+1

I fired my 15-22 almost exclusively using a bipod the first couple of months I owned it. I was a little disappointed in the accuracy until I started trying various ammo brands, velocities, etc. Eventually I got sick of using the bipod and took it off and started to fire sandbag supported. I noticed an immediate improvement in consistency and group tightness.

Here's my theory...

With a bipod rigidly connected to the bottom rail of the handguard, adjusting the sight picture by simply moving the rifle was torquing the handguard left/right by varying amounts. Since the bipod feet were remaining stationary, the movement of the rear of the rifle was putting inconsistent stress on the handguard and in turn on the barrel.

At 50 & 100 yards, even a slight movement will be noticeable.

Using sandbags or another support will still place a small amount of upward torque on your barrel, but it will at least be consistent. Adjusting the sight picture by moving the rear of the rifle will no longer torque the handguard left/right because it won't be connected to anything and should be resting in your palm with an almost nonexistent grip.

That's my 2 cents...