The ammo used for the test shooting were Copperhead BB's . The above is a shot of a random sample of brand new Copperheads compared to some lead BB's I was given . Note the large pit in the middle Copperhead . I have not tried any of the lead BB's as they are not suitable for this pistol .

The following are sizes taken from a random sample of the two different BB types to compare for manufacturing tolerances .

As you can see , with the Copperheads being so small there would be an even greater differculty in getting an accurate grouping . I have been advised that the BB should be between 4.34mm to 4.47mm and I would assume that the closer to 4.47mm you can get the better .