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Old February 12, 2019, 12:32 PM   #1
TrueBlue711
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357 Sig & 40 in same gun

So I finally got a 357 Sig barrel for my S&W M&P 40. I took it to the range yesterday and shot with both barrels at 5 & 10 yds. At 5 yds, not a huge difference in point of impact. However, at 10 yds, the 357 Sig consistently shot about 4-5" low compared to the 40. Since the gun is originally a 40, I know the sights are meant for that caliber and I figured there would be a difference in POI between the two calibers.

Does anybody else swap between the two calibers in the same pistol know some tips? Do you just keep the POI difference in mind and aim differently with the different barrels? Or do you do something else to account for it?
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Old February 12, 2019, 02:47 PM   #2
74A95
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First, the different POI at the range you're shooting might not be because they are different calibers. That is, bullet drop won't be that different at those distances.

The most likely explanation is that they are 2 different barrels. That is, they are 'pointing' to 2 different locations. Thus you could get different POIs with 2 barrels of the same caliber.
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Old February 12, 2019, 04:34 PM   #3
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The faster 357 SIG will shoot to a lower point of impact than .40 S&W will using the same sights and the same hold (sight picture). That is because the projectile clears the barrel sooner so that recoil has had less opportunity to cause muzzle rise.

The change in POI may depend a bit on barrel length and will vary a bit with different loads producing varying muzzle velocities. The faster projectile will shoot flatter, however, so at some point the POI for the 357 SIG will be higher than that for the slower .40 S&W, but you will probably have to shoot at ranges well beyond 25 yards to see that.

I shoot .40 S&W and 357 SIG out of two different SIG P229 pistols. I shoot a lot more .40 S&W than 357 SIG. One pistol is sighted for what SIG feels is appropriate for .40 S&W and one has sights for 357 SIG. I just adjust hold as necessary.
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Old February 13, 2019, 09:31 AM   #4
TrueBlue711
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Quote:
The faster 357 SIG will shoot to a lower point of impact than .40 S&W will using the same sights and the same hold (sight picture). That is because the projectile clears the barrel sooner so that recoil has had less opportunity to cause muzzle rise.
I got the same logic from others I talked to as well and it makes sense.

Quote:
I just adjust hold as necessary.
I kinda figured this would be the best bet for me. No biggie, just need to shoot more of it to learn the hold zero better.
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Old February 13, 2019, 09:52 AM   #5
riffraff
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Quote:
Originally Posted by pblanc View Post
The faster 357 SIG will shoot to a lower point of impact than .40 S&W will using the same sights and the same hold (sight picture). That is because the projectile clears the barrel sooner so that recoil has had less opportunity to cause muzzle rise.

The change in POI may depend a bit on barrel length and will vary a bit with different loads producing varying muzzle velocities. The faster projectile will shoot flatter, however, so at some point the POI for the 357 SIG will be higher than that for the slower .40 S&W, but you will probably have to shoot at ranges well beyond 25 yards to see that.

I shoot .40 S&W and 357 SIG out of two different SIG P229 pistols. I shoot a lot more .40 S&W than 357 SIG. One pistol is sighted for what SIG feels is appropriate for .40 S&W and one has sights for 357 SIG. I just adjust hold as necessary.
Interestingly I recently noticed the 357 barrels available for my 229 .40, hadn't even googled it yet but sounded interesting. Is that the only part you need to make the switch?
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Old February 13, 2019, 10:11 AM   #6
TrueBlue711
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Quote:
Is that the only part you need to make the switch?
Yup, that's all it takes. I thought it was a cool concept too: two guns in one with a simple barrel swap.
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Old February 13, 2019, 10:30 AM   #7
pblanc
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Yes, the same magazines and recoil spring assembly will work for both .40 S&W and 357 SIG in a P229.

Most SIG P229s chambered in either 9 mm Luger or 357 SIG come with a sight set that has a #8 front and a #8 rear sight and most P229s chambered in .40 S&W come with a #6 front and a #8 rear sight. It is a bit counter-intuitive, but the higher the number on the front sight, the shorter the front sight post whereas the higher the number on the rear sight the higher the height of the sight. So putting a sight with a larger number on either the front, the rear, or both will raise the POI.

