[lurkingknight]

in terms of a bushing, any size performs the same, where the sizing on this issue matters is a bearing.

The larger, the stronger it will be due to the ball bearing size, but the larger the bearing assembly gets, the wider it will sit, and some gearboxes and receivers have issues fitting larger bearings.

People round here will argue against this, but I am an advocate of epoxying bushings into the gearbox shell. This takes up the slop the bearing might have side to side that might throw off shimming and it will also prevent the bushing from spinning in place which can lead to the holes being enlarged and bushing to fit looser or heaven forbid so much slop is introduced that your gear meshing becomes affected.


Bearings can slightly increase your rounds per second (I measured 2 or 4 rps in 7mm CA bearings to bushings in my g36), but at the cost of reliability. Also if you're not used to the free spinning nature of bearings, they can mislead you to thinking you have a good shim job when in fact it might be too tight. I've had 7mm bearings fly apart.. the races just self destructed and the spur plowed into the side of the gearbox shell gouging it and grinding some teeth on the sector and spur. You'll never see that with a bushing.