Shorter front sight

[DustyW]

I've read the thread about the Pro shooting low, which mine does. 115 and 124 gr. 9mm bullets shoot extremely low. I had 2 other people shoot it with the same results. I have some 147's loaded to try, but I'd really like to shoot a lighter bullet, mainly because they are cheaper. So, avoiding the adjustable rear sight, what size front sight would you try to raise the POI. I think the factory height is .180". Would a .160 raise the POI very much? The 124's shoot about 6-8 inches low at 20 yards.

Edited December 25, 2010 by DustyW

[G-ManBart]

6-8" is a lot....I'm not sure if a .160" front would raise it that much. Someone posted the formula for determining how much a change would equal...I'll see if I can find it, but it's here in the M&P section.

This isn't the thread, but this post (and thread) has some detailed info:

http://www.brianenos.com/forums/index.php?showtopic=108936&view=findpost&p=1282989

Edited December 25, 2010 by G-ManBart

[Cy Soto]

Here's the formula G-man is talking about:

To determine the correct sight height to correct an elevation problem, multiply the sight radius, in decimals by the elevation error and then divide the results by the distance to the target, in inches.

Sight radius 5 3/4" = 5.75

Shooting 5 inches low

Distance to target 25 feet or 300 inches

(5.75*5)/300 = .095833333.................3

The front sight would have to be lowered .096 or the rear sight raised that amount (or a combination there of) to raise the point of impact.

[High Lord Gomer]

...or, to figure out what effect a change in sight height will have in POI:

Sight Change / Sight Radius * Distance to Target = POI Change

Swapping from a .180 to .160 and shooting at 20 yards (720 inches):

.02 / 5.75 * 720 = 2.5" change

[mpeltier]

Wow 6-8 inches is a lot. My 4" M&P shoots exactly to point of aim, and my pro shoots only about 1/2" to 1" lower than it. (with 124gr). You might see what Smith & Wesson says about it first. Their customer service is pretty good.

[Classic_jon]

That is exactly what my M&P pro was doing and if you read the last post on the thread G-man Bart linked they did put a shorter sight on mine.

Now that the holidays are over, I should be headed out to the range this Thursday or Saturday to test it and see if the shorter sight has helped with the issue.

[Adam P.]

My M&P 9 had this same issue. I sent it back to Smith and they replaced the barrel. It went from 7" low to 3" low at 25 yards with 124gr bullets. I tried 147gr bullets and had the same results. I contacted Smith again and sent the gun back again. This time they called me and told me it was my problem and not the gun. I got the gun back, put it in a ransom rest and still got the same results. Contacted Smith again, but they stood by their remarks. My M&P 40's are POA/POI. I was disgusted with the 9 and didn't feel it was right for me to drop more money into adjustable sights when it was Smith's problem not mine, so I traded the gun for another 40 at a local gunshop. I refuse to buy another M&P 9 again. A buddy of mine just bought 3 FS M&P 9's and so far he has shot 2 of them. One is dead on, the other is 3" low. He is going through the motions with Smith just as I did. I hope he and the OP have better luck than me.