S&W 617 front sight problem

Hakaman · Post by **Hakaman** » Thu Mar 15, 2012 4:47 pm

Since I have had my S&W 617 I have always shot considerably high, even with the adjustable rear sight bottomed
out downward. Although I am far from the best shot in the world, I do think I can tell if it's the gun, or me.
I also have been dissatisfied with the sight picture the black blade offers, so I looked for a replacement. First thing
I tried was super gluing a HiViz fiber optic insert to the top of blade, trying to kill two birds with one stone, higer sight
means lower impact, and the visibility of the fiber optic. As you can see from the pictures below, I had trouble I had
making it look good. So I ordered a couple new sights, 1) a direct replacement, just to have one, and 2) a HiViz fiber optic sight.
I presently have the HiViz front sight mounted and like how it looks while aiming the gun. The strange part about
all this is the direct replacement blade sight, it is much taller then the original. Here's how they measure from
base to top (visible part of sight):
1) Original blade sight = .180"
2) Direct replacement = .275"
3) HiViz Fiber Optic = .275"
Geez, no wonder I was shooting high, they must have installed the WRONG front sight, from the factory !
Here are some pictures of the front sights:

Post by **Bullseye** » Fri Mar 16, 2012 6:48 am

The only thing I can think of is; what distance do you normally shoot your 617? The shorter front sight may mean the factory test fires at a longer range than you, that shorter sight post would compensate for bullet drop out to the target.

R,
Bullseye

blue68f100 · Post by **blue68f100** » Fri Mar 16, 2012 8:42 am

A bullet weight impacts POI too. A heavier bullet will hit higher than a litter one. The front sight you put together looks good.

Hakaman · Post by **Hakaman** » Sat Mar 17, 2012 10:50 am

Most of my shooting is done at 30 feet, but go out to 50 yards at the outdoor
range. At those distances, is there much variance in poa ? I tried out my new
taller HiViz yesterday and, at 30 feet, I had to adjust my rear sight the opposite
extreme, all the way up to get the bullet high enough.
Haka

Post by **Bullseye** » Sat Mar 17, 2012 11:50 am

There can be a big difference in POI between 10 yards and 50 yards, depending on where your revolver is sighted in and the velocity of the rounds. You're on the upward arc for 10 and dropping off at 50.

R,
Bullseye

Hakaman · Post by **Hakaman** » Sat Mar 17, 2012 1:08 pm

You're on the upward arc for 10 and dropping off at 50.

Interesting point here. I was sighting in my AR-15 this past weekend after installing a scope for some fun shooting. I started at the 25yd range to get it close, then moved to the 100yd range. The range officer told me to sight it in one inch "low" on the 25yd range, this should get it close on the 100yd range. It sounds counter-intuitive, but the bullet is actually on an upward trajectory for a certain distance (here, at least 100yds) before it starts to fall. So sighting in below the bullseye at 25 yards is appropriate. I'm sure this is the same for 22lr.
Haka

Post by **Bullseye** » Sat Mar 17, 2012 3:40 pm

Yes, remember the front sight is above the bore and that means the bullet must travel upward to meet up with the "line of sight" aiming point. For the AR we use the 1000" target, which is close to 25 yards to set a battle zero for 200 yards. Plus the AR front sight is far higher off of the bore than your revolver.

R,
Bullseye

Georgezilla · Post by **Georgezilla** » Sat Mar 17, 2012 4:04 pm

Haka, this link has some graphics that illustrate what Bullseye noted:

http://www.dawsonprecision.com/Category ... GHTS+FRONT

One neat thing about bullet trajectories is that firearms can usually be zeroed for 2 distances, one at the +slope and one at -slope. This actually occurs for most .22lr pistols at 25yards and 50yards. If you only shoot your .22 pistol at 25 and 50 yards, your pistol will actually be POI zeroed at both distances with the same elevation settings (saves the bullseye shooters out there a lot of time).

Hakaman · Post by **Hakaman** » Sat Mar 17, 2012 4:57 pm

Haka, this link has some graphics that illustrate what Bullseye noted:

Great site (no pun intended), very informative.
thanks,
haka

charlesb · Post by **charlesb** » Wed Mar 21, 2012 1:28 pm

I have a Nikon scope on my .17HMR rifle that has the little "bullet drop" ovals below the cross-hairs.

The way mine is set up, the cross-hairs are right on, at 100yds.

The first oval below the cross-hairs is used for close-in shots at 25 yards or less - and for @150 yrds or so.

In part, it has something to do with the height of the scope above the bore in addition to the trajectory.