Looking for 1/2 MOA in .308 win

[42769vette]

1 moa is 1/60th of 1 degree. So half that.

He is asking about muzzle movement, not POI movement.

To be honest, I have no clue how to do that math, but if I were to guess, I would say a human hairish. I really dont know if that is correct, its a guess. Keep in mind thats a human hair when the bullet exits the muzzle, not as you break the trigger.

 

[rvb]

the math is so much harder than that. if we talk about muzzle movement, is the rotation point the back of the stock, the trigger, or...?
it's better to talk about reading the sights (calling the shot). then we can say how far is the gun moving when you break the shot? you need to be able to hold WELL under 1/2 moa. And you need to hold consistently (amount of cheek pressure on stock, amount of stock pressure on bags or bipod, how much pressure pulled into shoulder, etc etc) because consistency affects HOW the bullet leaves the barrel. All that is shooter input in addition to how much the muzzle moves. Then we can talk about ammo and std deviation (ammo accuracy). So... to reduce that to a some kind of math about how much the muzzle can move, well??? I need a full time salary for a couple weeks...

-rvb

 

[42769vette]

the math is so much harder than that. if we talk about muzzle movement, is the rotation point the back of the stock, the trigger, or...?
it's better to talk about reading the sights (calling the shot). then we can say how far is the gun moving when you break the shot? you need to be able to hold WELL under 1/2 moa. And you need to hold consistently (amount of cheek pressure on stock, amount of stock pressure on bags or bipod, how much pressure pulled into shoulder, etc etc) because consistency affects HOW the bullet leaves the barrel. All that is shooter input in addition to how much the muzzle moves. Then we can talk about ammo and std deviation (ammo accuracy). So... to reduce that to a some kind of math about how much the muzzle can move, well??? I need a full time salary for a couple weeks...

-rvb

If you could do the math for a full time salary, call me impressed.

 

[kennedy759]

twice I have shot 5 shot 100 yd 1/4 in moa groups with my rem 700 VLS with 3x9 leupold and harris bi pod and my sierra matchking reloads, me, the gun and ammo were dialed in. But they were once in a life time shots, most of my groups are 3/4in to 1 1/2 in with a few out to 2 inch with flyers. I saved the targets, one is one big hole and the other a clover leaf.

 

[rvb]

If you could do the math for a full time salary, call me impressed.

actually, I think id first need a couple weeks to get re-acquainted with some statistics and other math that I -once- new how to do... many years ago! haha

bottom line is, the muzzle can't move at all. none. because there are SO many variables that if your muzzle is moving 1/2 moa, as another person posted, you'll never come close to 1/2 moa group. probably more like 2 moa.

and that's all ignoring wind!

-rvb

 

[gglass]

To answer your question... The closest that you will get to a 1/2 MOA rifle under $1000 out of the box, is the Remington 700P (Police). It is a rifle that is not mass produced with the rest of the R700 line of rifles. It is made in the same part of the Remington factory as the M24 rifles, M40 base components and the 40X competition rifle. The 700P is a semi-custom rifle in that it is hand fitted with hand-selected barrels and receivers. It is then finished with the HS Precision stock.

The 700P is not advertised to the mass public because Remington would rather keep the price low for LE departments around the country. It is a rifle that Remington also voluntarily put onto the Clinton Assault Weapons ban list so that they could better keep it available only to LE customers.

I sold my previous R700 P to a LEO SWAT member here on the forums, but I posted many results in the sub 1/2 MOA range.

 

[T.Lex]

Yeah, I know all the variables. (All too well, since I can't keep them all stable.)

I'm just trying to get my head around how small a movement would be "allowed" and still get .5 MOA results.

Teeny tiny is about as close as I can get.

 

[ChristianPatriot]

Wouldn't be that hard to figure out. Put a guy on target and tell him to move his reticle an inch on target. Measure the muzzle.

 

[Woobie]

See, I can tell that that's English, but the application escapes me. Half of 1/60 is 1/120. (No comment on whether I first thought 1/30.)

And I probably wasn't clear about my question. How much can the muzzle move and still result in a .5 MOA group? 1/120 of an inch?

Notwithstanding the very astute observations made by Alan and RVB on this, let's play with this for the sake of argument.

If we say that the pivot point is at the trigger (which may or may not be the case depending on the rest) then we can say our pivot point is roughly 30" from the muzzle on a 24" barreled rifle. That length will be the base of our triangle. Now if we figure the tangent of an angle measuring 1/120th of a degree, then that number could be substituted for T in T=x/30, where x is our muzzle movement in inches.

If my math is correct, we are about .0043" in movement at its extreme. That's roughly half a hair, I think.

