P229 .40S&W Switch to .357 Sig Barrel Shoots Low

[ledavatar]

Does anyone have a handloading solution for a .40 S&W caliber gun switched to .357 Sig w/ a barrel change? I wonder if by varying the charge you can get the POI higher.

[2mike]

Any time you replace a barrel you will have to resight the gun. with the .357 sig which is a hotter round it won't shoot the same as a .40 s&w.

Stay with the .40 it is a better all around round.

[OBIWAN]

Seems likely it is a barrel issue

The .357 sig in most loadings will shoot flatter than .40

When I put my .357 Sig barrel in my G35 it shot perfectly to POA

And it was much more fun than the .40

[highmtn]

I agree with OBIWAN, the .357 sig is a fun round, very flat, very accurate. I have a P229 and I have no issues with accuracy in most shooting situations with barrel change out. Once this gun was originally sighted in...it has always been my go to auto pistol for fun and accuracy. I find that my .357 sig reloads are superior to the .40 rounds that I can produce so far.

[ledavatar]

Hrmm, interesting. I have the siglite night sights on my P229, so I don't know if that has to do with it. I only shot a box of the .357 Sig so far, at an outdoor range when it was really windy, so that might have impacted the results. I will see how my first batch of loaded rounds w/ Power Pistol shoots.

[James A. Mullins]

Hi. Dose your gune have fixed or adjustable? If these are reloads, are you at the starting load or next to max? Hotter loads will shoot higher (heavier loads). If your loads group the way you want, and you have fixed sights, you can carefully file down the frount sight to sight in. Make sure its the load you want to { STICK WITH ] if you change your mind, you will haftto replace the sight.
Best of luck.
James

[ledavatar]

My sights are fixed. I don't want to file it down because they're expensive night sights. I'd rather play around with the loadings if possible. I like heavy loads for the .357 Sig anyway.

[RERICK]

If your loads group the way you want, and you have fixed sights, you can carefully file down the front sight to sight in

.

File the site on my $900.00 Sig no way !


OK while I wrote this I called my gunsmith and he said that when it leaves the factory it gets a rear site at the proper height to shoot .40 caliber. By changing to .357 Sig you will need a different height rear sight.He said to call Sig and either have them do it or get a gunsmith to do it. You could also play around with different weight bullets and powder charges until you get the right combo.

I really think you need to decide which you want to shoot either 40 or 357 and stick with that.I could be mistaken but in my experience a lighter bullet will shoot higher than a heavier one.

[jdmick]

in my experience a lighter bullet will shoot higher than a heavier one

It's usually just the opposite. A lighter bullet travels faster and allows less time for the muzzle to rise so they will hit low. If you're using say a 180g bullet for the .40 S&W and go down to a 125g for the .357 Sig it should hit lower. I would try some heavier bullets for the .357 and see what happens. What weights are you using?

[ledavatar]

yup, I'm was using 180gr .40s and then switched to 125gr .357. I would rather keep the 125gr as my standard load for the .357 just because that's the original intended load. As for .40s, I'm thinking of switching to 165gr or 155gr.

[RERICK]

I got this off Speers web sight.Judge for your self what it says about light and heavy bullets



Effect of Ballistic Coefficient on Bullet Drop and Remaining Velocity


To illustrate, refer to Table 4.2-1(rifle) Table 4.2-1(handgun) which shows remaining velocity and drop data for three hypothetical bullets. The first is a heavy bullet with very good ballistic efficiency so that it has a ballistic coefficient C equal to 0.6. The second is a bullet of medium weight and moderate ballistic efficiency with C equal to 0.4. The third is a light bullet with low ballistic efficiency and C equal to 0.2. Remaining velocity and drop are shown for three muzzle velocities, 3500, 3000, and 2500 fps.

First, let us compare the ballistic performance of these three bullets when all three are fired at the same muzzle velocity, say 3000 fps. Looking at the numbers in Table 4.2-1(rifle) Table 4.2-1(handgun) for the three bullets at the muzzle velocity of 3000 fps, we see that at both 500 and 1000 yd. ranges the bullet with the highest ballistic coefficient ( C = 0.6) retains more velocity and shoots flatter (less drop) than the other two bullets. Similarly, the bullet with C = 0.4 retains more velocity and shoots flatter than the bullet with C = 0.2.

These comparisons can be generalized. If we compare any bullets fired at the same muzzle velocity, the bullet with the highest ballistic coefficient will retain more velocity and shoot flatter than the others at any range. But we know that this type of comparison is not exactly fair. That’s because heavy bullets cannot be loaded to the same muzzle velocities as light bullets. So, we need to consider the muzzle velocity limits of different bullets when we compare their ballistics.

[OBIWAN]

The 125 gr might be the "boutique load" for the .357

But I would go with heavier bullets

[2mike]

You need to change your sights or stay with one caliber or the other.
Because changing bullet size and trying to come up with loads that will make both bullets react close enough to use the same sights would be like comparing apples and oranges. the 357 sig round shoots at a much higher velocity than the 40.