Posted: 10/23/2002 7:51:48 AM EDT
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Hi folks, I have a CZ PCR (75BD). The rear sight is a Novak-style, not held in place by anything but the tightness of fit in its slot. I need to make a little adjustment to the sight. I don't want to start tapping away at the thing, hoping that I'll get it right by accident. I'm afraid I'l over or under do it and be trapped forever tapping it one way or another never getting it right, maybe wearing out or damaging the sight. Is there a trick to this? Is there a good way to gently nudge the sight? Can anyone recommend a jig or something? I'm mechanically minded, but I'm lazy and don't have a lot of tools to work with. |
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I hate to show my lack of sophistication here but I've always just tapped them using a brass rod and a small hammer. I mark a reference line on the sight and gun and use my public high school math skills to determine roughly how many thousandths I need to move the sight. Then I have someone hold the gun firmly to the bench if I am at the range or clamp it in my vise using non-marring wood if I'm at home and get to tapping. I've very rarely had to make two adjustments when I use the reference mark method. I think the trick is to pick your ammo and stay with that one kind. Then shoot lots of groups from the bench (3, 10 shot groups min.) using the same consistent hold on the target. If your groups aren't consistent you can't adjust accurately. The distance you move the rear sight = [distance you want to move impact on target (inches) * sight radius (inches)]/ distance to target (inches). Example: You want to move the point of impact 2 inches to the right at 25 yards; your sight radius is 8 inches. (2*8)/900=.0177 inches Make your index mark across the sight / dovetail interface with a pencil. Set your caliper for .018 inches. Start tapping the sight to the right. Tap & measure, tap and measure, until you have moved the sight about .017 to .018 inches. Go to the range try it out. If you measured the amount you wanted to shift the group accurately and measured your .018 inch movement accurately I'd bet money you won't have to tap again. (Hint: For more accurate measurements measure to the same edge of the index mark that appears on the sight and dovetail, i.e. don't estimate the center of the line.) Hope this helps, It's not a big deal. To me the only troublesome part is if the dovetail is really tight and you end up really having to spank the sight to move it. Good luck, Kent |
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Maybe I'm too picky, but I take the slide off the frame when drifting sights. Something about peening the rails (loosening)and jarring the innards sideways (springs popping off), not to mention less chance of an AD. Sometimes it may involve more trips to the range, bringing the targets home for reference each time, but it's a good excuse to sneak out of the house. 
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I've always locked the slide back and tapped away. The amount of stress I put on the slide rails and internals while tapping the sights is far less than touching off a .45 ACP and having the slide shuck open and closed again in a fraction of a second. (Should be no stress on the slide rails if the slide is supported when tapping.) Comments about the AD and sneaking out of the house I do agree with. In practice, if there are other people at the range that are not with me or I'm by myself I'll take it home to work on. If I'm at the range with my dad or a gun savvy friend I'll do it there. I don't have many fixed sight guns and I don't change loads very often so this issue comes up very rarely. Kent |
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There's tools you can buy that clamp onto the slide and let you adjust the sight with a knob. They're model-specific, though, and pretty expensive. It's hard to PRECISELY adjust the sights with a hammer and punch. Don't worry about any wear on the slide, though, as the sights are made of a much softer material than the slide. |