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 Post subject: A better mouse trap
PostPosted: Thu Oct 05, 2017 4:57 am 
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Posts: 1311
Location: Kennesaw, GA
For years now, I have taken every pistol that I did any sight work to the indoor range about 30 minutes from me and test fired to zero the sights. I have always "pre-zeroed" using an in barrel laser that most of the time gets you pretty close, like within an inch of a little more at 15 yards. Then I would try various things to try to get the windage absolutely on the money, either by whacking with a non-marring hammer, or using a sight pusher. The problem was that I had no vise to use and didn't want to take my Starrett depth mic with me, so I'd whack or crank on the pusher and who knew where I was going to end up. I had to shoot another group to see what I had done. Sometimes, I thought I'd moved the sight and the group was in the same place and sometimes I moved the group and inch and a half to the other side of zero! I know, if this and if that, but that was all I had to work with. And I really didn't have much more success with my sight pusher. All I could tell was that I turned the forcing screw so many degrees past the contact point and that should be a movement of so and so. That wasn't so hot either. I finally just shot a group, took the guns back to the shop, put the slides in a vise, measured from one side of the slide to the side of the sight with a depth mic and then drifted it with a hammer and punch until I was where the correction formula told me I needed to be. Then back to the range. Sometimes in the same day, if I was in rush to get thte pistol finished and shipped as agreed. So hours of travel time and range fees were really bumming me out.

Then, as Chef Emeril says - BAM! I had an idea. (a rare occurrence) I thought how great it would work to have a dial indicator against the opposite side of the sight from the forcing screw. I could actually read the sight movement as it occured. I saw a way to modify the side link bar of the P-500 sight pusher to mount an indicator with a 3/8" stem and away I went for a test drive.

With no disrespect intended to anyone in the sight pusher business, this indicator set up works like a dream. Now I can really see what movement to the sight has actually happened without estimating how much of a turn I made on an allen wrench and whether the sight really moved that much. I have also had sights jump unexpectedly and all I can do at the range is to reassemble the gun and shoot another group. This way if your calculations to correct impact say you need .013" you can see the sight move .013" and then relax the forcing screw and be sure it stayed there.

Now I don't have to keep taking the gun apart, guess at what I've done, reassemble, shoot a group and repeat; ad nauseam. It saves me both time spent at the range, extra range fees, ammo wasted and extra trips to the range, none of which put money in a gunsmith wallet.


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An addendum to above post:

I spent a little more time with the sight pusher / dial indicator after Georgia got finished trouncing Tennessee yesterday and learned a couple of things I thought I'd share.

After I had "pushed" the sight over the .010" you see on the indicator in the pictures, I rushed to the man cave to see the kick off. When I came back after the game, I decided to back off the forcing screw and verify that the sight stayed in place. It did not. It showed only .002" change in position from "0.00", the original position.

I thought hmmmm, this is not desirable, so I started to crank down the forcing screw until I had .020" "movement showing and backed off. Again, no joy, only that .002" change.

So me being me, I cranked down the screw further until I was at .030" "movement", then .035" and finally .040". Then I heard a audible "snap" and I said oh crap, I broke something.

Noooop, just the sight finally coming loose and moving. All that "movement" I thought I was seeing was just flex in the fixture as I cranked down the screw. Those screws can transfer a really significant pushing force and that sight was the original Colt rear sight on a 32 year old Delta Elite.

So after that snap, I backed off the screw again and it had actually moved .027" from zero. So I had to reverse the mounting of the fixtures bridge to be able to push in the opposite direction (remove two screws, turn bridge and reinstall screws) and then I moved it back .017" to get that desired .010" change from zero that I wanted to start with. Loosened forcing screw and it stayed at .010". Yay!

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 Post subject: Re: A better mouse trap
PostPosted: Thu Oct 05, 2017 7:36 am 
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Joined: Fri Feb 20, 2004 5:30 pm
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Location: MI
Excellent! Yes, always nice to know how much. I think the only thing lacking in that setup is extreme rigidity. I wonder if making new side pieces at twice the thickness would do it?


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 Post subject: Re: A better mouse trap
PostPosted: Thu Oct 05, 2017 1:30 pm 
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Joined: Fri Feb 20, 2004 8:16 am
Posts: 2086
Location: Gilbert, AZ
Awesome, John. Very well thought out!

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 Post subject: Re: A better mouse trap
PostPosted: Sat Oct 14, 2017 5:55 pm 
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Joined: Mon Apr 17, 2006 11:16 am
Posts: 62
As a metrologist and a BIG fan of your parts....

I SALUTE YOU, SIR!!!

That was a BRILLIANT idea!!!!

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