Regulating Shield Sights for 147gr Ammo - MP-Pistol Forum

Regulating Shield Sights for 147gr Ammo

This is a discussion on Regulating Shield Sights for 147gr Ammo within the MP SHIELD Pistols forums, part of the Smith & Wesson MP Forum category; I see that a lot of people like using the 147gr 9mm ammo that is out there, as do I. So I can't be the ...


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Old February 23rd, 2017, 12:17 PM   #1
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Regulating Shield Sights for 147gr Ammo

I see that a lot of people like using the 147gr 9mm ammo that is out there, as do I. So I can't be the only one that has run in to the issue of the POI being higher than the POA (@ 15 yards). Does anyone have a good way to get the POA and the POI to be the same with 147gr ammo? Or does everyone just use a 6 o'clock hold?

For this discussion assume that the front sight is tritium or fiber optic, etc,. and cannot be altered. A taller front sight could be installed, but the existing sight cannot be modified. Thanks for your thoughts.
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Old February 23rd, 2017, 01:24 PM   #2
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The problem might be the 6 o'clock hold. M&P's use a combat sight picture, where you cover the target with the front sight.

M&P Sight Picture

While number 2 will work, I find number 3 to work well for me! Hope this helps!
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Old February 23rd, 2017, 03:16 PM   #3
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Quote:
Originally Posted by Bill in Tx View Post
The problem might be the 6 o'clock hold. M&P's use a combat sight picture, where you cover the target with the front sight.

M&P Sight Picture

While number 2 will work, I find number 3 to work well for me! Hope this helps!
Hi Bill, thank you for the response, under normal circumstances, and standard bullet weights, you are correct about the desired sight picture. Also, with any bullet, a 6 o'clock hold would cause the bullet to hit lower than the other two sight pictures, not higher.

The problem is that the 147gr bullet is in the barrel longer than a 124 or 115gr bullet. The gun starts to lift as soon as the cartridge is fired, so the bullet being in the barrel longer means that the gun has a fraction of a second longer to lift before the bullet exits the barrel, causing a higher POI than a lighter bullet.
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Old February 23rd, 2017, 05:53 PM   #4
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Just how much difference between your POI and POA ?

You can only select one distance where POI = POA.

In your case, when POI is higher than the POA it means your zero is less than 15 yards, rather unusual.

If you can’t alter your front sight, lower your rear sight with a file if you need a 15 yard zero.
Add a laser and adjust the POI exactly as desired.

Seriously, the POI is higher because the weapon is lifting for a fraction of a second longer with a heavier bullet ?
The heavier bullet may or may not have a slower muzzle velocity than a lighter bullet depending on powder / primer load. Muzzle velocity not bullet weight is the primary determinant of ballistic trajectory.

The "problem" is not the bullet weight; control the weapon's muzzle attitude the same regardless of the bullet weight ! and your problem is partially solved.

Make sure you are not limp-wristing during the shot.

The Shield has a 3.1" barrel; as noted in all S&W Owner Manuals, for 3" barrels or less the best you can hope for @ 14 yards is 4" with the gun held in fixture.


Last edited by mp9werks; February 23rd, 2017 at 06:25 PM.
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Old February 23rd, 2017, 06:56 PM   #5
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Quote:
Originally Posted by 4dsjw View Post
I see that a lot of people like using the 147gr 9mm ammo that is out there, as do I. So I can't be the only one that has run in to the issue of the POI being higher than the POA (@ 15 yards). Does anyone have a good way to get the POA and the POI to be the same with 147gr ammo? Or does everyone just use a 6 o'clock hold?

For this discussion assume that the front sight is tritium or fiber optic, etc,. and cannot be altered. A taller front sight could be installed, but the existing sight cannot be modified. Thanks for your thoughts.
Other than going to a 6:00 hold; go to a lighter weight bullet.

You already know the cause; so what's the issue?

I use 115gr bullets in 9mm, and 230gr in .45acp.

That way; everything shoots like it's supposed to.
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Old February 23rd, 2017, 07:51 PM   #6
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Keep in mine 9mm handguns are designed for the standard bullet weight for 9mm for about 100 years, and that's 115 gr, anytime you use ammo outside the standard bullet weight your point of impact will be different, the more difference between the standard and the bullet weight you use, the more difference in the point of impact.

Back when I was a Deputy Sheriff, that was back in the revolver days, most of us carried Model 19 or Model 66, medium frame in blue or nickel or the 66 in stainless, which is what I carried. Standard bullet weight in 38 special or 357 magnum is 158 gr. A new ammo came out called Hi-Vel, a variation of the term High Velocity, which was achieved by using a light weight bullet, 125 gr. The 125 gr quickly achieved the notoriety of being the #1 bullet for 1 shot stop, so everybody wanted to carry it.

