Solved: Rear dovetail out of spec on factory new 2.0 45 slide?

asilcot

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I purchased a new M&P 2.0 45 FDE stripped slide (3008858) to set up with suppressor sights. I did not want to remove the factory TFX sights on my 45 so I ordered the extra slide. I finally got all of the parts together and assembled the slide today. I removed the sights from the package and checked the fit. The front was nowhere near starting in and would have to be fitted. But the rear was a different story. I could slide it all the way through by hand. The sights are Dawson Precision so I called them. They had me measure the width of the rear sight base and confirmed that mine is correct (.469"). They concluded that the dovetail on the new slide is out of spec.

I can return the slide if it is defective but it now shows out of stock so no replacement is available at this time. If the dovetail is incorrectly cut it would not help to order a different set of sights. Has anyone run across this before? Any suggestions?
 
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You could measure your new slides mill cuts and see if dawson can send different sights or can they fit them .
 
If you want to fix it you can put a thin shim stocking the bottom of the dovetail. This will raise the sight base in the dovetail and tighten it. You can finish the ends of the shim after it is fitted or leave it bright so posterity will know it is there
 
You could measure your new slides mill cuts and see if dawson can send different sights or can they fit them .

I called and they checked several of the other in stock sights. All measured the same as the one I have. They can custom make a sight to fit but it gets a lot more expensive to go that route. I may try a shim first.
 
If you want to fix it you can put a thin shim stocking the bottom of the dovetail. This will raise the sight base in the dovetail and tighten it. You can finish the ends of the shim after it is fitted or leave it bright so posterity will know it is there

I called the local hardware store and they have a small pack of shim stock running from .001" to .005". They are 3x4 inch sheets and only a few bucks for the pack. I will go down after lunch and pick that up. That is so thin that I could just trim it off at the end of the sight with a razor blade. Will post results later. Thanks
 
If you want to fix it you can put a thin shim stocking the bottom of the dovetail. This will raise the sight base in the dovetail and tighten it. You can finish the ends of the shim after it is fitted or leave it bright so posterity will know it is there

This reminds me of the necessity to think---carefully and thoroughly about any and everything that at least seems to be a problem---at first.

Once upon a time, a looooooooong time ago, my racing partner and I had decided to add the latest demon tweak to our car. Now my partner had a Masters Degree in Mechanical Engineering, so he'd already learned about thinking ---carefully and thoroughly---about there being more than one way to skin a cat. I hadn't---in spite of his ongoing best efforts to beat it in to my skull.

The demon tweak was a rear "sway bar". It's to attach to the frame at one end, and to what I'll just call the suspension at the other. I had it in my hands while laying on a "creeper" under the car. The gas tank was in the way at the points where it was to attach to the frame. I called out, saying we were going to have to move the gas tank. He glanced under the car, reached down, grabbed my ankles, and yanked me out from under the car----muttering scathing and unkind comments about moving the gas tank. Down under he went-----and back out-----in a matter of seconds. "See what you think of that!!", he said. He had simply flipped the bar, front to back---and now the gas tank wasn't even close to being in the way.

Now, much as I hate to admit it, my first Bubba thought to solve this dilemma here was to peen down the upper portions of the dovetail (call it a knee-jerk reaction)---never mind the mere thought of such a thing made my teeth hurt---A LOT!!

I most certainly wouldn't have done that, but thank God for the other folks who think first!

Ralph Tremaine
 
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This reminds me of the necessity to think---carefully and thoroughly about any and everything that at least seems to be a problem---at first.

Now, much as I hate to admit it, my first Bubba thought to solve this dilemma here was to peen down the upper portions of the dovetail (call it a knee-jerk reaction)---never mind the mere thought of such a thing made my teeth hurt---A LOT!!

I most certainly wouldn't have done that, but thank God for the other folks who think first!

Ralph Tremaine

My first thought was to peen the underside of the sight. I have done that in the past and it worked. I dismissed that idea in this case because of the striker safety location. I never thought about peening the upper side.

The shim crossed my mind as well but after watching Dawson's installation video, how tight it should fit and then use Loctite in the dovetail, I was hesitant to do that. I just got back from the hardware store so I guess I will try that. The fact that a local store has in stock an assortment of 3x4" brass shim in .001, .002, .003 and .005" thicknesses for five bucks may be an omen.

By the way, I also considered trying a set of Trijicon sights to see if they fit any better but I called them and they gave me a measurement that was .013" smaller than the Dawson. I am thinking they could be thicker at the base which would tighten the fit but they said no, they just fit the standard S&W dovetail.
 
Well, at least the shim crossed your mind; so you're aware of the fact there's more than one way to skin a cat.

To this day, I'll tend to lock on to my first thought, and have to force myself to keep on thinking. The good news is, by this time I'm at least aware of the fact I need to keep on thinking.

Ralph Tremaine
 
Quick update on this. I called the distributor that I bought the slide from. He said he has another one on order and it should be in late next week. I am sending this one back to him today.

No need to patch a brand new project if a proper solution is available. Thanks for the help.
 
Quick update on this. I called the distributor that I bought the slide from. He said he has another one on order and it should be in late next week. I am sending this one back to him today.

No need to patch a brand new project if a proper solution is available. Thanks for the help.

Good luck & please follow up with us when the new slide arrives. Hopefully it’ll be in spec
 
The distributor called me when he got the slide back. He said that he pulled a new factory rear sight from stock and it will not go into the dovetail without fitting. I called Brownells to confirm that I could return a set of Trijicon suppressor sights (unmodified) if they did not fit. I ordered them and called the distributor back and asked him to return the slide to me. I got the slide Saturday and the sights came in today. I took somewhere between .001 and .002" off of each sight and drifted them in. Good solid fit on both of them.

I suspect that this was a case of tolerance stacking. The slide a little on the large side but within tolerance. The first rear sight just a little under but within tolerance. I am fairly certain that another thousandth or so between the two of them in the right direction and it would have been a great fit. Either way, problem solved.

Thanks for the help and your suggestions.
 

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