Revolver sight radius

[Tatume]

Hello Folks,

I’ve heard people claim that a 5-1/2” revolver has a sight radius advantage over a 4-5/8” gun, and others state it doesn't. To investigate, I made a simple calculation. How much sighting error does it take to cause one inch of displacement at 100 yards?

I measured the sight radius of three New Model Blackhawk revolvers, at 6.50", 7.50", and 9.25" (4-5/8”, 5-1/2”, & 7-1/2” barrels). Error is calculated as (1/3600)*SR (sight radius). In order, the errors are 0.0018”, 0.0021”, and 0.0026”.

Based on there being only 0.0003” difference between the 4-5/8” and 5-1/2” revolvers, I doubt there is a practical advantage. With 0.0008” difference between the 4-5/8” and 7-1/2” guns (almost 0.001”), I believe this to be significant. I can see one thousandth, and I suspect most good shooters can.

I own several revolvers with 4-5/8” and 5-1/2” barrels, and I like them all. However, I’m not convinced that there is a significant difference in sight radius between them.

Some eagle-eyed readers may notice that the difference between the 4-5/8” and 5-1/2” barrels is not the same as the difference between the sight radii. On my stock Blackhawks the front sights are different, accounting for the discrepancy.

Comments?

Take care, Tom

[44MAG#1]

There is no practical difference between the 3. Sure there is a measurement difference but through shooting different barrel lengths and watching others shoot I have come to this conclusion:
If you can shoot you can shoot. If you can't you can't. If you are talking off the bench you will see some but not much advantage with a longer barrel due to them being more rest friendly.
If you think a long barrel will turn one from a mediocre shooter into average take a beginner to the range and watch them shoot both long and short barrels. They will still be mediocre. Period. Conversely thake top notch shooter to the range and watch them shoot. They will still be a shooter regardless the barrel length. They will vary more from time to time in their shooting than they will from barrel length to barrel length.
It does give one an excuse that the uninformed will buy when you have a bad day. "We'll if I would just have had a longer barrel I would have done better."
Yeah right.
If you can you can if you can't you can't. There is no magical help. Just practice and determination with a great foundation in the basics. Sight alignment, trigger control and accepting your movement with trigger control being the most important.

[runfiverun]

what does .001 translate to in inches of deviation at say 50 yds?

[44MAG#1]

Depends on the sight radius.

[Tatume]

what does .001 translate to in inches of deviation at say 50 yds?

For 4-5/8", 5-1/2", and 7-1/2" Ruger Blackhawks, the displacement attributable to 0.001" of sighting error at 50 yards would be, in order, 0.277", 0.240", and 0.195". Still not much difference.

[44MAG#1]

I'll add this too. I think this is an area where some put way too much importance on a small part of the equation that equals accuracy.
If you look at the shooting process it consist of the SHOOTER + gun + ammo + shooting conditions.
With the gun you have what you have. With the ammo you have what you have. Both can be toyed with and tricked up but to a point. With the SHOOTER you have the most unstable part of the unit or equation involved. How is one holding that particular day? Is your system calm, steady, doing it by the numbers and having the right mental focus?
Is the lighting situation ideal? Is it changing putting glare on the sights differently as time goes on? Can you read that glare correctly? One could go on and on about the SHOOTER but you get my drift.
When one tries to hitch his shooting wagon to one star such as barrel length he is trying to convince himself that he and his ammo is the most refined part of the equation which is not true. The said gun and said ammo is the most stable while the SHOOTER isn't. That is why barrel length is just an insignificant part of it.
Just like a top shooter can take a gun and load that will shoot a 2 inch group at 25 and out shoot an average shooter shooting a gun and load that will group 1 inch at 25. None of this piddling stuff will ever compensate for a shooter being refined in the art of shooting. Equipment is the least fragile of the equation.
Again: SHOOTER+gun+ammo=accuracy.

[fourarmed]

I will agree that there is probably no significant optical advantage to the longer sight radius. There may even be disadvantages: A short radius sharpens the rear sight when you are focused on the front, and a short barrel demands less follow-through. Furthermore, a long radius makes the front sight appear to move around more, and can lead to jerking the trigger. On the other hand, a long barrel has a larger moment of inertia, and holds steadier.

[kidmma]

How well you can see the sights.
How it feels in YOUR hand!

[Forrest r]

I'm not sure about the math in this post.

Several years back I contacted the armorer at the Alabama cmp & asked how many 1000ths should be taken off a front sight of an 03a3 for a 100yd zero. He said 8/1000ths were = to 1 inch (moa) for the 03a3 sights @ 100yds. The distance between the front sight & the rear sight is 32 1/4".

That would make for every 4" of sight length is = to 1 moa.

[Tatume]

I'm not sure about the math in this post.

Several years back I contacted the armorer at the Alabama cmp & asked how many 1000ths should be taken off a front sight of an 03a3 for a 100yd zero. He said 8/1000ths were = to 1 inch (moa) for the 03a3 sights @ 100yds. The distance between the front sight & the rear sight is 32 1/4".

That would make for every 4" of sight length is = to 1 moa.

Work it out yourself. It's a simple congruent triangle problem.

[Wayne Smith]

I agree with you, Tom. By the way, grips make more difference than barrel length.

[44MAG#1]

.008" on 32.25 inch sight radius will equal to .893 inch at 100 yards.

[Forrest r]

Thanks for the help guys!!!

I never was very good at math.

[MtGun44]

Math is a useful part of the toolkit of life.

