Sight Radius Comparison

Yesterday I was rolling an idea around in my head about revolver sight radius vs. semi-auto sight radius. Since sight radius is a critical part of pistol shootability, I had it in my head that given a revolver and a semi-auto of equal barrel lengths, the revo would have a longer sight radius because of all the cylinder space behind the barrel. Fortunately, I have an M&P with a 4.25 inch barrel and a Ruger GP100 with a 4.2 inch barrel.

revolver vs semi-auto sight radius comparison

Turns out I was wrong. I’m actually a little surprised by that, but when you examine the two guns side by side it makes sense. The M&P has to have a whole bunch of stuff behind the barrel and chamber that makes the gun work, whereas most of the revolvers “make the gun work” mechanisms are housed in the grip or below the cylinder. The length difference is pretty visually clear and is a lot more than the 0.05 inches of difference in barrel length between the two guns.

I have a six inch revolver coming in for T&E soon, I’ll be interested to compare the sight radius on that to the sight radius on a 5 inch 1911. While I assume that the six inch wheelgun will have a longer sight radius, I’ll be interested to see just how much longer it is.


  1. I had it in my head that given a revolver and a semi-auto of equal barrel lengths…

    Measure both barrels from crown to breechface. 😉

    By revolver standards, that M&P’s only got a barrel length of three inches or so.

    1. Tried to post that this weekend. Using apples-to-apples barrel lengths makes the OAL comparison, “concealability”, more equal between the two and emphasizes that the auto in any given barrel length is going to have a clear sight radius length, “aimability?”, advantage.

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