My Mach 1 .22 loves the H and N FTT 14,66 gr. in 5.53 mm head size. When you master the shooting technique and find the pellet it likes you should be able to shoot ragged holes at 10 yards no larger that 3/8" on a regular basis. I started shooting mine a little over a year ago and I can tell you it took a lot of shooting to get to where I am today. IMO with only 250 pellets through it you have a ways to go to try to find that perfect pellet. I am far from expert but I will share some things I have learned with over 15000 pellets down the barrel, These guns are very hold sensitive. No one buys one of these for competition so I figure you will probably pest with it and maybe some hunting. If you master your technique off of a bench and expect to be able to shoot off of a set of shooting sticks you are in for a surprise. I have found that for me to do my most consistent shooting from session to session I use and open hand with the tip of my index finger in the cocking arm cutout. I use the trigger hand to do any control of the rifle. NO cheek weld and the stock only touches the shoulder with no pressure. You will know you have it when you can pick up the rifle and put the first shot spot on. If you start hitting left or right it is often cheek weld. Up and down is often where you position the rifle on the shoulder. I take those two out of the equation be using the pistol grip to adjust aim and rest the rifle in an open wrist. I practice off of a tripod with the gun in my hand. Another thing I have found with mine is if the groups open up I need to clean it. Now, IMO if you are just starting to learn forget about finding the perfect pellet for a while and buy some CPHP to hone your shills for a while. CPHP can be bought at Walmart for $6 a tin and will let you see how you are progressing. Some will be undersize and fall into the breech which may cause a flyer but many an airgunner started with them. Best of luck, Gary