 

[T.Lex]

Notwithstanding the very astute observations made by Alan and RVB on this, let's play with this for the sake of argument.

If we say that the pivot point is at the trigger (which may or may not be the case depending on the rest) then we can say our pivot point is roughly 30" on a 24" barreled rifle. That length will be the base of our triangle. Now if we figure the tangent of an angle measuring 1/120th of a degree, then that number could be substituted for T in T=x/30, where x is our muzzle movement in inches.

If my math is correct, we are about .0043" in movement at its extreme. That's roughly half a hair, I think.

Dang.

So, I think that's about .1 mm?

 

[Woobie]

Dang.

So, I think that's about .1 mm?

Yeah. .1mm would be about .0039"

 

[42769vette]

Notwithstanding the very astute observations made by Alan and RVB on this, let's play with this for the sake of argument.

If we say that the pivot point is at the trigger (which may or may not be the case depending on the rest) then we can say our pivot point is roughly 30" on a 24" barreled rifle. That length will be the base of our triangle. Now if we figure the tangent of an angle measuring 1/120th of a degree, then that number could be substituted for T in T=x/30, where x is our muzzle movement in inches.

If my math is correct, we are about .0043" in movement at its extreme. That's roughly half a hair, I think.

I was always told, a Human hair is .007, so 1/2 a hair sounds right to me. Its not like this is something you can measure with a tape measure, but an interesting topic none the less.

 

[T.Lex]

Yeah. .1mm would be about .0039"

Oh sure. Now you're just splitting hairs. (Pardon the pun.)

I should start a post looking for 1/2 MOA hands.

Wait. That doesn't sound right.

Or maybe it does.

 

[rvb]

If my math is correct, we are about .0043" in movement at its extreme. That's roughly half a hair, I think.

that's taking every single variable, including ammo, out of the equation, and just some basic trig, eg if we were shooting recoilless lasers...
there's also movement around the axis (non-angular) to consider.

but it does show just how rock steady and consistent the shooter has to be. and why I'm 1 moa shooter on a good day.

consistency kills me. I don't spend enough time at it, incl dryfire. It's not usually the trigger control or alignment (sometimes it's alignment, darn astigmatism), but things like how much pressure between my cheek and stock, how much pressure it my shoulder, etc. It's building that position. I'll shoot 3-4 good rounds, then find myself adjusting, and not setting back up exactly how I was. It doesn't help I never shoot from a bench, only the ground. But for 3-gun I don't need to be sub moa, 2-3 moa from any position on demand and in a hurry is more important...

-rvb

 

[Woobie]

Yeah, the math is so over-simplified it's almost useless. But when I think about it in those simple terms, it almost seems like a miracle that 1 moa is possible.

 

[T.Lex]

Yeah, the math is so over-simplified it's almost useless. But when I think about it in those simple terms, it almost seems like a miracle that 1 moa is possible.

It probably is useless in a practical sense, but it helps me visualize the precision necessary. It also somewhat quantifies the... issues... with the OP.

Some of the variables, like axis alignment, are addressed with tools - like the reticle itself. Consistency in lining up the reticle will alleviate issues with lining up the axis.

But again, that .1 mm helps describe the range of acceptable error. It is very narrow. Very. And that's on the human side.

 

[Bsubtown]

...I forgot about Coriolis...

GOLD truly Gold.

 

[BStarkey 46947]

I read the attached article some time ago and it was very interesting. Might help: Secrets of the Houston Warehouse - Lessons In Extreme Rifle Accuracy - PrecisionRifleBlog.com

I also came to the conclusion 1-1.5 MOA is pretty darn good.

 

[halfmileharry]

Notwithstanding the very astute observations made by Alan and RVB on this, let's play with this for the sake of argument.

If we say that the pivot point is at the trigger (which may or may not be the case depending on the rest) then we can say our pivot point is roughly 30" from the muzzle on a 24" barreled rifle. That length will be the base of our triangle. Now if we figure the tangent of an angle measuring 1/120th of a degree, then that number could be substituted for T in T=x/30, where x is our muzzle movement in inches.

If my math is correct, we are about .0043" in movement at its extreme. That's roughly half a hair, I think.

...but my hair is really thin so the math is only estimated?

 

[T.Lex]

I read the attached article some time ago and it was very interesting. Might help: Secrets of the Houston Warehouse - Lessons In Extreme Rifle Accuracy - PrecisionRifleBlog.com

I also came to the conclusion 1-1.5 MOA is pretty darn good.

Great article, but I tuned out when I read that the guy only touches the trigger.

I'm sorry, but to me, that's not really shooting. It's pushing a button on a machine. Might as well automate it.

Now, that's not a criticism. Those guys achieve amazing results with the machine they use. Its just not something that appeals to me.