[Beefstews]

So I started with a P320c in .357 SIG and I picked up a .40 barrel for it. If I decide to stay with the .40 barrel, I need to change the sights, correct? My current sights are both #8s. If I stay with .40, I believe I would need to go with a #6 front sight and #8 rear. Please let me know if I am on the right track. Thanks, as always, for any input!

 

[Malicious Compliance]

My suggestion would be to follow the instructions of SIG when adjusting sights. Shoot the gun from a bench rest at 25 yards to determine what the Point of Aim/Point of Impact (POA/POI) actually is for each barrel. You really need to know where you currently are before you can determine where you need to go. Once you know where each barrel is, you can make the appropriate adjustment. I have several SIG's with 9mm/40 S&W/357 SIG barrels and don't find a need to change sights, but I'm not a target/competition shooter.

 

[stlmia]

If I were you, I would shoot it before I changed the sights. I keep seeing people post about the 320 9mm shooting low with the #6 front and #8 rear sight combo. My P250C 40SW has a #8 front and it shoots great for me.

Also, according to SIG's site, the 9mm and the 357 SIG share the same sight combo while the 40SW and 45 share a different sight combo. My P320C 9mm came stock with #6 front and #8 rear.

 

[Beefstews]

You really need to know where you currently are before you can determine where you need to go. Once you know where each barrel is, you can make the appropriate adjustment. I have several SIG's with 9mm/40 S&W/357 SIG barrels and don't find a need to change sights, but I'm not a target/competition shooter.

Yup - I have shot both barrels at 15 yards. I noticed that the .40 barrel hit the target higher than the .357 barrel. Maybe, I am just overthinking and should keep it as is. I think I can just learn to adjust my POA when using the .40

Thank you for the insight!

 

[Beefstews]

My P320C 9mm came stock with #6 front and #8 rear.

Weird...I have a P320F and a P320c both in 9mm and they both came with #8 front and rear sights. Maybe they saw that a #6 was needed for your pistol when they test fired it?

 

[stlmia]

Maybe they saw that a #6 was needed for your pistol when they test fired it?

Yea maybe. More pessimistically, maybe they just threw on whatever they had lying around. Either way, all of mine shoot fine. But I typically only take one or two to the range, so maybe I've just learned to adjust. I'll have to focus more on comparing next time.

Mine came stock as follows (all 9mm):

320c - #6 front and #8 rear.
320fs - TFO front (not sure which) and #8 rear.

250c - #6 front and (not sure which rear)
250fs - #8 front and #8 rear

 

[sigsrok]

Yes, change sights.

The 357 SIG and the .40 have different trajectories. At close range, not much difference.

 

[BikerScout]

I don't know if this helps. Sig Sold a 250C-40 that came with a .357 sig barrel. Used the same sights.

 

[gundrted]

You don't have to change the sights. The difference is so small any normal person is not going to notice. At 5-7 yards there will be almost no difference. Sure at 25 yards there may be a little difference, but does that matter.

I use all 9mm, 357sig and 40sw in Compact/Carry. I Sub-Compact I have 40sw and 9mm. Both my slides came with 40sw barrels and 8/6 sights. I can swap to any barrel and not notice any difference.

 

[gundrted]

https://www.federalpremium.com/ballistics_calculator/

BALLISTICS CALCULATOR

Load Number: WM5199 Zero Range: 7 yd
Caliber: 9mm Luger (9x19mm Parabellum) Temperature: 59 °F
Bullet Style: Full Metal Jacket Wind Speed: 0 mph
Bullet Weight: 115 gr Altitude: 0 feet
Ballistic Coefficient: 0.12 Max Range: 25 yd
Muzzle Velocity: 1180 fps Test Barrel: 4 in
Sight Height: 0.5 in


