mounting iron sights
I'm putting a Centra Microsight on a Savage 10BA. I'm using a barrel clamp for the front globe sight. Now the problem. The front sight riser block. The ballistic charts give me a 4.2 to 4.4 drop at 200 yards, with a 1.5" drop at muzzle, 0.0 at 100 yards. How to select the right height block? If I try to bore sight, the laser can't be seen at 200 yards. (I don't have a 200 yard area to set it up either). I have a wall in my house to set it up. How high/low should the sight picture vary from the boresight laser?
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1.5" drop at muzzle indicates that the line going from rear sight to top of the front sight is 1.5" above the centerline of the bore. Time to do some measuring... 0 -
The distance from the sight center to the bore of the rifle isn't the problem. That can be measured. At 100 yards, the bullet has already been lobed over the line of sight and has intersected it the second time at point of impact. At 200 yards it needs to be lobed another 4 inches higher. So, the axis of the barrel would need to be canted up at the front, a front riser shorter than the height of the rear sight. How much? Since laser bore sighting can't effectively be done, there must be a way of doing it other than buying multiple height risers in a guess scenario. If you start with the wrong height in the first (or second, or third) place, you would probably go thru 50 -[:D] 100 rounds and not even hit the paper. If I took it to a Gunsmith, he must have a way of hitting the paper the first time. [:D] 0 -
Most scope centerfire (1.5") rifles will cut the paper at the same point at 25 yard as they do at 200. Do your laser at the shorter range, use modelling clay to hold the front sight. Squish it in until it lines up. Check debth of clay with dial caliper.
A trajectory table for your load that has the nearer distances would be helpful. The distance between the front and rear is important too.0 -
greybeard100,
Measure from the sighting point of the front sight, to the center of your bore. That is the sight height you will use. If you need to raise it 4 inches(or 2MOA) at 200 yards, use the rear sight to do this. IF you raise your front sight with a riser, then your point of impact will be lower yet. You never did say what you are using for a rear sight.
As for a laser bore sighter, or what most folks call a bore sighter, that you stick in the end of the barrel, the best place for them is left in the drawer, or put in the garbage can. Remove your bolt from the rifle, and LOOK thru the bore! That is bore siting. Bore sight at about 20-25 feet on a target, lookiing thru the bore. Make sure the rifle is on a solid rest, center the target in the bore...then adjust your sights to the target. That is bore sighting, and should put you on the paper at 25 yards. I'm not saying it can't be done, but asking to be on a sheet of paper at 100 yards from bore sighting is hit or miss, and can be frustrating. If you center your shots at 25 yards, you will be on the paper at 100.
Lastly, even though they might be close, don't rely on your published drop charts, until you prove them out. Never shoot at distant game, until you prove out your system at that distance.
Any more questions, feel free to e-mail me.
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Charliemeyer007 has a good idea with the clay.
TSR1965 - I did say I was putting a Centra microsight on the rear (and a Redfield globe on the front). In discussing this, I have come to the conclusion though, that if I set up the sight picture exactly parallel to the bore, the shot should be approx. 4.2" low, which IS on the paper and can work from there. I could also set the rear sight a little lower than mid-point because I know it would need to be raised.
A riser block has the dove-tail that the globe mounts on and the screw holes to attach to the barrel. It's required to mount the globe to the rifle. The size of the (height) riser is variable from 0.250" to about 0.750" (or more). I was just trying to figure out how to find the right one.0
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