Complete newbie looking to get setup to shoot some squirrels

I whitetail bow hunt and I have a crazy amount of squirrels hanging around this year and I thought I would use deer rifle season to take a few of them out. I currently have a Gamo Hornet .177 with about 25 shots on it and I was hoping to outfit it a little better to use. I am thinking that I want a better scope and possibly switch to some different ammo. Right now I have Crosman Destroyer and the junk scope that came with the Hornet. My questions would be what scope and what ammo to use to hopefully kill some squirrels out to about 25 yards or so.
 
I would stick with that scope so long as it's doable out to 30-40yds (most are). I only say this because springers EAT scopes. You would t want to outfit a 100+ dollar scope just to tear it up in fewer shots than you have on it now... 

Aside from pellets, whatever shoots and groups good should get you by. I suppose you could try a heavier weight pellet for a bit more knockdown power 
 
I looked at the stats for that rifle. Looks like it has plenty of punch. But those 1000 fps springers seem to me to loose accuracy with such fast pellets. No matter how much power you have behind it, a 177 needs to be precise for a clean kill. Something fun to do for me was going someplace with a good list of pellets sorted by weights and price (I like Pyramid Air) and just get four or five different pellet types. Try some heavy pellets, some polymags, etc. Find the most common distance and work at your artillery hold until you get 5 shot groups on a dime size. If you can do this, squirrels don't stand a chance. If you can't get it to group you might have to look at a different tool. A better scope might help but you don't want to put a 200 dollar scope on a cheap gun just to find out that your gamo won't group. On paper, even with a cheap scope (unless it is broken) you should be able to see what your rifle groups like. If you get tight groups on paper, then you know that a scope upgrade will help. I went through a lot of cheap springers, cheap scopes, and ammo before I just broke down and got a quality, dedicated, squirrel getter (.25 pcp). But even the cheap ones can hit the mark if you find the right pellet....sometimes.
 
thekevin,
The crack is from the speed. Breaking the sound barrier and you will get a little crack. I had a superstreak that pushed pellets and had that crack. Pretty wicked but also, on an 8 grain pellet totally screwed accuracy because when the pellet comes back to subsonic it destabilized and wobbled (at least that is the theory). Ted had a few good videos out there about hyper fast pellets. That is why sometimes heavy pellets in those powerful rifles shoot better because they keep the velocity down around 800-900 fps. PCP's can be LOUD because not only do some push pellets very fast, but also the large amount of air pushing the pellets can be loud enough to make your ears ring. The nice thing about PCP's though is that they are usually more expensive, which means that they put more engineering into them. Much like the Gamo Whisper but more so. The super quiet guns strip the excess air through a barrel shroud and air stripper the same way a silencer strips muzzle blast from a fire arm. You will still get a crack from sonic rounds but most people who shoot for accuracy with a 177, 22, or .25 try to tune their pcps to shoot subsonic so their is no destabilization.
Also, 
Be careful with using brushes on a pellet gun. Pellet guns are not burning powder. They do not have copper plated pellets. They are different than firearms. I think there are good videos out there about cleaning air rifles. A brass brush can really mess up the delicate rubber seals on an air rifle. Personally, I clean my rifle only when I see noticeable accuracy loss (every couple hundred rounds) and do with with a fishing line and some dry patches.
All of this stuff is not really that complicated, but if you are like me you go into air guns assuming they are like mini firearms. They are different and a lot of the fundamentals do not cross over. I even got a .25 bore snake for my first pcp rifle. Glad I stumbled upon a video explaining how to clean an air rifle before I used it.
 
