Adjusting a drift sight

[Brians356]

I want to drift a rear sight .020". I know how to drift it, the old-fashioned way, but not a pre-determined distance.

Suppose I take it to someone with a proper sight pusher. Can one count turns (and fractions) and dial a push very close to, say, .020" on those devices? Or are they just a smoother, safer way to nudge the sight along "a little bit" or "a good bit" at a time, requiring either reiterative checking with a dial indicator fixture, or by shooting a target?
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[tobnpr]

Can one count turns (and fractions) and dial a push very close to, say, .020" on those devices?

No reason it shouldn't work that way...
You need to know the pitch of the adjusting screw, then you'll know approx. how many degrees rotation of the screw that will advance the pusher the desired distance.

 

[Brians356]

No reason it shouldn't work that way...
You need to know the pitch of the adjusting screw, then you'll know approx. how many degrees rotation of the screw that will advance the pusher the desired distance.

That's how I figured, but thought maybe inherent limitations due to backlash or whatever. It doesn't need to be gnat's ass to shift a pistol group's center, obviously, but I'd like a reasonable chance to drift it once and be where I want to be on target.
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[tobnpr]

If you have a padded vise to rigidly clamp the muzzle, and if you have an indicator and can position it against the front sight blade somehow, you can measure the shift precisely.

"If, if, if..."

 

[Dusty Stevens]

You can probably find a spot to measure then use a brass punch

 

[Will Henry]

I'm assuming the sight is in a base? If so a punch with an adjustable collar which contacts the base should do. A sight pusher can work but there is always some spring if the sight is tight at all. A loose dovetail with a lock screw makes things easier. WH

 

[Brians356]

I'm assuming the sight is in a base? If so a punch with an adjustable collar which contacts the base should do. A sight pusher can work but there is always some spring if the sight is tight at all. A loose dovetail with a lock screw makes things easier. WH

The rear "base" is a dovetail in the slide itself. The top corners of the slide are 45 angles. Look at any Springfield Hellcat photo online.
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[Will Henry]

OK. I looked at the website. I would make a close fitting fixture which straddles the slide and encompasses the sight. This fixture could than have a hole which aligns the aforementioned punch with collar; or it could be fitted with a threaded pusher. WH

 

[Brians356]

Thanks, Will. Well I won't be making any fixture. I called a local 'smith and we talked it over. Piece 'o cake, he said, if I know how far I want to move it. He has a fixture for a dial indicator to witness everything, but uses a brass punch and his skill with it to sneak up on it in only a few iterations. I can use a punch, sure, but have no feel such as one acquires after years of practice on a task like this. I'd be overshooting, back and forth, no doubt.
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[Will Henry]

Thanks, Will. Well I won't be making any fixture. I called a local 'smith and we talked it over. Piece 'o cake, he said, if I know how far I want to move it. He has a fixture for a dial indicator to witness everything, but uses a brass punch and his skill with it to sneak up on it in only a few iterations. I can use a punch, sure, but have no feel such as one acquires after years of practice on a task like this. I'd be overshooting, back and forth, no doubt.
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So would I! WH

 

[Brians356]

Update: I took it to a local 'smith and in 5 minutes he drifted the rear sight to my specified .020". Cost was $35 but as a business owner myself, in a high cost-of-living locale, I don't begrudge him that. Ain't nothing cheap anymore. He did ask if I had brought any witness targets, which I had done, the best 5-shot group from two different loads. I actually appreciated that he checked my calculation rather than just saluting and taking the money, and no offense taken here.
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