The Anatomy of L.R. shooting. So...err...what is it?

[JohnKSa]

I agree but 2.999999 moa is close enough to 3.000000 moa to be insignificant.

For whatever it's worth, that is a true statement.

The problem is that the figure in question (when combining 1MOA and 2MOA) is not 2.999999 MOA, it's about 2.24MOA. 2.24MOA is significantly different from 3 MOA--especially to someone who's concerned with precision.

You'd actually be better off in this case approximating the result by simply using the larger of the two accuracy figures and ignoring the other entirely than you would be by adding them together.

 

[Bart B.]

The problem is that the figure in question (when combining 1MOA and 2MOA) is not 2.999999 MOA, it's about 2.24MOA. 2.24MOA is significantly different from 3 MOA--especially to someone who's concerned with precision.

Except when you test your free recoiling rifle and ammo with a 30 shot group and it's 2 MOA then dry fire 30 shots from prone and their call plot's 1 MOA, you can well count on the groups you shoot from prone will actually be larger than 3 MOA. Possibly 3.5 MOA.

Go do the statistics on that to explain why that's reality.

 

[JohnKSa]

Go do the statistics on that to explain why that's reality.

The issue has nothing to do with statistics, the problem is that there are two unjustifed assumptions in the hypothetical provided.

First, a call plot from a dryfire session does not tell the complete story as far shooter accuracy is concerned.

Second, the free-recoiling accuracy of a rifle does not fully characterize its performance from all shooting positions.

I responded to a comment about the combination of a 1MOA shooter and a 2MOA rifle. My response was based on the very reasonable assumption that those numbers were actually representative of the live-fire capability of the two systems and that the testing used to generate those representative figures (including the combined figure) is done under conditions that are reasonably similar.

If one has truly representative accuracy figures for the two systems and those two figures are 2MOA and 1MOA, then the resultant combination for the two systems, under similar testing conditions is going to be about 2.24MOA.

Nothing I've said was intended, nor should it be construed, to mean that it's impossible to construct a scenario whereby it's possible to combine a 1MOA shooter and a 2MOA rifle and get groups that are larger than 2.24MOA. That is certainly possible.

 

[Bart B.]

First, a call plot from a dryfire session does not tell the complete story as far shooter accuracy is concerned.

I agree. It's been known for over a century that the muzzle axis doesn't point to the same place when the bullet leaves as it did when the firing pin fired the round. But it's the best thing going these days outside of laser pointers that some international teams have used.

Second, the free-recoiling accuracy of a rifle does not fully characterize its performance from all shooting positions.

I disagree. Free recoiling rifles held the same way as people do will do that. Gripped at the stock's fore end and its butt plate held against a back support. Firing one so mounted lets the rifle to move rearward as the muzzle axis rises while the bullet goes down the barrel. Such machine rests do exist and have been and are used by top level competitors since the 1960's. Here's the one used by David Tubb:

The rifles accuracy with the ammo it shoots is fixed. It doesn't know how its held nor where it's pointed when shot. It performs the same for each and every shot. Where it's pointed and how it's held for each shot it totally controlled by the shooter. Which is why there's 1/4 to almost 2 MOA change in zero across several shooting positions for the same rifle and ammo combination.

 

[CharlieDeltaJuliet]

Go buy "Magpul: The Art of The Precision Rifle. Watch all the DVDs. It is a very informative video series. It helped me with the proper shooter position and with a slight pull I had when squeezing the trigger. I shoot a .308, and .243 at up to 800 yards, and a 50bmg, and 338 Win Mag past 800... The best thing is practice and being able replicate results over and over.

 

[1953greg]

i luv statistics!!!!!!!!

 

[JohnKSa]

It's been known for over a century that the muzzle axis doesn't point to the same place when the bullet leaves as it did when the firing pin fired the round.

And that is precisely the reason that the following statement can't be true.

The rifles accuracy with the ammo it shoots is fixed. It doesn't know how its held nor where it's pointed when shot.

Because the muzzle moves slightly in recoil between the instant of firing and the time the shot leaves the barrel, it will shoot to slightly different points of aim depending on how the recoil movement is affected by the way the rifle is held/restrained in recoil.

It shouldn't affect the accuracy on target too much as long as the hold is consistent, because from a given position and with a consistent hold the recoil behavior of the rifle should be pretty consistent too.

However, the fact remains that careful shooting from a well-designed machine rest will produce accuracy results that a human can not duplicate from a formal shooting position, even if that shooter can completely eliminate aiming error, wobble and flinch.

All that is assuming a rifle set up so that things like hand positioning and sling tension don't affect the point of impact to any significant extent. Those things are additional complications that can certainly make a big difference in the accuracy of some rifles when shot from different shooting positions.

 

[Bart B.]

Regarding rifles fired from good machine rests.....

It shouldn't affect the accuracy on target too much as long as the hold is consistent, because from a given position and with a consistent hold the recoil behavior of the rifle should be pretty consistent too.

Right you are. In my opinion, recoil behavior will be extremely consistant and won't affect the rifle or ammo's accuracy at all.

A friend shot a dozen or so 10-shot groups testing his Win. 70 based match rifle clamped in an identical machine rest as I posted above at 600 yards. The 308 Win. ammo groups were between 3/4ths inch and 1-1/2 inch. He then shot a 40-shot group with the same ammo that went into 1-7/8ths inch. When he hand-held the rifle slung up in prone shooting the same ammo, his groups were in the 7 to 8 inch range on target at the Nationals. He won all three of the 600 yard matches that year. Not too shabby for full length sized cases either.

The best competitors shooting prone hold their aiming area inside about 3/4 MOA. Then try to break their shots inside 1/2 MOA. Such is the way things are when our pulse beat wiggles the line on a Richter scale of vibrations. Best I've observed was in 1997 watching Corky Tyson set the 600-yard prone record shooting all 20 shots inside about 4 inches using aperture front and rear sights.

 

[JohnKSa]

Best I've observed was in 1997 watching Corky Tyson set the 600-yard prone record shooting all 20 shots inside about 4 inches using aperture front and rear sights.

I wish I had seen that. I really enjoy rifle shooting, but I do precious little of it these days.