Well, there were a few problems, the muzzle blast approached Hiroshima, it produced so much flash there was a problem with flame cutting on the frame of the mid frame Smiths like the Mod 19 and 66, and that other elephant in the room, wait a minute, I shot at that target...where are my hits? Down there in the dirt somewhere! It shot so low I couldn't adjust my sights enough to compensate, at 25 yards with the adjustable sights as far as they would go, it was still shooting about a foot low! Even though I could order special sights to help compensate, the natural point and shoot was all fouled up, the gun no longer shot where you pointed it when you didn't use the sights. Light bullets shoot low, heavy bullets shoot high, its all connected to recoil. 125 gr bullets were so messed up on point of aim I went back to 158 grain.
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Old February 24th, 2017, 02:01 AM   #7
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Don't know if this will help but I load my Shields with Federal HST. My 9mm with 147 and my 45 with 230 grain. Both are used for conceal carry so when I'm at the range I'm practicing with the target between 5 to 10 yards and I'm putting the front sight and hitting my double and triple taps center mass. So I quess the short answer is I'm covering my impact point with the front sight.

Last edited by usmc1963; February 24th, 2017 at 11:48 AM.
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Old February 24th, 2017, 08:41 AM   #8
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Quote:
Originally Posted by mp9werks View Post
Just how much difference between your POI and POA ?

Seriously, the POI is higher because the weapon is lifting for a fraction of a second longer with a heavier bullet ?

The heavier bullet may or may not have a slower muzzle velocity than a lighter bullet depending on powder / primer load. Muzzle velocity not bullet weight is the primary determinant of ballistic trajectory.

The "problem" is not the bullet weight; control the weapon's muzzle attitude the same regardless of the bullet weight ! and your problem is partially solved.

Make sure you are not limp-wristing during the shot.

The Shield has a 3.1" barrel; as noted in all S&W Owner Manuals, for 3" barrels or less the best you can hope for @ 14 yards is 4" with the gun held in fixture.
- the difference between POA and POI is about 3"-4".
- at 15 yards the bullet trajectory is going to have a marginal effect.
- heavier bullets are generally driven at slower velocities and DO exit the barrel later, impacting higher at any given distance.
- the muzzle attitude is being controlled the same way every time. I have a well defined 4"-5" group @ 15 yards that is hitting 3"-4" above POA.
- I don't limp-wrist and do not have this POA/POI issue with any of the other handguns I have.
- Thank you for the S&W graphic, very useful to have.


Quote:
Originally Posted by Rick M View Post
Other than going to a 6:00 hold; go to a lighter weight bullet.

You already know the cause; so what's the issue?

I use 115gr bullets in 9mm, and 230gr in .45acp.

That way; everything shoots like it's supposed to.
Hmmm, I use 147gr HST's for SD ammo so I use 147gr target ammo. The idea that I should shoot ammo that works with the sights, instead of regulate the sights to work with the ammo that I want to use, is... well... not the best choice imo. If that works for you that's good. Like you, I also use 230gr ammo in my M&P45, and it hits dead on with a center hold sight picture.



Quote:
Originally Posted by G56 View Post
Keep in mine 9mm handguns are designed for the standard bullet weight for 9mm for about 100 years, and that's 115 gr, anytime you use ammo outside the standard bullet weight your point of impact will be different, the more difference between the standard and the bullet weight you use, the more difference in the point of impact.

Light bullets shoot low, heavy bullets shoot high, its all connected to recoil. 125 gr bullets were so messed up on point of aim I went back to 158 grain.
G56, thank you for sharing your knowledge and practical experience with the use of heavier and lighter bullets.

Last edited by 4dsjw; February 24th, 2017 at 09:42 AM.
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Old February 26th, 2017, 03:58 PM   #9
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Quote:
Originally Posted by 4dsjw View Post
Hi Bill, thank you for the response, under normal circumstances, and standard bullet weights, you are correct about the desired sight picture. Also, with any bullet, a 6 o'clock hold would cause the bullet to hit lower than the other two sight pictures, not higher.

The problem is that the 147gr bullet is in the barrel longer than a 124 or 115gr bullet. The gun starts to lift as soon as the cartridge is fired, so the bullet being in the barrel longer means that the gun has a fraction of a second longer to lift before the bullet exits the barrel, causing a higher POI than a lighter bullet.
I apologize if I misunderstood the question. I thought you were saying that you were using a 6 o'clock hold.
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Old February 26th, 2017, 04:13 PM   #10
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I apologize if I misunderstood the question. I thought you were saying that you were using a 6 o'clock hold.
Hi Bill, no worries. When I put up a post I appreciate any and all responses that I get. The replies that offer up different ideas than my own always make me think through the issue one more time, so it's all good.

