Jerry, I have two .40's with swamped bbls. The first has a Getz "A" weight 42" bbl. It is 15/16" at the breech and .705" in the waist. All three of the underlugs are dovetailed .030" deep. The one at the muzzle is 3 3/4" back from the end, while the waist is 6 - 10" back from the muzzle, so there's plenty of steel there for a dovetail. The other is a Rice "B" weight 44" bbl. and it is thicker yet. Both of these rifles are wonderfully accurate and I have had no issues with warping or bending. Are you sure of the waist measurement on your bbl? Seems a little light??