Question for sig guys and anyone else

[68ar15]

The sg 553 lb and the Sg 551 sb have very similar barrel lengths and ought to have very similar velocities. The 553 lb has a rear sight drum with a v notch a 100m aperture a 200m aperture and 3000m aperture. The 551 sb has v 200, 300 and 400 meter apertures.

I don’t have much use for the 100 m setting as I find a 200 m zero good enough for muzzle to 250m or so.

My question is would the 551 sb drum work on the 553 lb? Or would the shorter sight radius of the 553 introduce too much error in the calibration throwing things off? Which way would it be off? How much?

Thanks in advance

[JoshNC]

Just choose the diopter you want to use and zero with it. You won’t adjust to different diopters for different ranges at the distances you will shoot irons. Don’t over complicate this.

[68ar15]

I do though. I’m shooting at 500. At 400 with the diopter on 3 I can hold top of head and get hits on Ipsc steel. If I had a 4 setting I bet I could get hits at 500 without shooting at the sky above the target.

Thanks anyway.

[JoshNC]

I’ll mic a couple 550, 551, and 553 diopters to see the height differences this week and get back to you. If the 200 and 300 apertures are the same, the 551 drum probably would work.

[68ar15]

Oh wow thanks!

[JoshNC]

I haven’t mic’d any yet, but eyeballing a 552 drum and a 551 drum, the heights of all the diopters look identical, only the markings differ. The 552 has notch, 1, 2, 3. The 551 has notch, 2, 3, 4. I will pull my diopter sight 552, 551, and PE90 from the safe this week and have a look.

[68ar15]

Thank you for taking the time to look into this.

[68ar15]

The more I think about it the more it seems that with a shorter sight radius the same change in rear aperture height would yield a greater elevation of the muzzle in MOA.