I have a P239 .40. It has 8/6 sights currently. I'd like to install a set of Ameriglo sights. What combination do I want in order to use a combat sight hold for the .40 and a 357 SIG barrel? Is this asking too much due to the calibers?

What distance are you going to zero the pistol?

quote:

Originally posted by sigwerkes2:
What distance are you going to zero the pistol?

Just common "fighting" distances...maybe out to 25 yards max.

REF: 2018 SIG WEBSITE FAQ SECTION
My SIG SAUER pistol is not accurate. Why? What should I do?

All SIG SAUER production duty/combat pistols are set up to use a “combat” sight picture. This is where the front sight completely covers the bullseye of the target. Using a six o’clock (“pumpkin on a post”) or center mass (“half’n’half”) sight picture will result in low impact. SIG SAUER, Inc sights in all non-sporting and non-target pistols for 2 inch groupings @ 10 yards. If you are still having trouble, please contact Customer Service for further help and instruction. Please have your serial number ready. There are also very helpful free Internet sites that cover pistol group analysis.

SIG Sauer pistols are also set up from the factory so that at a distance of 25 yards, the Point of Aim (POA) is the same as the Point of Impact (POI) — meaning that with a target at 25 yards, the round should impact the target exactly where the sights were aimed, with no compensation needed for bullet drop. At distances beyond 25 yards, the POI will be progressively lower than the POA.

If the slide has sights for 40 S&W to be point of impact/point of aim, then 357 SIG will shoot lower. Why?:

In JMB's delayed unlock action, the slide and barrel start moving to the rear upon ignition, while the breech end of the barrel cams downward towards unlock. This rear tilt down has the same effect as would tilting up the muzzle end. Since the 357 is moving faster than the 40, it spends less time in the tilting barrel and will strike lower than would be the case with the slower 40 that spends more time in the barrel and will thus leave the barrel at a slightly higher angle.