Most SIGs including the P229 seem to be set up for a "combat" or "drive the dots" sight picture in which the dot on the front sight post covers the intended POI at ranges from around 12.5-25 yards. I actually prefer the sight picture provided by a #8 front and rear sight combo even when shooting .40 S&W as it places the intended POI at or near the top of the front sight post. So I will usually use my slide with the #8s when shooting either .40 S&W or 357 SIG.

If you think you want a 357 SIG barrel for your P229 I would not wait too long as SIG seems to be phasing out 357 SIG in general. I have heard that the caliber X-change kits for the P22x in 357 SIG are no longer available. Fortunately, if you have a P229 chambered in .40 S&W you don't need the caliber X-change kit, just the barrel. You would need the kit if you wanted to go from 9 mm Luger to 357 SIG.
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Old February 14, 2019, 03:23 PM   #8
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Cool thanks guys - may just grab a barrel and play around with it to see what I think.
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Old February 27, 2019, 12:42 PM   #9
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I have no problems with either barrel in my FS M&P 40. When target shooting I use SPEER TMJ for both calibers. SD, the .357 SIG is 125 gr. PDX1. The .40 is Ranger T-Series 165 gr.
I also have a STORM LAKE 9mm drop in barrel for my 40 as well. SD ammo is Ranger Bonded 147 gr.
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Old February 28, 2019, 12:25 PM   #10
tipoc
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As mentioned, different weight bullets will hit at different spots.

5" at 10 yards is not common though. Likely it's the different reaction of the shooter to the different recoil.

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Old February 28, 2019, 05:12 PM   #11
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Quote:
Originally Posted by tipoc View Post
As mentioned, different weight bullets will hit at different spots.

5" at 10 yards is not common though. Likely it's the different reaction of the shooter to the different recoil.

tipoc
That's what I'm thinking. Let another experienced shooter try it before making any changes.
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Old February 28, 2019, 06:31 PM   #12
pblanc
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I agree that a shift in POI of 5" at 10 yards is much more than would be expected due to the projectile velocity alone.

SIG most often uses a #6 front and #8 rear sight on their P229s chambered in .40 S&W and a #8 front and rear on their 9 mm and 357 SIG P229s. The #8 front sight is shorter so as to raise the POI. SIG claims that a change in front sight height of 1 number will shift POI by 1" at 25 yards and a change in rear sight height of 1 number will shift POI by 2" at 25 yards. So going from a #6 to a #8 front sight with the same rear sight would shift POI by 2" at 25 yards or 1" at 12.5 yards.

That is about inline with my experience with the SIG P229. If one uses the same pistol with the same sights to shoot both .40 S&W and 357 SIG using the same hold, the POI for the faster 357 SIG will be about 1" lower at 10-12.5".

Of course, things might be different with the S&W M&P, but I doubt the shift in POI would be close to 5" at that range.
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Old March 1, 2019, 05:03 AM   #13
silvermane_1
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Quote:
Originally Posted by pblanc View Post
Yes, the same magazines and recoil spring assembly will work for both .40 S&W and 357 SIG in a P229.

Most SIG P229s chambered in either 9 mm Luger or 357 SIG come with a sight set that has a #8 front and a #8 rear sight and most P229s chambered in .40 S&W come with a #6 front and a #8 rear sight. It is a bit counter-intuitive, but the higher the number on the front sight, the shorter the front sight post whereas the higher the number on the rear sight the higher the height of the sight. So putting a sight with a larger number on either the front, the rear, or both will raise the POI.

Most SIGs including the P229 seem to be set up for a "combat" or "drive the dots" sight picture in which the dot on the front sight post covers the intended POI at ranges from around 12.5-25 yards. I actually prefer the sight picture provided by a #8 front and rear sight combo even when shooting .40 S&W as it places the intended POI at or near the top of the front sight post. So I will usually use my slide with the #8s when shooting either .40 S&W or 357 SIG.

If you think you want a 357 SIG barrel for your P229 I would not wait too long as SIG seems to be phasing out 357 SIG in general. I have heard that the caliber X-change kits for the P22x in 357 SIG are no longer available. Fortunately, if you have a P229 chambered in .40 S&W you don't need the caliber X-change kit, just the barrel. You would need the kit if you wanted to go from 9 mm Luger to 357 SIG.
^Thanks for posting this info pblanc.
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