thekevin: .177 is easily cleaned by pushing (a lot) of Q-Tips through the barrel. Also, you can use a solvent, just make sure you get it all out, and don't put it anywhere near the chamber. Simple Green usually works well also. Take your time, most springers (in my experience) have filthy barrels out of the box. 
If your gun is especially noisy, it is likely due to "deiseling." Basically, there is excess lube inside your new gun (I think you said it had 25 or so shots through it?) being compressed inside the chamber every time you shoot. The compressed lube then detonates, creating the loud crack, or at least accelerating your pellets to a speed that breaks the sound barrier. I have two unmoderated NP springers that are capable of slinging H&N Terminators at 1000 FPS, as shown by the chrony. These guns do not "crack," as the pellets are not breaking the sound barrier (1000 FPS and under really "shouldn't" crack). After you clean it, shoot your gun...a lot...and eventually it will settle down as it burns off that excess lube. If after you've "broken-in" your gun it is still loud, start shooting heavier pellets to see if that slows/quiets it down. My .177 really likes JSB 10.34gr domes, and Crosman Ultra Magnum 10.5gr (when I can get a good tin of those, I mean). Best of luck!
 
I shot the JSB Exact Beast Diablo 16.2gr pellets from my Umarex NXG APX and it dropped squirrels and chipmunks as if they'd had a stroke. They didn't even twitch, well, one did, but that was because I sneezed as I pulled the trigger. I think that it's worth the $10 to try them. If the pellets were any heavier they'd be a slug. In my experience, which is limited, the higher speeds caused a loss of accuracy. The heaver pellets slowed them down and actually improved accuracy. Just my $.02.

http://www.pyramydair.com/s/p/JSB_Exact_Beast_Diabolo_177_Cal_Pellets_16_20_Grains_Domed_250ct/1197
http://smile.amazon.com/JSB-Exact-Diabolo-Pellets-Grains/dp/B00UXF0OJE/ref=sr_1_fkmr0_1?ie=UTF8&qid=1446580660&sr=8-1-fkmr0&keywords=jsb+beast+diablo


Or maybe these:
http://www.pyramydair.com/s/p/H_N_Sniper_Magnum_Pellets_177_Cal_15_Grains_Domed_300ct/1220
http://smile.amazon.com/Sniper-Magnum-Pellets-Grains-Domed/dp/B00TZOGVC8/ref=pd_sbs_200_2?ie=UTF8&dpID=41kvlCHkziL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=0GK5RYFP2NGAMNV78X00
 
theKevin, you mention you're looking at the Marauder. For the type of hunting you're planning, you might want to check out the Marauder Pistol in .22 caliber. It comes with a buttstock that turns it into a handy little carbine, but the whole package disassembles nicely and fits into a backpack. You will also want to attach a moderator (Wicked Air Rifles makes a nice one that's only 3.4" long) so that you don't spook the deer. A handpump works well to fill the pistol.
 
As explained above, if you stick with your Gamo, use pellets in the 10gr+ range to keep the velocity under 900fps.

The Marauder is an incredibly affordable way to get in to PCPs and may be so much fun you'll give up deer hunting. The repeater action plus accuracy and low report will have you hooked. The Marauder pistol is going to give you around 24 shots per fill and be a lot shorter and lighter than the rifle, but the Wicked Air Rifles shroud extension ($50) sounds like a must to quiet it down. The rifle in the same .22 caliber will give you 30+ shots per fill at a higher power than the pistol so you'll get a little more range from it. The rifle is plenty quiet in stock form.

For filling, I'd recommend skipping the pump and jumping straight to a tank. Used steel high pressure tanks (3500psi) go for $150-200, and have an effectively infinte lifespan unless abused. These are a great way to get started cheap. I got a HP100 for $150 and my only regret is that it wasn't an HP80 for the increased portability.

My .22 marauder rifle is tuned to shoot 14.3gr Crosman Premier Domes @820fps for 30 shots from 2400-1700psi. I get so many fills off the tank I can't even keep track, but the calculators tell me it should be about 65 fills. I ran the numbers for filling a Marauder pistol, and you'd be looking at about 65 fills from a HP80 tank filling from 2900-2100psi. Thats 1560 shots before you have to refill the tank, which usualy costs around $5.