Pistol shooting 1" to 1 1/2 inch low. (Grant or Anyone, Help please)

**RogerinTPA** · 07-29-09, 08:10

I have two M&P pistols with identical sights (straight eights). The M&P9c is dead on. The full size M&P9 is shooting an inch, to an inch an a half low from POA. To compensate, I have to hold high, or displace the front sight by an 1/8 of an inch higher than the rear, in order to hit where I aim. I thought about having the FS shaved down and took it to a "smith" but he said there was too little material on the bottom to adjust. I called the manufacture, explained the situation and asked if they had a different size front sight for me to purchase. They said no, it's the only sight they offer. I saw some alternative sights at brownells, but I don't know the height/size measurement of my current front sight (#409 M&P Ledge Quick), to make an educated decision. Most folks say it's not a big deal, but it is frustrating to pick up any one of my handguns and know I can hit what I'm aiming at, then have to use a modified sight picture on this one. Anyone else with a similar problem using these sights? Thanks.

Roger

**Robb Jensen** · 07-29-09, 08:34

Faster pistol rounds hit lower. You can change to slower ammo to make up for this or go with a shorter front sight.

I had custom fronts made for my M&P9L and M&P Pro because of this.
Kenny at Speed Shooter Specialties can make them for you.
My Pro has a .188" tall by .115" wide serrated front made from a Dawson blank. This works very well for me with 115gr FMJ and 147gr JHP subsonic match ammo.

**Wayne Dobbs** · 07-29-09, 09:43

To determine what kind of sight correction you need use this formula:

Amount of impact error in inches multiplied by sight radius in inches divided by the range at which the group was fired in INCHES.

You don't mention what your range is, but if you multply 1.5 (error) X 6.5 (approximate sight radius) = 9.75 inches divided by 900 (25 yards) = .01 inches of correction needed.

Lots of folks, including gunsmiths will guesstimate this, but the formula has always worked for me.

**TriumphRat675** · 07-29-09, 12:40

I thought my M&P 40 had gone TU when it went from dead on to shooting 1 inch low. I figured out the change was because I was using a few boxes of Speer Lawman practice ammo. When i changed back to wallyworld white box it went back to being dead on. Try a different brand of ammo and see what happens.

**Surf** · 07-29-09, 14:29

As mentioned ammo can make a difference, but at what distance are we talking here?

**RogerinTPA** · 07-29-09, 21:18

Very interesting responses. I never knew faster ammo would shoot low. Learn something new every day, but why is the 9c dead on? Shorter sight radius than the full sized? Thanks for the info gentlemen.

**Robb Jensen** · 07-29-09, 21:26

Originally Posted by rharris2163

Very interesting responses. I never knew faster ammo would shoot low. Learn something new every day, but why is the 9c dead on? Shorter sight radius than the full sized? Thanks for the info gentlemen.

The ammo is going slower out of the smaller gun.

ToddG · 07-29-09, 21:28

Originally Posted by rharris2163

I never knew faster ammo would shoot low

The bullet leaves the barrel sooner, meaning it leaves the barrel earlier in the upward recoil arc.
For tilt-barrel weapons, higher pressure ammo means the barrel takes longer to unlock (begin tilting). Unlocking too early can result in shots going high.