Two over ten?

[Thofer]

Thanks for accepting me into this forum and I come with a question that has been hounding me for some time. This is what a shooter said in the 1960 era and I have not been sucessful in finding out the meaning of the statement , thinking somebody on the chat might have some info on it: (. Any two-over-ten bore in a 22 rifle, it crosses it line of fire at twenty-five yards; is in again at fifty, just the same, if it is two-over-ten.) I believe he was talking about a Winchester model 75. Might be a old timer will be familiar with this terminolgy? Any input is appreciated.. thanks

 

[dbledoc]

Here is an article that explains the idea for a 223.

The Mythical 50/200 Yard Zero - Uncle Zo

Ever have someone suggest to zero your rifle at 50 yards because that will provide a secondary zero at 200 yards? Ever heard a broken clock is right twice a day? Let's take a closer look at the mythical 50/200 yard zero.

unclezo.com

Basically it is a concept based on the ballistic curve of the projectile. The bullet begins to drop as soon as it leaves the barrel. So you angle your rifle up. So for the 22 you zero your rifle sights so that at 10 yards it hits the target 2 inches high. The bullet will then follow a parabolic curve going up and then crossing the zero at 50 yards.

 

[robmints]

Thanks for accepting me into this forum and I come with a question that has been hounding me for some time. This is what a shooter said in the 1960 era and I have not been sucessful in finding out the meaning of the statement , thinking somebody on the chat might have some info on it: (. Any two-over-ten bore in a 22 rifle, it crosses it line of fire at twenty-five yards; is in again at fifty, just the same, if it is two-over-ten.) I believe he was talking about a Winchester model 75. Might be a old timer will be familiar with this terminolgy? Any input is appreciated.. thanks

Idk. But welcome to another downtrodden state. I often watch William Kirk. Washington Gun Law site.

 

[eruby]

Welcome aboard

IDK either, but I got some salmon from Seattle last September

 

[Melnic]

Here is an article that explains the idea for a 223.

The Mythical 50/200 Yard Zero - Uncle Zo

Ever have someone suggest to zero your rifle at 50 yards because that will provide a secondary zero at 200 yards? Ever heard a broken clock is right twice a day? Let's take a closer look at the mythical 50/200 yard zero.

unclezo.com

Basically it is a concept based on the ballistic curve of the projectile. The bullet begins to drop as soon as it leaves the barrel. So you angle your rifle up. So for the 22 you zero your rifle sights so that at 10 yards it hits the target 2 inches high. The bullet will then follow a parabolic curve going up and then crossing the zero at 50 yards.

With iron sights? That would assume bullet velocity. I guess a long time ago, there may not have been so many choices?
still does not make sense that its 2" high at 10ft. that would need to be a pretty slow bullet (22 Quiet?)

 

[outrider58]

This diagram helps explain. Given that a bullet begins dropping as soon as it leaves the barrel, You are always aiming upward allowing the bullet to hit the 50 yard zero on its way up, then hit the 200 yard zero on its arc downward.

I'm not sure this answers the OP's question.

 

[LGood48]

Greetings.

 

[AssMan]

Does the 2/10 refer to twist rate?

 

[Thofer]

Here is an article that explains the idea for a 223.

The Mythical 50/200 Yard Zero - Uncle Zo

Ever have someone suggest to zero your rifle at 50 yards because that will provide a secondary zero at 200 yards? Ever heard a broken clock is right twice a day? Let's take a closer look at the mythical 50/200 yard zero.

unclezo.com

Basically it is a concept based on the ballistic curve of the projectile. The bullet begins to drop as soon as it leaves the barrel. So you angle your rifle up. So for the 22 you zero your rifle sights so that at 10 yards it hits the target 2 inches high. The bullet will then follow a parabolic curve going up and then crossing the zero at 50 yards.

I do understand that concept, but what my question is was the shooter referring to a combination of bore twist in conjunction with land and groove in bore of rifle?? Two over ten , could he have been referring to a certain size of bore??

 

[Thofer]

Idk. But welcome to another downtrodden state. I often watch William Kirk. Washington Gun Law site.

Thanks, we do get a ton of washing!!

 

[Thofer]

Does the 2/10 refer to twist rate?

Wonder that myself, or land and groove depth of cut?? Or a combination?

 

[Thofer]

Welcome aboard

IDK either, but I got some salmon from Seattle last September

Thanks , but you missed out on the Dungeness crab?

 

[Bountied]

This diagram helps explain. Given that a bullet begins dropping as soon as it leaves the barrel, You are always aiming upward allowing the bullet to hit the 50 yard zero on its way up, then hit the 200 yard zero on its arc downward.

I'm not sure this answers the OP's question.

View attachment 434297

From that image it looks like it's going up then down. That's an odd trajectory.

 

[Bountied]

 

[AlBeight]

From that image it looks like it's going up then down. That's an odd trajectory.

When you point the barrel upward, the bullet DOES go up at the muzzle and then down after its apex.

 

[Uncle Duke]

Does the 2/10 refer to twist rate?

Wonder that myself, or land and groove depth of cut?? Or a combination?

I don't recognize that terminology. Somebody will likely be along who can perhaps answer that question.

But standard rifling for 22lr is 1 in 16. So whatever the term refers to, it doesn't appear (to me at least) to be rifling related.

 

[Bountied]

When you point the barrel upward, the bullet DOES go up at the muzzle and then down after its apex.

Yes, it does. I was making fun of the rudimentary graphic.

 

[Bountied]

He mentioned bore. Is this a sight height over bore question? Scope 2" up over 10" of barrel? Seems odd. Or maybe scope objective diameter math to get the right height scope rings? Can the OP shed more light on the context of the 2 over 10 question?

 

[Bountied]

Below is a formula to help you be a little more precise when determining sight height.

1.) Measure the bolt diameter and divide it in half.

2.) Measure the scope tube diameter and divide it in half. 1.000” / 2 = 0.500” (for 30mm tubes use 1.181”)

3.) Measure the distance from the top of the bolt in the rifle to the bottom of the scope on the rifle.

4.) Add the numbers found in the steps 1-3.

Example: Remington 700 .308 with a Leupold Mark 4 M1 Extended Range Tactical Riflescope, 6.5x20x50mm

1) Bolt diameter .696". .696"/2= .348"

2) Scope tube diameter 30mm 1.181/2= .591"

3) Distance from top of bolt to bottom of scope = .75"

Sight Height = .348" + .591" + .75" = 1.68"

The most common sight heights run from about 1.5 to 1.8 inches above center of bore.

 

[Dave MP]

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