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helpme
10-06-2011, 4:14 PM
I might be replacing the sights on my Kimber in the near future and I want a set of fixed sights that will have the "Point of Impact" exactly aligned with the "Point of Aim". What are my best options in order to achieve that goal?

redcliff
10-06-2011, 5:58 PM
A Bomar copy (they're out of business now) buried deep in your slide, or a Novak adjustable comes to mind.

With fixed sights you're going to have poi/poa exactly coincide only at two distances; once on the bullets way up to intersect your line of sight and once on its way down after it's trajectory peaks.

tacticalcity
10-08-2011, 1:55 AM
Your sight came with the upgraded meprolight sights and it is still not poa/poi? Something sounds fishy to me. Are you 100% sure its not the shooter? It is human nature to blame the equipment but almost always the wrong diagnosis. Usually it's the part pulling the trigger that is faulty...a rule of thumb I apply to myself as well.

While my Ameriglo sights are made by Triijicon, they are virtually identical to the Tactical Wedges that come with Kimbers. They are poa/poi at 15 yards with the 230gr ball ammo I've used (give or take less than 1/4 an inch).

melensdad
10-08-2011, 7:23 AM
Define your distance.

Define your bullet weight.

Define your bullet velocity.

"Point of Aim" and "Point of Impact" only meet at one single defined distance along the sight plane of the "point of aim."

Change your bullet weight and that PoA relative to the PoI will be different. Use the same bullet weight but change the velocity (switch to subsonic ammo, for example) and the PoA relative to the PoI will again be different. Change both the bullet weight and the bullet velocity and again you will have a different PoA to PoI relationship.

The first reason this is true is because your sights are above your bore axis. The higher your sights above the bore axis the more differential you will notice in the relationship to PoA and PoI. The second reason this is true can be blamed on an apple and a man named Sir Issac Newton. Bullets drop. From the moment the bullet leaves the end of the barrel it is actually falling toward earth. Combine those two, with the above factors of bullet velocity and you will have to determine the single point along the sight plane where your PoA and PoI are an exact match given your specific ammo choice.

In more simplistic terms, if this is a gun for self defense inside your home and the longest shot you will take inside you home is about 18 feet (roughly 6 yards) then you probably don't want to set your sights to align the PoA and PoI at the 25 yard lane at your local shooting club. And you certainly don't want to do it with 230 grain surplus ball ammo if your self defense ammo is a +P rated high velocity 185 grain round.

redcliff
10-08-2011, 9:07 AM
Define your distance.

Define your bullet weight.

Define your bullet velocity.

"Point of Aim" and "Point of Impact" only meet at one single defined distance along the sight plane of the "point of aim."

Change your bullet weight and that PoA relative to the PoI will be different. Use the same bullet weight but change the velocity (switch to subsonic ammo, for example) and the PoA relative to the PoI will again be different. Change both the bullet weight and the bullet velocity and again you will have a different PoA to PoI relationship.

The first reason this is true is because your sights are above your bore axis. The higher your sights above the bore axis the more differential you will notice in the relationship to PoA and PoI. The second reason this is true can be blamed on an apple and a man named Sir Issac Newton. Bullets drop. From the moment the bullet leaves the end of the barrel it is actually falling toward earth. Combine those two, with the above factors of bullet velocity and you will have to determine the single point along the sight plane where your PoA and PoI are an exact match given your specific ammo choice.

In more simplistic terms, if this is a gun for self defense inside your home and the longest shot you will take inside you home is about 18 feet (roughly 6 yards) then you probably don't want to set your sights to align the PoA and PoI at the 25 yard lane at your local shooting club. And you certainly don't want to do it with 230 grain surplus ball ammo if your self defense ammo is a +P rated high velocity 185 grain round.

We'll have to agree to disagree on this point of Point of Aim only meeting at one Point of Impact.

As you can see from the chart below (its for a rifle but the concept is the same for pistols), due to the sights being above the boreline the barrel is actually angled upwards on its line of departure to meet our line of sight; therefore the trajectory passes through line of sight twice.
http://i287.photobucket.com/albums/ll137/ranjaz/rsballistics_0303a.jpg

eaglemike
10-08-2011, 9:23 AM
Agree with the above.

You can also change your load (using some of the principles noted above.)

Ex: your gun is shooting above POA with a 230gr load at 750fps. Try a 185 gr load at 1000fps. Use the same hold and POA. You might be surprised at the difference.

melensdad
10-08-2011, 11:18 AM
We'll have to agree to disagree on this point of Point of Aim only meeting at one Point of Impact.
If we were talking about a rifle I would concede the point. Your chart shows 200 yard with 2 intersection points. DO YOU HONESTLY WANT TO DISCUSS 200 YARD SHOTS WITH A SELF DEFENSE HANDGUN? :facepalm:

My point stands as valid at ALL HANDGUN self defense shooting distances. There will NEVER be 2 intersecting points along the line of sight (PoA) at ANY HANGUN self defense shooting distance. NOT EVER.

If you REALLY want to get into the technical aspects of this then we need to get out of this thread because your post is about as relevant to the OP as a sun dried tomato is to a thirsty penguin.

Honestly I have no problem discussing this further with you, but for the sake of the OP why don't we try to stay relevant to the topic?



.

redcliff
10-08-2011, 11:27 AM
If we were talking about a rifle I would concede the point. Your chart shows 200 yard with 2 intersection points. DO YOU HONESTLY WANT TO DISCUSS 200 YARD SHOTS WITH A SELF DEFENSE HANDGUN? :facepalm:

My point stands as valid at ALL HANDGUN self defense shooting distances.

