Out of elevation adjust?

[Mastiff37]

I've got a model 657 (41 mag N-frame) that I've been shooting off and on for a while. It's pretty close to point of aim at the close ranges I've been at (15 yards or less, light loads), but was hitting a little low, so I went to adjust it up and come to find that the rear sight is maxed out. I can go just a fraction of a turn before the threads on the adjust screw are free. Is there something stupid I might be doing here? If not, is there an easy fix, like a longer adjust screw or something? I did recently switch to a gold bead front sight, but it's the same height as the factory sight.

I know the light loads might be part of the problem here, but the thing that really brought this to my attention is that I got a laserlyte practice thing and it hits low too, so unless heavy loads actually cause the rounds to go up relative to barrel line of sight, something is up. Besides, this could be used for hunting at decent ranges and I'd expect the gun to be able to be sighted in at 50-100 yards with no issue.

 

[theoneff]

Where does it shoot at 25 to 50 yards

 

[Alk8944]

Either your front sight is higher than the original, or a previous owner installed a lower rear sight slide because he was shooting heavy-for-caliber bullets and couldn't get it low enough!

Run the rear sight slide all the way to the left, until the slide hangs outside the sight base. Measure the slide height with a dial caliper or micrometer. I can;t tell you for sure, but my recollection is that the slide should measure .160" +/-. There are basically 4 heights, .106", .126", .146", and .160". I will bet you have the .126! A hint. You need a slide high enough so that when zeroed for standard weight bullets (or the weight you are using) there is about .025-.035" clearance between the bottom of the sight base and the frame, measured at the rear of the sight.

Another possibility is you are shooting light-for-caliber bullets (you didn't say!), like 170 grain. If so then the fix is simple, get some 210-220 grain bullets and see how it shoots! This is the weight the cartridge was designed for and the sights are regulated for.

If you need to replace the sight slide call S&W, 800-331-0852. There are other retailers, but often S&W will ship at no cost, instead of the $6-12 charged by other sources. Order the full kit as you will need the nut and screw also, and it comes with instructions. Be sure to order a windage plunger and spring too, almost guaranteed you will lose them the first time you do this, and they are only a few cents.

HINT!! Emphasis intended. There are videos on "You Tube" showing how to replace the rear sight slide. At least the one done by Larry Potterfield (Midway USA) is WRONG. He tells you to turn the windage screw to the left until it breaks. If you do it this way the slide will be severely jammed in the sight base. The correct way is turn it to the RIGHT (tighten, clock-wise however you understand best) and everything will go easy from there on.

 

[Mastiff37]

Thanks for the great info. Looks like I have the .146 rear blade. So it seems a little mysterious still why I'm out of range. Do you happen to know typical heights of the front sights? Maybe that's extra short for some reason, though it doesn't look short.

I'll need to get back to the range and be more scientific about how far off I am. I was mostly surprised that I was nearly maxed out when shooting at such short ranges.

 

[BLUEDOT37]

Do you happen to know typical heights of the front sights?

My 657-5, 7-1/2" bbl. had a .243" front sight & a .146" rear sight on it.

What rev model & barrel length is yours?

.

 

[silentflyer]

If you disassemble the rear sight assy., get a large clear plastic bag big enough to cover the gun and take it apart inside the bag. Beats crawling around on the floor looking for all those small parts. Trust me I learned the hard way.

 

[Pisgah]

Try the gun with with magnum loads. The sights are designed for use with loads that feature bullets within a certain weight range, launched within a certain velocity range. If your bullets are too light and/or velocity too low, the standard front sight may well be too tall. Conversely, if you went to a heavy-bullet load with magnum velocities, it might be too short!

 

[H Richard]

Do you still have the original front sight? If so, measure it and the replacement front sight. I purchased a 16-4 a couple years ago and the front sight had been replaced with a gold bead target sight, but it was nearly .030" taller than the original. I purchased an original and put it back the way it should be.

 

[MichiganScott]

Use a heavier bullet. Years ago I got the bright idea of using my 8.375" Model 29 for deer hunting with a 180gr bullet. I could not zero the gun because it shot low with the rear sight all the way up. I finally ended up using a 240gr LSWC like Elmer Keith intended.

You can probably get by with using the 210gr bullet at reduced velocity; just not reduced too much.

 

[arjay]

Light bullets/higher velocity hit much lower than heavy bullets/slower velocity.