About 6 months ago, I tried a similar 'trick'. I placed 2 pieces of rubber fuel line in the forend. The tops were cut in a "V" shape to position the bbl in the center of this pos stock.
I tried several groups with the tubing, then without, again and again. Group size was the same. Only change was POI change.

As an additional comment, I taught a new shooter to fire a rifle yesterday. I picked my M25 in .17 Hornet. I had almost forgotten how sweet a little ctg it is! And it's reloadable to boot.

The BMag has been a big disappointment.

ron