If you REALLY want to get into the technical aspects of this then we need to get out of this thread because your post is about as relevant to the OP as a sun dried tomato is to a thirsty penguin. Honestly I have no problem discussing this, but for the sake of the OP why don't we try to stay relevant to the topic?

I'm sorry, but the effect is the same for a handgun as it is for a rifle, and I clearly stated the chart was for a rifle, I didn't have one for a handgun available. I'm sorry the concept is eluding you but using CAPS, different text colors and making disparaging remarks about thread relevance doesn't change the fact that you are simply wrong. Heres some ballistics for you if that helps:

Assuming a 25 yard zero on your 1911.
For 230 grain JRN the trajectory will be about like this:
10 yards -0.07"
15 yards +0.08"
25 yards 0
35 yards -0.61"

POA=POI at around 12 yards also. Therefore the bullet trajectory coincides with point of aim at two distances at relevant handgun distances.

melensdad
10-08-2011, 11:45 AM
I'm sorry, but the effect is the same for a handgun as it is for a rifle, and I clearly stated the chart was for a rifle, I didn't have one for a handgun available. I'm sorry the concept is eluding you but using CAPS, different text colors and making disparaging remarks about thread relevance doesn't change the fact that you are simply wrong. Heres some ballistics for you if that helps:

Assuming a 25 yard zero on your 1911.
For 230 grain JRN the trajectory will be about like this:
10 yards -0.07"
15 yards +0.08"
25 yards 0
35 yards -0.61"

POA=POI at around 12 yards also. Therefore the bullet trajectory coincides with point of aim at two distances at relevant handgun distances.

First off, why the heck would you want a 25 yard 'zero' on a self defense handgun?

Can you honestly swear in court that someone 75' away was a serious threat to you?

As I stated, technically the handgun will work the same as the rifle, bullet drop, point of aim, blah blah blah. I pointed all that out. But in the PRACTICAL world of self-defense shootings there is no way your point is defendable.

Take a typical room, say it is 12' wide by 18' long. Bad guy is in the room threatening you. He is 3' from the far wall, his body is 18" thick. You are 3' from the opposite wall, your body is 18" thick and you have arms that extend out another 36". So in that 18' long room the muzzle of your gun is about 7 FEET from the chest of your attacker.

Why the heck are you talking YARDS when most relevant data suggests INCHES to FEET are the actual distances at which we need to consider point of impact???

The laser on my home defense handgun is set to point of impact a 12'. Honestly I think that is too far, but I live in an open plan type house with some remotely possible slightly longer than normal shooting distances.

It would be fun to sit on your jury.

redcliff
10-08-2011, 12:24 PM
"Point of Aim" and "Point of Impact" only meet at one single defined distance along the sight plane of the "point of aim."



I only reposted on this thread because of the above false statement you made calling my original post into question and your dissertation on Sir Isaac Newton as if I had never heard of him.

Feel free to keep changing your argument, it's ok. I know some people can't admit when they're wrong.

I hope you have a nice day.

sevensix2x51
10-08-2011, 12:39 PM
I may have missed something, but I do not recall the OP asking about self defense.

sevensix2x51
10-08-2011, 3:02 PM
Well, I just measured the front Meprolight sight on my Kimber Pro-Carry, and it has a .180 front sight height. Looking at Meprolight's offerings, your front sight is -probably- the same one (assuming, of course, that you have a standard kimber Meprolight front blade on your pistol), because they only seem to offer that height, and then some really tall ones for the target-style sights.

Brownells description says that the sight in your link regulates with a .225" front blade, so it sounds to me, your unofficial internet opinion text box guy, that you may very well be hitting just as high with the new rear sight you are looking at, unless it has a lot of downward adjustment. You might entertain the idea of a new front sight, and while Meprolight does not offer the one that it sounds like you need, Novak makes a Tritium one that is .215" and much closer to the .225" needed to regulate with those Novak rear sights. It sounds like the front dovetail may need to be modified slightly to accept this blade, but I am not sure..

I would first buy the taller blade to push your POI down, then if it is still a problem, then your new front blade is much closer to spec for the new Novaks you are looking at.

I hope that makes sense, I just had a Mountain Dew, so I might be rambling. Just trying to help. :)

redcliff
10-08-2011, 5:33 PM
CAN ANYONE ANSWER MY QUESTION?

Would these rear sights (http://www.brownells.com/.aspx/sid=41894/pid=41869/Sight+Color_1054=Tritium/Product/Rear-Sights--TR-fits-Colt?utm_medium=shoppingengine&utm_source=googlebase&mc_id=10000&gdftrk=gdfV21820_a_7c187_a_7c3466_a_7c625000011_d_ 100001521_d_10586#skugrid) be compatible with my Meprolight Tactical Wedge front sight on my Kimber Custom II?

As sevensix2x51 noted,reading the description it says you need a .225 tall front sight. How tall is your existing sight? You're aware that the rear sight you're looking at will require miling of the slide in front of the rear dovetail correct?

If you shoot a target at the distance you want to be zero'd at and measure how far off target you are in inches, what the distance your target was at and what your current sight radius is in inches, we can tell you how much taller your front sight needs to be to work properly with your existing rear sight if desired.

Gryff
10-08-2011, 5:40 PM
My preference would be a Heinie Ledge rear sight with some form of front post that has a gold bead in it. But it's hard to tell you what is right for you. Remember that not everyone's POA/POI is the same (even with identical sights). You need to find the one that works best for you and hits to POA with the ammo that you are using.

stevie
10-08-2011, 5:51 PM
Go buy a matched set of 10-8's. You will not need to worry about the front or rear height..

http://www.10-8performance.com/categories/Sights/