I was hoping that someone had already done some homework and found replacement front or rear sights that would work with the 147gr loads. Since this Shield will most likely always use 147gr ammo I will probably get a replacement rear sight that has a serrated surface with no dots, shorten the top surface the correct amount, then modify the opening/notch to my taste.
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Old February 26th, 2017, 06:55 PM   #11
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Quote:
Originally Posted by 4dsjw View Post
- the difference between POA and POI is about 3"-4".
- at 15 yards the bullet trajectory is going to have a marginal effect.
- heavier bullets are generally driven at slower velocities and DO exit the barrel later, impacting higher at any given distance.
- the muzzle attitude is being controlled the same way every time. I have a well defined 4"-5" group @ 15 yards that is hitting 3"-4" above POA.
- I don't limp-wrist and do not have this POA/POI issue with any of the other handguns I have.
- Thank you for the S&W graphic, very useful to have.




Hmmm, I use 147gr HST's for SD ammo so I use 147gr target ammo. The idea that I should shoot ammo that works with the sights, instead of regulate the sights to work with the ammo that I want to use, is... well... not the best choice imo. If that works for you that's good. Like you, I also use 230gr ammo in my M&P45, and it hits dead on with a center hold sight picture.

But you started out saying you couldn't regulate the sights because of "dot or tritium front sight" or some such.





G56, thank you for sharing your knowledge and practical experience with the use of heavier and lighter bullets.
See response within quote.

If you won't change the sights to match your load, you have to either match your load to the sights, apply "Kentucky windage," or learn not to use the sights (threat focused shooting).

It makes no difference to me what you do; but you started the thread identifying what your "problem" was.

How you deal with it is up to you.

Last edited by Rick M; February 26th, 2017 at 07:01 PM.
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Old February 27th, 2017, 04:29 PM   #12
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Quote:
Originally Posted by Rick M View Post
See response within quote.

If you won't change the sights to match your load, you have to either match your load to the sights, apply "Kentucky windage," or learn not to use the sights (threat focused shooting).

It makes no difference to me what you do; but you started the thread identifying what your "problem" was.

How you deal with it is up to you.
Rick, appreciate that it doesn't matter to you, thank you for sharing. The thread topic is, "Regulating Shield Sights for 147gr Ammo" and that is what I'm hoping to do, change the sights. The one caveat was that the existing front sight "... cannot be altered. A taller front sight could be installed, but the existing sight cannot be modified. My apologies if my choice of words did not make it clear.

That would leave, modifying the rear sight, replacing the rear sight (with an appropriate height version), replacing the front sight (with an appropriate height version), or some combination of the above. I was hoping that other people who read this Shield specific forum had already embarked on this task and might have some suggestions as to what they had done and what had worked for them.
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Old February 27th, 2017, 06:45 PM   #13
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Originally Posted by 4dsjw View Post
Rick, appreciate that it doesn't matter to you, thank you for sharing. The thread topic is, "Regulating Shield Sights for 147gr Ammo" and that is what I'm hoping to do, change the sights. The one caveat was that the existing front sight "... cannot be altered. A taller front sight could be installed, but the existing sight cannot be modified. My apologies if my choice of words did not make it clear.

That would leave, modifying the rear sight, replacing the rear sight (with an appropriate height version), replacing the front sight (with an appropriate height version), or some combination of the above. I was hoping that other people who read this Shield specific forum had already embarked on this task and might have some suggestions as to what they had done and what had worked for them.
Oh; got it now.

I did misunderstand your comment about the front sight in your OP.

There is a formula that will identify how much of a change one needs to make in sight height to move the POI based on the distance between the front and rear sight (sight radius) and the distance to the target.

I'll try to find it, but the amount of change is relatively small.

Edit: Here's a link to an online calculator that you can use on Brownell's website:

http://www.brownells.com/GunTech/Sig....htm?lid=13093

Last edited by Rick M; February 27th, 2017 at 06:50 PM.
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Old February 28th, 2017, 01:21 PM   #14
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Verify how much you would like the POI changed. Go to Dawson Precision and look up the calculator for front sight change. Measure the existing sight (from top of slide), use the correction factor from the formula and order a sight taller than the origonal. _or_ Go to a good gunsmith and have him change the front sight. Either way you must know how much the POI needs to be changed
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Old March 29th, 2017, 04:24 PM   #15
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Just checking back in with some, hopefully useful, info for others that may be having the same issue. Did some careful measuring at the range today, then checked the Brownell's and Dawson websites. Both agreed that I need to raise the front sight, or lower the rear sight, by .043 inches, to bring my POI down to my POA, at 15 yards, using 147g ammo in my Shield9. I will machine the rear sight down and file the notch to my liking.

Thank you for all the useful comments, suggestions, and links.

One caveat: if you are having the same issue you should carefully measure the discrepancy between the POA and the POI for your gun. All guns are different and the correction for your gun may not be the same as the correction for my gun.
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