N/A Why would it shoot two groups?

[Caliber 22]

My rifle used to shoot one hole groups at 25 meter and good groups at longer distances up to 100 meter. Now that was with a certain batch of pellets that is finished I don't get the same anymore. It still shoot one hole groups at 25 meter but it is split in two groups. It would shoot a few pellets through one hole, then the next few shots about 8mm higher and then back to the first hole again. The chronograph show the SD is about 5 -7 and ES about 18, but the high or low shots does not correlate to the speed.

It is a M22 in 5.5mm.
I checked and everything is tight. I tried another scope as well but it still do the same.

Does anybody has experience with such a problem? What would cause it?

 

[TimeRabbit]

What pellets are being used?

 

[thomasair]

Stock bedding, or the lack of it causes fun stuff like this. Most airguns have no semblance of bedding.

Mike

 

[Caliber 22]

Stock bedding, or the lack of it causes fun stuff like this. Most airguns have no semblance of bedding.

Mike

Since I asked this question I did not get time to check out my M22 until this weekend. I removed the stock and saw that when I last removed it to do some maintenance I somehow forgot to put back the front spacer I used to have in there before. Well I put back in the spacer and did a few test shots, 10 shots through one 8mm hole without shifting as before asking above. 15mm 5 shot group at 50 meter and 45mm 5 shot group at 100 meter. Thanks for the tip.

 

[muradtexas]

Stock bedding, or the lack of it causes fun stuff like this. Most airguns have no semblance of bedding.

Mike

Thank you. I was wondering about my groups walking around. It wasn't bedding, but it gave me an idea to try shooting my gun off my backpack instead of a bipod. Groups tightened up immediately.