Front sight height and it's effect on POI at 10 yards, with a CZ 75B.

[Ciph3r]

So I did some calculations on how low or high a round would be if one left the rear sight alone on a CZ pistol and changed the front sight height. I used the Dawson Precision sight calculator backwards with a little extra thinking.

What I've discovered so far:

A 5.5MM (0.216535") tall front sight is what comes on I believe EVERY factory new CZ 75B it should shoot POI at 10 yards.

A 6.5MM (0.255906) tall front sight is 1MM taller, and with the factory rear sight, SHOULD hit exactly 2.39 inches low at 10 yards.

How did I calculate this?

I entered sight distance (6") for a CZ 75B with standard rear sight.

I entered the desired front sight height (5.5MM converted to inches, 6.5MM in inches, and so on.)

I then entered the distance at 10 yards (Absolutely certain my CZ shoots dead on at 10 yards with Federal RTP.)

Changed the point of impact switch to "LOW"

Then from Zero, started changing impact distance from center until the calculator told me the sight I should buy to fix it was the measurement of the standard front sight (5.5MM, .216")

You can flip the switch for lower front sights (5MM, 4.5, ETC) and do the same thing in reverse.

Here are my results:

TEST ROUND: 115 Grain (FEDERAL RTP)

5.0MM (0.196), 10 yards (360"): 1.17" HIGH POI

5.5MM (0.216"), 10 yards (360"): 0.0 POI = POA (Dead on)

6.0MM (0.236), 10 yards (360"): 1.19" LOW POI

6.5MM (0.255), 10 yards (360"): 2.39" LOW POI

7.0MM (0.275), 10 yards (360"): 3.6" LOW POI

7.5MM (0.295), 10 yards (360"): 4.78" LOW POI

This info should be roughly accurate. Someone could chime in on whether or not it is or isn't.

What does this mean?

If I have done this right, this means for every half millimeter you add to the front sight, it translates to roughly 1.19" of POI shift.

How should I use this?

Take it with a grain of salt, but it should help people trying to fix low or high POI, especially on Israeli surplus CZ 75s which are known to be sighted in for extremely high pressure rounds and may shoot extremely low with standard loads.
Shoot a test group, measure your POI's distance from POA, then remove your front sight, measure it, and compare to this chart.

[1SOW]

I haven't checked it but sounds right.
I use 25 yrds for tests and can convert back to 10 yrds by using 10/25th of the 25 yard variation assuming a fairly straight flight path to 25 yards.

My B has a Comp. Rear so mine is 9 9/16" between sights.

[Ciph3r]

I haven't checked it but sounds right.
I use 25 yrds for tests and can convert back to 10 yrds by using 10/25th of the 25 yard variation assuming a fairly straight flight path to 25 yards.

My B has a Comp. Rear so mine is 9 9/16" between sights.

I just used 10 yards because that's where I know that my pistol is shooting spot on. It's easier to start with a dead-on POI than two inches low at 20 yards (Which my standard sight is.)

[1SOW]

So your loads drop 2# in +10 yards??

[Ciph3r]

So your loads drop 2# in +10 yards??

I believe so, yes. I should go and measure it to be sure. Federal RTP is pretty weak stuff, and I found myself missing under a target at 20 yards during a steel competition.