Range (yd) Drop (in) Wind Drift (in) Velocity (fps) Energy (ft-lb)
0 -0.5 0.0 1180 356
1 -0.4 0.0 1177 354
2 -0.3 0.0 1173 352
3 -0.3 0.0 1170 350
4 -0.2 0.0 1167 348
5 -0.1 0.0 1164 346
6 -0.1 0.0 1161 344
7 0.0 0.0 1158 342
8 0.1 0.0 1154 340
9 0.1 0.0 1151 338
10 0.2 0.0 1148 337
11 0.2 0.0 1145 335
12 0.3 0.0 1142 333
13 0.3 0.0 1139 331
14 0.4 0.0 1136 330
15 0.4 0.0 1134 328
16 0.5 0.0 1131 326
17 0.5 0.0 1128 325
18 0.5 0.0 1125 323
19 0.6 0.0 1122 322
20 0.6 0.0 1119 320
21 0.6 0.0 1117 318
22 0.6 0.0 1114 317
23 0.7 0.0 1111 315
24 0.7 0.0 1109 314
25 0.7 0.0 1106 312

 

[gundrted]

BALLISTICS CALCULATOR

Load Number: AE40R3 Zero Range: 7 yd
Caliber: 40 S&W Temperature: 59 °F
Bullet Style: Full Metal Jacket Wind Speed: 0 mph
Bullet Weight: 165 gr Altitude: 0 feet
Ballistic Coefficient: 0.15 Max Range: 25 yd
Muzzle Velocity: 1130 fps Test Barrel: 4 in
Sight Height: 0.5 in


Range (yd) Drop (in) Wind Drift (in) Velocity (fps) Energy (ft-lb)
0 -0.5 0.0 1130 468
1 -0.4 0.0 1128 466
2 -0.3 0.0 1126 464
3 -0.3 0.0 1123 462
4 -0.2 0.0 1121 460
5 -0.1 0.0 1119 459
6 -0.1 0.0 1117 457
7 0.0 0.0 1114 455
8 0.1 0.0 1112 453
9 0.1 0.0 1110 452
10 0.2 0.0 1108 450
11 0.2 0.0 1106 448
12 0.3 0.0 1104 446
13 0.3 0.0 1102 445
14 0.4 0.0 1100 443
15 0.4 0.0 1098 441
16 0.4 0.0 1096 440
17 0.5 0.0 1094 438
18 0.5 0.0 1092 437
19 0.5 0.0 1090 435
20 0.6 0.0 1088 433
21 0.6 0.0 1086 432
22 0.6 0.0 1084 430
23 0.6 0.0 1082 429
24 0.6 0.0 1080 427
25 0.6 0.0 1078 426

 

[gundrted]

BALLISTICS CALCULATOR

Load Number: AE357S2 Zero Range: 7 yd
Caliber: 357 Sig Temperature: 59 °F
Bullet Style: Full Metal Jacket Wind Speed: 0 mph
Bullet Weight: 125 gr Altitude: 0 feet
Ballistic Coefficient: 0.15 Max Range: 25 yd
Muzzle Velocity: 1350 fps Test Barrel: 4 in
Sight Height: 0.5 in


Range (yd) Drop (in) Wind Drift (in) Velocity (fps) Energy (ft-lb)
0 -0.5 0.0 1350 506
1 -0.4 0.0 1346 503
2 -0.3 0.0 1343 501
3 -0.3 0.0 1340 498
4 -0.2 0.0 1336 495
5 -0.1 0.0 1333 493
6 -0.1 0.0 1329 490
7 0.0 0.0 1326 488
8 0.1 0.0 1322 485
9 0.1 0.0 1319 483
10 0.2 0.0 1316 480
11 0.2 0.0 1312 478
12 0.3 0.0 1309 475
13 0.4 0.0 1305 473
14 0.4 0.0 1302 471
15 0.5 0.0 1299 468
16 0.5 0.0 1295 466
17 0.5 0.0 1292 463
18 0.6 0.0 1289 461
19 0.6 0.0 1286 459
20 0.7 0.0 1282 456
21 0.7 0.0 1279 454
22 0.7 0.0 1276 452
23 0.8 0.0 1273 449
24 0.8 0.0 1269 447
25 0.8 0.0 1266 445

 

[gundrted]

Science Baby

 

[Beefstews]

Science Baby

Good stuff! Thanks for all the info!