I have been working a load for my 22-250 useing the ocw method. I have decided on a charge weight 35.5 Reloader 15 moved seating .010 went from 1/2" to 3/8" thies are 3 shot groups. I am going to make up some more with this recipe & give them a try. How many shots till you are convinced you are their & just not a couple good shoots. How do you eliminate the occasional bad shot.

You're likely to get the worn out rhetoric that you'll need five seperate five shot groups to know that you have an accurate load. I'm not in that camp.

One of Speer's statisticians worked out a formula that showed that a single seven shot group gave a good level of confidence in the load without wasting an excess of material and barrel life.

As for getting rid of the occasional "WTF? " shot, good luck... I don't believe it is possible. You can of course minimize these shots with a well developed load, which is what you've done.

The OCW load will be pressure tolerant to a much higher degree than conventionally developed loads, and this alone will buy you a certain amount of freedom from flyers.

Human error can never be factored out, of course. And this fact alone is what makes the 25 shot aggregate that BR types place so much significance on superfluous as criteria for judging the rifle's or the load's integrity. Pulled shots which spoil the aggregate are almost certainly human error--even when we swear we didn't pull that shot!

A rifle and load that shoots MOA most of the time will likely shoot MOA all of the time, provided it is being properly fed and fired. Shots that meander outside this limit must first call the shooter's prowess into suspect, and secondly the ammunition components (not necessarily the recipe), and only then suspect the integrity of the rifle and the load recipe.

Take care,

Dan

If I take the rifle out 3 or so times with the same load shot 3 groups each time out. They are all were I want them I have it. So that is 9 groups or so.

Minimum of 7 shots for statistic trustworthiness.

BossMoss,
The key is to go to the range on several different ocassions. If the load is stable and accurate several trips to the range will verify that. If it's a hunting round then two shots from a clean cold barrel - if it's for competition then 5 shots from a warm fouled barrel.

PaulS

Let's see.... "Eight is Enough".... no, that was a movie title.

The answer to your question depends on how precise you need your answer to be.

As a rule of thumb, a rifle that truly averages 1" groups, long term, will regularly print .5" to 1.5" groups, with exactly the same "input" conditions. That is, a 5 shot group anywhere in that range of sizes represents no detectable change in technique, ammo, rifle condition, etc.

Five 5-shot groups still leaves a lot of leeway in estimating true group size. A complete answer is fairly complex, since the math is an F test, and there is a whole huge family of F curves.

For my purposes, five 5-shot groups would probably not be enough.

5 (five) 3-shot groups should tell you everything.