x2 on the new seal. If the seal is fat/thick (new) then it'll start sealing earlier, hopefully before it punches the hole. I remember "normal" being no leakage or just a slight pfft as did it, certainly nothing significant. The seals last a while but do have a lifespan, and that's shortened if allowed to dry out, are compressed too hard, and no doubt if the wrong lube is used. Crosman parts and shipping are cheap, just go here;
http://tinyurl.com/Crosman-Parts and find your gun, then open the parts pdf. It may be hard to ID the parts on some diagrams b/c they appear to be a xerox copy of a copy of a copy of an old ratty doc. If in doubt just order all the little parts in question since they're no doubt cheap. Most small parts are $1.15, which I believe is also their min $.
To order parts get all the part numbers and quantity of each needed, then email the list to Crosman. Last time I ordered (Jan 2017) it was Sally that did parts orders;
[email protected]. Include your name, shipping address, billing addy if different, and your phone #. Ask her to call you when the order is ready so she can get your credit card info. Phone is apparently the only way they do the billing on parts orders, but emailing all the part #'s and other info is much better for both parties than over the phone. Shipping is $4 per order, very cheap. Sometimes parts are out of stock and back ordered, sometimes they’ll tell you that when you order, sometimes you won’t know until your order shows up missing that part. Said parts will be sent when they arrive, not much point in asking about it because they typically don’t know. I’ve had some show up a few days later, some a few months later, but usually within a week or two.
If in stock they're usually at my door in Calif in 3-5days.
Order spares, any rubber or O-rings etc or anything else you might need since shipping is a fixed $4 per order so might as well take advantage of that.
I make that email a price request first, which she replies, then I can adj qty, delete items etc.
You might also consider the Beeman P17 (~$30-35). It's an outstanding value and similar or better in power to a CO2, but no CO2 to deal with, just one pump. The Crosman 13xx is also pretty cool but ~ 2x the $ and needs multiple pumps (a deal breaker imo).
About that noise: I think it's better to have a quiet gun than a hidden one, which you can do by adding a suppressor. It'll involve some work since the gun(s) did not come with them but it is doable. PCP, Pneu and CO2 are especially loud at the muzzle and have the most to gain, a springer not so much but it does help a lot. So if done right I rekon the neighbors will never hear much to be lookin in the first place. One shot from an unsuppressed CO2 and I'd imagine everyone knows what you're up to.
I suggest the Crosman NP2 suppressor. You can order one for cheap NP214-001 (<$2), which is the suppressor minus the outer tube so you need that or improvise. The NP2 uses a shroud tube NP214-008 (>$6) which can be cut up to make two, maybe three tubes. This may not make sense but I have pix if needed, chevota at hotmail and I can send, just remind me who you are and what you want. You could also wrap it with plastic and tape, just duct tape or whatever depending on your redneck skill level. Lots of peep make airgun suppressors from scratch or misc parts but that NP2 dealie is as if it were for made for us do-it-yourselfers.
Then the suppressor needs to attached to the barrel. The suppressor is plastic with 1/2"-20 female threads so you can do whatever to fit it. You could thread the barrel but most aren't that easy, but you can hog it out bigger to fit your gun, or duct tape it on or whatever.
Fyi, airgun suppressors are illegal per the letter of the law. Obviously they sell them and guns with them and so far nobody is getting jailed as far as I know, but I wouldn't show it to the cops, especially a home brew model. Many peep will insist until blue in the face that they are legal, but obviously they never read the law and you will NOT find any doc from the ATF that says they're legal. So fyi there is a risk. Even if arrested and released w/ charges dropped it would be very unpleasant and possibly very expensive. Many peep site tko22.com which sells similar to what I describe making, but as a kid I bought three different things from diff places/diff times that were illegal, two a felony and one a misdemeanor. Probably more stuff but I clearly remember those. So being available for sale doesn't mean legal.