How much difference does .040" make?

[tpcollins]

I was looking at my Ultra Slug and noticed the scope tube seemed closer to one side than the other. I removed the scope and measured the base - same issue. I pulled the base and found that the (3) tapped holes in the barrel are about .040" right of center.

The gun shoots ok but since the scope's mounted on the right of center, the crosshairs must be aiming left to hit the 100 yard target and I'm wondering what's the poi at 150 yards?

I have Burris Signature rings and I could install a set of .020" offset Posi-Aligns on the front and rear but that only fixes half. I think it has a Weaver base and maybe I could turn it around 180 degrees and have (3) new holes drilled .040" to the right of center.

Or is .040" nothing to get excited about? Thanks.

(I suppose I could lean the retcile to the right and then just cant the gun to the left to shoot straight . . . )

[Creeper]

I suppose I could lean the retcile to the right and then just cant the gun to the left to shoot straight

Ta Da! Everything is perfectly aligned... but the entire rest of the gun.

Or is .040" nothing to get excited about?

Seriously, with a relatively limited range slug gun... unless you're running out of windage adjustment, or due to poor machining the scope is in a bind in it's rings, it's not that big a deal.

Cheers,
C

[hoghunting]

I have Burris Signature rings and I could install a set of .020" offset Posi-Aligns on the front and rear but that only fixes half

That's how I would correct it, and .020 offset on the front, then .020 offset on the rear is .040 correction.

[tpcollins]

That's how I would correct it, and .020 offset on the front, then .020 offset on the rear is .040 correction.

I'm not sure that would work. I got to thinking about this and if the scope is aligned .040" to the right and is centered and parallel to the bore, it should hit .040" to the right at 100 yards or 500 yards - makes sense to me at least.

I got to playing with it some more since I had to skew my Leupold Zero Point to the left side of the barrel. I played with the scope and when I turned the windage to the right, it tracked nicely along the little Leupold graph. But when I turned it to the left, it did not move the last 1 1/4 turns or about 75 clicks. I assume my scope is screwed up . . . ?