Point of Original Impact on 40X HB

E

ehkempf

Guest
I have a question that some of you may have experienced and might have a plausible answer. I like many of you could not resist the 40-X’s that were being sold by the CMP. I bought two HB’s, got one still waiting on the other. I also own a 40 XRBR that I bought back in 1999. The XRBR has a Leupold 36X BR scope (black) mounted in Kelbly rings with Davidson bases (silver). I have a spare 36X BR scope (silver) that I was going to mount on the 40X HB. I bought from Kelbly a set of black rings and bases (their bases are just like the Davidson). Well to make a long story short I decided to swap the black scope from my XRBR and use that on the 40X HB, and use the silver one on the XRBR. I made sure that both scopes were set back to optical center. I sighted the XRBR in first. I shoot at 50 yards and I am using Federal 900B (1080 FPS). The point of impact was basically 9” low and 9” to the left. The XRBR has a 24” barrel. I then sighted in the 40X HB, and guess what, it also impacted at basically 9” low and 9” to the left. It has the original 28” barrel. I was also using the same ammo. Now my questions: I would expect the shots being low, maybe not 9” (that might be also because the Kelbly rings and bases mount a scope higher than say a weaver base and rings), but why the 9” to the left. The fact that it did this on both setups is what has me puzzled (it may have been that way when I originally sighted in the XRBR but that was over 10 years ago). Several months ago I sold a 40X SB to a fellow club shooter and when I originally sighted that gun in (using weaver bases and Leupold rings) it also shot to the left. So is this common with 40X’s? By the way that 40X HB with the Federal 900B shots right up there with my XRBR, it easily produced 5 shot groups in the low .2’s. Not bad for a rifle that is 46 years old. To bad 900B is not available any more.

Sorry for the long post.

Ed
 
I've got one that I have to use windage adjustable bases(burris Signature with 20 moa, or Leupold rear adj) because the base holes are off center. I'm told that it is somewhat common. Rgards
 
I use Burris Signature rings on mine for the same reason.
 
I've found that with most.............

centerfire rifles, when you neutralize the adjustments they are too far to the left when mounted, using the collimator. I've taken to "reading" the 'scope after its sighted in, and they are typically one square(4") to the left, and anywhere from 1/2 a square to two squares below the horizontal wire on the collimator. Now, with the rings I use, I go ahead and get my rough windage dialed in(using the ring) one square to the left, and crank the elevation down at least one square, depending upon velocity. With a .22RF, you may have to crank it lower. Good Luck :)
 
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