I am also fairly new at this. The first rifle I bought was an AEA Megalodon. Get your self a handpump to use in a “have to “case, like when your electricity is out due to a storm or something. You won’t pump any guns pressure tanks up to 4500psi. There are small high pressure compressors that use 12 volt DC motors for less than 200 bucks. they are best powered from a vehicle battery. They have 110 volt units that make 12voltDC , imo they don’t make sufficient power to run compressors. For slightly less than 300 bucks you can get a high pressure air pump, more trouble due to being water cooled but not that big of a deal to use. They are fast, it takes a small compressor 15 to 20 minutes to pump my .6 liters tanks from 2500 to 4500 psi. It take the high pressure air pump I recently got 3 1/2 minutes to do the same thing. If you wish to hand pump your gun you should go with something other than 4500 psi. Maybe 3000psi would be manageable, barely also be prepared to service the hand pump often, get a the seals and stuff to repair it when it stops pumping. I would like to recommend you get a Megalodon, it is an awesome super fun airgun to use, however at least my specific rifle has this valve lock thing it will do when you do exactly what you were asking could you do. Leaving it setting with pressure near the max and when you go to shoot it you get a half power shot that barely gets the slug or pellet out of the barrel. I’m going to test it and see if a lower pressure won’t valve lock. Otherwise I would have to shoot it before I head to a stand or hunting spot to be sure that first shot from the stand would be a full power shot. I have a 50 cal , 8 round mags, pump action and the stroke to work action is very short, you can repeat shoot it as fast as you can cycle the action. It will produce 2 mags worth of quite lethal shots from a full charge of air and that leaves 2500 psi in the tanks. Dual tank gun with a rear tank acting as part of the stock , that tank can be removed by unscrewing from the gun leaving you with a long barreled pistol sort of, the tank does not degas when you remove it and neither does the gun. The gun will work then off the front tank just like a single tank gun , when your ready for your stock back you screw it back on and you have that air to use again. If not for the valve lock thing happening it would be a perfect hunting gun. I’m going to hunt with it, I will just shoot it into the ground before I leave the house. I’m the mean time I may try replacing hammer spring or something. Be warned , AEA and Bintec are coming from AEA I believe, the guns do not come with anykind of manual. You have you watch YouTube videos and basically figure it out. Pick a good shop to buy from if you decide to go with either brand, they will help you get going properly. I got my stuff from Bluegrass Big Bore and they gave me excellent customer service. AEA makes a single shot side lever action rifle called Element, it can easily be modified by the shop to have the same rear tank set up as the Megalodon but it’s just single shot. I was going to go that way but ultimately choose the Megalodone. To spite the valve lock issue I couldn’t be happier with it, I shoot it nearly everyday, I plink with .495 round lead ball ammo for like 12 cents per shot. They cycle through mags perfectly. I would check you tube and comb through big bore airgun reviews , I seen a great looking riflethat was .457 and the reviewer shot a bottle cap off the top of an inflated ballon without breaking the ballon. He was keyhole grouping with it out to fifty yards and was knocking down 8 inch steel plates at 200 yards. I’m sorry I don’t remember the name of the rifle, I will try to find the video and message you where to find it. I should also mention after you get into this , your also going to want a tank , so you can quickly air you gun in the field or tether to it when you bench shoot it. I’m 200 bucks into getting that set up , I just need one more 50 dollar valve and I will be able to fill a carbon fiber 4.7 liter tank to 4500 to air up my rifle anywhere I may have it. If you don’t want a compressor or air pump you should go with a regulated gun the tops off at 3000 max, and that won’t be fun to pump up to, but it is possible. I hope something in all that helps. just trying to give you a glimps of what your in for, don’t get me wrong though, I have zero regrets up to this point. The air gun is somewhere between a muzzle loader and a compound bow is the best way i can describe it in terms that might click for you. the round is way faster than a bow, but slower than a muzzle loader. A 100 yard shot has more hang time than you expect it to , but it gets there and slams the target hard, at least at 50 caliber it does. Good luck my friend, I hope you have as much fun as I have had.
Jim