This Accuracy Thing

[Engineering101]

Greg

I'm a hunter so I figure 4 shots in 0.5 MOA is good enough but will take worse depending on my intended use for that particular load. However I don't leave it at that. When I'm doing load development on a new rifle I always take a few other rifles and fire one shot from them - usually at 200 yards but sometimes further. If the bullet hole is within 0.5 MOA of point of aim, I figure the rifle and me are still doing our job. If not, I figure out what went wrong.

If you want to add some science to this whole thing, rifle accuracy is a Gaussian distribution and you can compute statistics about it until you are blue in the face. I don't. I just took note that it takes at least 4 shot groups to get a statistically meaningful idea of what to expect from your rifle.

For my prairie dog guns I do it a bit different. To prove out a new load, I shoot 10 shots at 200 yards and if they all land on my virtual prairie dog head (about the size of a 50 cent piece), I call it good and go shoot p-dogs. Interestingly I almost never miss inside 200 yards but past 400 yards the wind usually makes it pretty tough.

 

[MMERSS]

I view group size (precision) with only half validity without including the velocity spreads. I strive for an ES (not SD) of around the low teens or less along with group size of .5 MOA or less. Otherwise I'm back to development. Why?

Bryan Litz in his new book Modern Advancements in Long Range Shooting explains this well. He conducted an analysis with shot hit percentage on a 10" circle at 1000 yards with a .25 MOA 15 fps SD gun compared to a 1 MOA 5 fps SD gun. MOA was determined at 100 yards. Any speculation which gun produced more hits at 1000 yards? Was the hit percentage increase of one gun compared to the other rather noticeable?

Group size is worthy of only so much without the other variable and intent to consider….but a good place to start.

 

[MMERSS]

A better and shorter answer set the target at long range, beyond 350 or so and fire 1 shot per day for 5 days. If you keep 'em within a half MOA of Point of Aim I'd say you're good to go.

And, ya gotta count every shot!!!!

Pretty much sums it up!

 

[davkrat]

My goal for bi pod and rear bag is always the same. Everytime i go out and from every distance i try to shoot within 1moa of point of aim. If you can do this consistantly youre a pretty bad dude.

When i get set up and steady or shoot for group regardless of poa, 1/2 moa is pretty typical.

Within 1 MOA of POA is exactly what I get if I hit one of my 2 MOA gongs. I know if I can hit them there isn't a big game animal I can think of that would survive. Maybe not DRT with an edge hit but probably hurt enough to not go far and enable a clean up shot.

 

[justgoto]

If I notice my scoped bolt action shooting over .5MOA; I begin searching for the problem.
If I notice "fliers," I begin searching for the problem.

 

[davkrat]

Can you maintain .5 MOA off a 30 degree slope in slipping shale off of sticks or is that off a bench?