TRANSPARENT and if you used a marker it would automatically fail the bottle the next time because the inspector could not see the previous damage because it was 'covered up'. Also for the tube guns or the section of tube on a bottle gun, anything under 2" is not DOT regulated so they don't have a lifetime or need to be tested or documented.
Now let the OP decide what he wants to do