[Ed]

What exactly makes a rifle inaccurate I guess is a better question. If you had match ammo and a solid rest for the fifle and took out the human equation and had no wind, the rifle would still make a group as opposed to 1 hole with multiple shots at 200 meters for example. I assume you would have some issue with barrel harmonics, what else could you get rid of to make all shots hit the exact same place? I ask kinda in a " I know it will never happen way" but from a scientific standpoint, could it be done?

[cslinger]

Well you would probably need a vaccum and you would probably need a barrel material that simply would not heat up or change even minutely from shot to shot. You would also need a rest or vise that simply did not move from the recoil.

You would also need bullets that were exactly the same from to another with no variation whatsoever.

There are so many factors that can mean a minute difference in impact here or there.

Chris

[Archie]

Harmonics.

The rifle barrel, action and stock have to react and vibrate exactly the same way for every shot. This requires proper bedding and attaching the barrelled action to the stock, and a barrel channel that does not bind up the (microscopic) movement of the barrel. Also, mechanically, the firing pin or striker has to give the primer a firm and strong blow.

Secondarily, in order for a human to get that accuracy out of the rifle, the trigger must be clean and as light as allowed for the type of rifle (bench rest rifles can have lighter trigger pulls than High Power rifles that can have lighter pulls than hunting or battle rifles.). The stock must fit the shooter, and be comfortable in that fit. The sights (glass or iron) must be properly attached and comfortable to use, not to mention usable in their own right; that is, clear in function, unlike the old Mauser barleycorn types.

All this assumes the ammunition is correct for that rifle. The charge must harmonize with the vibratory characteristics of the rifle. (Falls under the heading of load development.)

Does that give you a starting point?

[Ed]

Sure that helps, but I guess what I am asking is is it possible to build a gun that will put all rounds in the EXACT same spot? MAybe a barrel bedded in a concrete wall to stabalize it for all I know. I mean as a scientific project, nothing that you would carry. Just bored and wondering.

[Archie]

Okay, I get a better idea what you mean now.

No, I don't think so.

The long range bench rest guys build ultra heavy (30 to 40 pounds) rifles to shoot 1000 yard matches. The barrels look like an axle off a White Freightliner and the stocks resemble railroad ties or small orchards. Scopes are something one can observe Mars with.
I think the current record is just under 4 inches at 1000 yards.

Now, in order to make that less "variable", one would be tempted to bolt the action to a concrete block, perhaps? But then one would be stiffling the vibrations and probably causing the action to warp. Or the mounting bolts to stretch.

And after all that, back to what cslinger mentioned: atmospheric conditions. Even on a still day, there is some movement of air.

However, trying to get to that point is where the fun lies. "If'n it wuz easy, innybuddy could do it."

[hksw]

IMO, I think the area that would most affect precision in the environment you've described is ammunition. It is the most critical in getting small groups.

After finding a load that fits the harmonics, heat profile, idiosyncrasies of the rifle, fine tuning the ammunition is the only thing you can do. Uniformity, again IMO, is the key. The more uniform one round is to the next, the more likely they will behave in the same manner when they ignite, travel down and leave the barrel. You can only do so much to the rifle, but there is only one rifle - it is a fixed part of the equation. There will be a few rounds going through that rifle so for the rifle to place the shots at the same place every time, every round has to be the same.

Making the cartridges identical to one another to the point where the rounds will be going through the same hole will be expensive. You'll need tools to measure down to the individual kernal of powder, ensure concentricity of the the bullet to the case, ensure interior case profiles are the same, OAL, ensure the rounds are seated into the chamber the same, etc.

[bogie]

If you "bed" a rifle barrel in a big hunk of concrete, it'll do bad things. The recoil energy has to go somewhere.

