Actually impressed with this pump and its construction. Purchased this to fill up a 68ci paintball tank to work on markers when too far away from the field. Originally thought this wouldn't fill a larger tank but was pleasantly surprised. Does it take a little while? sure. I would guess probably a total of 1.5 hours broken up to get a 68ci all the way to 4k.Some recommendations if you are buying this for something similar:- the pump will leak out of the box, it even says this in the manual. Take each fitting off and attach teflon tape and torque down properly. After spending 5 minutes doing this it has not leaked once and the guage is spot on. If this is difficult or an issue for you, maybe using a pump on a 4500 psi tank is something to be reconsidered.- take breaks with pumping. This is mostly for moisture control. Release the bleed valve after each pumping session and keep an eye on the filter on the hose.Ideally take it out and let it dry. I did about 500 psi at a time. The filter housing and moisture retention works well.- I will most likely break the pump down and do a more in depth maintainance interval as it has now proven it is a serious piece of kit worth the time.Overall I am very impressed with this pumps construction and modularity that is rare for something this cheap.

Worked very good, no problems but it's alot of work. After filling the tank 4 or 5 times. Decided to get the electric pump. :)

*BUYER BEWARE*Okay, overall I'm impressed... First of all out of the box it's absolutely NOT ready to roll, or pump... Its going to require a breakdown and proper cleaning/ lube job, nor is it filled with coolant. If you have any ideas on theory of operation and how pneumatics work it's an extremely simple concept to grasp and easy to preform the required work to get this pump up to shape in a jiff. However don't rely on the directions! Typical broken english crap that can't be understood. If you have issues working your way out of a shoe box or are just hesitant enlist the help of someone who has their mental and mechanical facilities in order (hard in today's society I know). That aside given the price some things are rough which is expected. Pieces will need additional work internally with scotch brite to eliminate burrs that will scar and tear o-rings. The internals are very dirty with grime and particulates from machining and obviously poor or no QC. The cylinder bores and valve assembly will desperately require a good cleaning. Instructions say coolant is in the pump... Um no it's not but obviously that's easily addressed. Use a quality o-ring lube and keep things VERY CLEAN. Also don't forget teflon tape on the pipe threaded connections!After a little TLC I'm extremely impressed with the pump. It is built hefty and feels like a solid piece of kit. High pressure is no joke and with my high expectations I feel very confident in the unit. After about an hours work you've got a pump that without a doubt doesn't break the bank and will give you many years of service WITH proper service so keep the service/ maintenance part in mind because no pump can go without regardless of price.Would I buy it again? Absolutely would! I knew it would require some amount of work and I was correct. Truly many of the bad nay sayers either A. Will not disassemble and properly go over the pump upon acquiring. B. They are negligent in the care and maintenance of a hand pump. Get one, clean her up and getting slinging some pellets!I wanted to update my review after putting this pump through it's paces over a weekend of shooting. Excellent pump! High pressure hand pumping isn't particularly enjoyable regardless of the pump. That said I'm just thrilled with it over all as it hasn't missed a beat. Properly serviced and coolant added it's a great tool to have when power to a compressor isn't pheasible. Still VERY happy with the pump overall. My one true gripe is merely a simple solution to fix. After periods of use the rubber grips affixed to the handle will back off the tube for which they reside but again, easy to remedy that. In the grand scheme of the pump I would certainly recommend it as a good hip pocket spare for your PCP game. Certainly NOT something you'll want to solely rely upon to fill permanently as hand pumping is a chore!

Worked for 2 months, snapped off at the connection between shaft and base. Factory flaw possibly? Company reached out and sent a replacement pump. I appreciate the company reaching out and trying to make this right. The pump itself works very well for charging an airgun.

It seems to pump up well and I'll test it a few times to make sure. I'll change this rating if it goes bad. I didn't have the hose tight enough when I first tried it, so my bad. Then I used the plug that comes with it for testing, and it works great. I like that it comes with the tool, extra O-rings and adapters. There are some videos that show how to change the O-ring on the valve inside the unit, and it looks easy to work on when the time comes.

This pump has been great, havent had a single issue. I have been "breaking it in" as described so it has the longest life. No moisture issues or leaks. It has a glow in the dark dial that I thought was pretty cool, didn't even realize it until I brought it back home and stored it.

Works well on a standard 48ci HPA tank. Haven’t filled one from empty, but it works well. The gauge does not match up to the one on the tank, so keep that in mind.I did what others here suggested and undid all the threaded connections and teflon taped them. The inside also has some metal shavings from manufacturing, but it does not affect anything I believe.

I wanted to like this pump - it seems sturdy, fit and finish are good, and it comes with a good kit of o-rings for repair (but no instructions on how to repair the pump). After setup and pressure check, I started filling my air rifle. When the pump got to about 3,000 PSI it started rebounding - it wouldn't go all the way down and it wanted to suck the plunger back down when pulled up. A FAQ in the user's guide indicated that the one-way valve might need cleaning. That was an understatement. Fortunately, a video on Amazon showed how to do this. I separated the shaft from the pump body and exposed the one-way valve. The thing was dripping with oil! See the attached photo. There was also oil down inside the pump body.I cleaned everything thoroughly and carefully reassembled the pump. It pumped better up to about 2,000 PSI when it started leaking air where the air hose attaches to the body. I tightened the hose connection a bit and tried again. This time it wouldn't hold air at all.Yes, I've seen the comments about putting pipe thread tape on the hose fitting to stop the leak, but I shouldn't have to do this on a pump right out of the box. As far as I'm concerned, that's a defect!Because of the oil-soaked one-way valve and the leaky fitting, I returned the pump. Clearly Four Uncles has some quality control issues.