Bill

[Forrest r]

Yup, math is a good thing, but I guess I keep using the new math. [smilie=b:

For some reason those #'s that were posted seem like they are 1/2 of what they should be.

If I use your #'s Mtgun44, you have a 32.25" sight length & an .008" front sight ='s .893" A100yds.

So if I cross multiply .008 times 6.5" & divide that # by 32.25 I should get the same #'s everyone else is posting.

6 1/2" ='s .0016" for .893" @ 100yds or .0008" for .4465" @ 50yds
7 1/2" ='s .0019" for .893" @ 100yds or .00095 for .4465" @ 50yds
9 1/4" ='s .0023" for .893" A 100yds. or .00115" for .4465" @ 50yds

That would make .001" of sight error @50yds =
6 1/2" (4 5/8 bbl): .56"
7 1/2"(5 1/2 bbl): .47"
9 1/4" (7 1/2 bbl): .39"

Like I said, I'm not the greatest @ math. But it isn't so much the difference in the amount of error between the bbls as it is the total error of the shorter bbl's in general. The longer sight radius is used on target pistols for a reason.

[Tatume]

Several days ago I explained this in detail in a PM I sent you. Did you not get it?

[44man]

It has a purpose. It depends on the rear sight clicks and how much it changes with each click. One click with a short barrel will move POI more, from one side of the bull to the other, up, down or sideways.
I liked the long barrel because my sight click moved POI 1" at 50 meters, 2" at 100, 3" at 150 and 4" at 200.
A better rear sight with less movement would allow a shorter barrel.

[44MAG#1]

Wrong the 45 ACP bullseye guns predominately were and are 5 inch barreled guns.
Look at the Smith md 52. No long sight radius on them either.
When it comes to offhand or shooting from field positions barrel length make so little difference that it is inconsequential.
There is no getting around that the weakest link in shooting is the shooter.
There is nothing magical about barrel length.
If you can shoot you can shoot if you can't you can't.

[44MAG#1]

That would make .001" of sight error @50yds =
6 1/2" (4 5/8 bbl): .56"
7 1/2"(5 1/2 bbl): .47"
9 1/4" (7 1/2 bbl): .39"
Wrong.

Right
That would make .001" of sight error @50yds =
6 1/2" (4 5/8 bbl): .277"
7 1/2"(5 1/2 bbl): .240"
9 1/4" (7 1/2 bbl): .195

[44man]

How far do you shoot bullseye? There is the rub, I am talking 50 to 200 meters.
Close range means nothing at all for sight radius.
The purpose for the longer barrel is to reduce the amount each click will move POI. Nothing at all to do with accuracy. Fixed sights do not matter either. Nothing to do with vision either until you get old and need arm extensions.
A very good and expensive rear sight will allow a shorter barrel. Clicks are smaller and more precise.
Please read what I said.

[44MAG#1]

You can say what you want. Barrel length means so little it is inconsequential. If one can shoot they can shoot. If they can't they can't.
No getting around it.
When one shoots bullseye and one is master class or high master they are GOOD no matter whether it is 25 or 50.
My observance of their 100 yard offhand one hand hold is that hey are STILL GOOD.
PERIOD. They have to be to be rated as they are.
If you can take a bad shooter with a 4 or 45/8's inch barreled revolver and hand him a long snout revolver and it turns him in a significantly better shooter I want to see it. Offhand that is. Just not on the bench or semi creedmore.
My observation at the local range over the years and watching people shoot gives me this conclusion:

If one can shoot they can shoot. If they can't they can't.

[44man]

All true, this has nothing to do with the shooter or barrel length, just sight clicks.
Really now, it is all I said.

[44MAG#1]

Anyone with common sense should know that if you have a sight that has a certain set of movement per click that click will move impact more on a short sight radius than a long sight radius.
That is a fact supported by mathematics and radian degrees and scientific calculations.
Even if one had a sight that is more precise and finer; the click will still move the point of impact more on a short radius than a long.
Period.
Who doesn't understand that on here? And if they don't, WHY?

[Forrest r]

Yes, I got your pm, thank you it was very well written & I though I learned something. Then I read another post & it had totally different #'s. So I'm simply asking why. It's really no big deal, I'm not questioning any ones ideas, or nit picking, etc.

Again thank you for taking the time to help me.

forrest r

[44MAG#1]

For one thing many make figuring angles and degrees something hard when it isn't. Forget trying to make something hard out of it and use common sense.

[44man]

Anyone with common sense should know that if you have a sight that has a certain set of movement per click that click will move impact more on a short sight radius than a long sight radius.
That is a fact supported by mathematics and radian degrees and scientific calculations.
Even if one had a sight that is more precise and finer; the click will still move the point of impact more on a short radius than a long.
Period.
Who doesn't understand that on here? And if they don't, WHY?
You must see that you agree with me. You push the issue but then come around to the truth.
Just a simple matter in the end.

[44MAG#1]

I didn't know that anyone disagreed with you that had any common sense. You pushed the thing about sight adjustment. I did not disagree with you because I am smart enough to know about the adjustment thing to begin with.
The original post was about sight error not adjusting the sights.
Reread the original post.

[44man]

Same thing. Vision. A short barrel is not less accurate. But your vision might make a close front sight a blur. I see three on some guns and have to pick one. Get the front sight out there and I will see it better. So can I add that to click adjustment?
I loved open sights when I could see. I had focus on both sights and the target. None were a blur.
I needed precise adjustments for each range and is why I shot IHMSA so good. Could I have shot a shorter barrel---YES, but one click might take me from the bottom to the top of steel.