[redneck2]

the biggest part of your answer is "the bullet" (assuming that cases, powder charges, etc are equal)

Back a number of issues, John Barsness of "Handloader" did an article about a machine (Juenke IIRC) that measures bullet concentricity

bullets that gave a poor read-out gave poor accuracy and vice versa

you could take a box of bullets, drop them on a concrete floor and alter the read out and accuracy

FWIW

[Publicola]

Test barrels often produce groups that are 1 ragged hole. I've seen pics of these 1 hole groups that accounted for 10 shots. This was under very carefully controlled conditions with (usually) carefully controlled ammo.

But if you have a perfectly straight & true barrel with perfect uniformity, perfect crown, precise chamber & ammo that is just as precise in terms of consistency in load as well as uniformity in bullet diameter & length, then under very carefully controlled conditions it would put 10 shots into the same diameter hole. At least in theory.

Most people that attempt to do this are trying to show off the quality of ammo more than anything. & some have come pretty close to what you're asking about. I don't think it's so difficult to control the barrel & firing mechanism to produce those results. The ammo is what usually provides the variables that cause deviation in a test barrel.

But one hole groups are possible. 1 hole same diameter as the projectile groups are possible in theory & may have been done. I just haven't seen them myself.

BTW, that 4" group at 1000 yards that translates into roughly .0078125 MOA if I'm doing the math correctly. It'd be 600 yards before the group size was .25 caliber. Nothing to sneeze at.

[Moparmike]

It could be done if you could map out the exact trajectory of a bullet over a given distance in a laboratory setting (ie compeletly still air) from a completely stationary rifle. With that trajectory mapped down to the hundreth-of-an-inch, you then build a pipe of about 2" diameter (for variation's sake) in the exact trajectory of the bullet and support it where it will not move at all, in any condition (ie wind, hurricane, nuclear explosion, earthquake, asteroids, 10-story japanese monsters, etc) and shoot that rifle through the pipe, which is attached to the target bulls-eye down range.

So in esscense, you have to build a 1000yd barrel or can.:eek: :cool: :p

[Swampy]

publicola wrote:

BTW, that 4" group at 1000 yards that translates into roughly .0078125 MOA if I'm doing the math correctly.


HUH???

A 4.0 inch group at 1k yds is (roughly) .4 MOA.

Where'd you come up with .0078.... something MOA ????

Curious.....

Best to all,
Swampy

[JPM63US]

About 6 years ago I found an article about a bench rest shooter who decided to go extreme, whicle still using a rifle which met some rules for light benchrest rifle (meaning it still looked like a rifle).

He concluded that the enviroment he was shooting in was his last unmanaged variable, so he found a warehouse to shoot in. Carefully controled the air movement and go to where he was making single hole 3 shot groups. In the end he had to put a backer on the target which indexed, so he could verify that the second and third shots actually went through the hole the first shot made.

Fun reading . . . unfortunately I lost the article.

JPM

[Publicola]

Swampy,
You are right. & no, I can't tell ya what the hell I was thinking; I'll just say I'm never letting my cats make my drinks again.

It is .4 MOA for a 4 inch group at 1000 yards (or more precisely 0.3819 MOA). ;)

But still, .4 MOA ain't nothing to be ashamed of.

[12-34hom]

Ed, if you have a chance pick up a copy of the Varmint Hunters Mag October issue.

The article where Steve Timm is having Gordy Gritters smith a Remington 700 Stainless long action [270] into a 6.5-06 Ackley improved.

Here's a list of what Gordy found after inspecting the Factory action.

Bolt lugs : bottom lug , contact surface of @ 25% - top lug had no contact with with locking lug recess.

Chamber : very crooked & off center to the bore.

Reciever face : 0.0015 out of true.

Locking lug recesses : roughly machined and not flat.

Reciever threads : off center and slightly crooked.

Now add : poor trigger, scope and mounts not properly installed and or lapped in, action of rifle not properly fitted into stock, it all adds up.

This is not exclusive to Remington rifles either, for what they are Factory - mass produced rifles are an excellent value. Just don't expect MOA accuracy from one out of the box.

12-34hom.