How to tune a Bobcat MK2 .25 cal?

Vudong, after problem is solved please come back to this string and post the corrective action. I try to learn from these posts. Those fellows will get you shooting out snake eyes again. I like that .30 cal group also. Have a good evening.

Robert

I have not had this problem with the same rifle but it sounds like you added the LDC. I would look there first. Next sort some pellets to eliminate bent skirts or deformed. You could go as far as head size as well but at least get some good looking pellets for your testing. 
My biggest problem with the Bobcat MK2 when I first began shooting was canting of the rifle and practiced trigger pull (breath and squeeze). Put a bubble level on it and make darn sure it is level with the scope / rifle. Some of the add on bubbles when tightened will cant during installation.
All the advice above is good as well, but if the rifle shot well when you first got it then something added to the rifle has degraded or moved.
Good luck and keep us in the loop.

If it is clipping you will not get a consistent 3 or 4 shots and then a couple off, then a few consistent and a couple off. If clipping is occurring it will effect your groups and open them up completely. When you clip a baffle or end cap it causes very inconstant groups, you won't consistently get a nice group and then a few off. I have had this happen with my own shooting and have attributed it to my rushing the shots, or not having my breathing or trigger pull correct. I don't automatically think there is a problem with the gun. Many experienced shooters will tell you, a few fliers can often be shooter problems and not guns problems, Just my 2 cents for what it is worth, Neil.

Glad to hear you have it back and all is well.