I have a few ?'s on testing loads.

How many groups does it take to get a good idea whether it will shoot or not?

How many shots in a group?

I've been shooting my Model 700 quite a bit lately, and have been trying different loads. I have been shooting 5 shot groups. It has a light-weight barrel, so it heats up after 3 shots or so, then I cool for a few min., then shoot the next 2. When I try new bullets, I load up 4 or 5 suitable powders, then shoot a few grains under the lowest max I find. After a couple groups, I have an idea what is working, and what isn't.

What do you do when working up a new load with a new bullet?

Tod, whether I fire a 3 or 5 shot group depends on how the first 3 do.

I do three (3 shot) groups with a 10th loaded case which is used for the fouling shot.
It has been my experience that 3 shot groups are plenty to decide if a load is decent or not. One problem with 5 shot groups, especially at 300 yards and beyond is that the wind plays a big part in the group size. I can put 3 quick shots in a target in less than a minute, but 5 shots just heats the barrel up too much.
This is my 10 shot routine.
Clean barrel with Hoppes #9, Sweets 7.62, Hoppes #9 till clean
Fire fouling shot at fouling target #1
Wait for about 2 minutes
Fire 3 shots within 1 minute at target #2
Let cool for 5-10 minutes till barrel is not warm
Fire 3 shots within 1 minute at target #3
Let cool
Fire 3 shots within 1 minute at target #4
Clean barrel before shooting next 10 shots.

The cooling off time gives me a chance to write down the velocity of each shot and sketch the grouping in my load development book.

If you are shooting some big capacity magnum, it might be too quickly but I normally shoot a 308 Win. 6.5-08, or 243 Win.

You can tell by feeling the barrel near the chamber after firing the fouler/3 shots and also seeing if the barrel feels a bit too warm and is unable to cool down within the 5-10 minute time period. Sometimes during the heat of the summer the barrel will not cool down enough just because it is so darn hot. I have that problem if the temperature is over 100 degrees.

I seem to remember reading in the Speer manual that a seven shot group is the best balance between number of shots fired and confidence in accuracy. That being said, last time I went out and tested for accuracy I shot a three shot group because of recoil.

Ben

Somewhere in my NRA reloading book is a bunch of statistical data which purports to prove the 7-shot group will work as well as 10 or more. That's a LOT of shots.

I do 3 shotters with the ones that are not particularly pleasant to shoot off the bench (like a 7-1/2# 300 Wby, or 9-1/2# 416 Rem), and 5 shots with the more user-friendly ones. BTW, a keeper load is not just one sub MOA group, because flukes happen too often. A load doesn't obtain "pet" status until it works at least 5 times.

Maybe not entirely on subject, but, when trying different load combos, I saw where green 788 mentioned in another post that he'll shoot one from Combo #1 at the first aiming point, then one from Combo #2 at the second aiming point, and so on, until all the rounds have been fired. Darn, here I thought I was the only guy who did that

R-WEST

I'm shooting a 260 Remington, so recoil plays no part in whether I shoot a 3 or 5 shot group. It usually takes me 6-9 minutes to shoot a 5 shot group. I'm only 15 min. from a range, so I'm never in a big hurry.

If I'm shooting partions, X's, etc, 3 shot groups will be used to save $.

What do you guys think is a good(not excellent) 5 shot group at 100 yards for a lightweight hunting rifle/hunting bullet combo? Something that is 'hunting' accurate to 300 yards?

Some say for varmint/target rifles you should shoot (5) shot groups & for big game rifles (3) shot groups. I find that if I get the same results after (3) groups, then that load seems dialed in. I've gone back months later & fired another group & the results are usually the same.
The .260 is one of those dual purpose rigs so I would shoot (3) shot groups w/ my deer loads & (5) shot w/ any varmint loads. A cronograph really helps & they are now cheap enough that every serious shooter should buy one. Good luck!

I use range testing to determine how a rifle will shoot in doing it's particular job. For a varmint gun this could easily be 5 or more shots in fairly short order. For a big game rifle however, I think a 3 shot group is plenty.

I draw a 1 1/4" circle (3/4" for varminters) around my desired point of impact (usually about 3" high @ 100) Then I'll shoot 3 as fast as I reasonably can. After that, I'll wait 15-20 minutes until the rifle is dead cold. Then I'll shoot another 3 @ the same aiming point.

If all six are in or cutting the circle, I'll figure that I'm good to go. If not, then I have to evaluate the group. I'm looking for pretty even distribution within the circle. If I see one flyer, then I'll usually assume that I maybe flinched one. But if there is more than one out of the circle, or if they are in scattered clumps, then I'll experiment further.

Whatever I decide on, I'll usually evaluate it more than one time, preferably in widely different temperatures if possible.

JimF

todbartell,
There is no set # as to how many rounds you have to shoot, every rifle is a little different. I have fired as many as only 2 rounds at 200 and called it quits - both shots where dead center.
I never fire over 3 shots for a group, reason why, I am using my rifles for hunting not scoring. So if the first 3 are not good then # 5,7 or 10th shot will make no difference.

If your barrel is light weight like my 700 ADL 270, then the 4,5, and etc will just get worse. What I do when I go to the range is I take along a long stem Thermonitor that you can get at garden stores. Then after 3 shots I slide it down the tube and wait until the temp. drops down to normal then shoot 3 shots again.

My rule of thumb is five shot groups for a standard chambering, three shot groups for Magnum chamberings. I wait at least one minute between shots. After I finish a load by accomplishing a one hole group consistently, I will shoot one shot through the cold barrel, take the target down and keep for comparing later. I will do this over several months and all temperature ranges. I will have numerous one shot targets that I can then superimpose over each other, this is my cold barrel group that really tells me something. That first shot at the animal in the field is the crucial shot, and that is the one I want to make good, in any condition I might encounter. This has worked for me from squirrels to Moose and Brown Bear. Good shooting.

I want to share a philosophy I have regarding shots fired vs group sizes. I keep notebooks to record all accuracy for my rifles, and over the years I have noticed a distinct pattern between 3 shot, 5 shot, snd 10 shot. It has proven to be very consistenet with the exception of only the very best benchrest rifles.

With a three shot group as a baseline:

a 5 shot group will 50% larger than the 3 shot

a 10 shot will be 50% larger than the 5 shot

therefore (due to percentages) a 10 shot group will be 125% larger than the 3 shot group.

This has proven remarkably consistent across rifle types and cartridges, and at all distances up to 1000yds. Again the only exception would be benchrest rifles that will show less change, more like only 30% between 3 and 5, and 5 and 10 shot groups.

Just recently I proved this idea almost exactly by my new FN SPR in 308 using Fed GM. The results were:

EX: 3 shot - 0.25"
5 shot - 0.375"
10 shot - 0.590"

It depends on what you are trying to establish, too. If you are trying to determine which benchrest load gives you a better result it's different than trying to find a hunting load for a 45/70.

In my PPC, I've shot a number of 5 sets of 5 groups to determine if a .005 increase in seating depth was better or worse. But, then, you are looking for a tenth of an inch, or less.

With my Whelen, if the first three shots are on the paper plate at 200, I'm done.

For my long range hunters, I usually do a standard work up, and even with 3 shot groups, you can usually identify quite easily where the "nodes" of the barrel are. In my experience, the "bad" groups tend to be twice as large as the "good" groups. So, if a combo of powder and bullets starts out a 3", the best I expect from that combo is 1.5". If my requirement is 1" for that load -- I quit RIGHT THERE and start on a different combo.

Much time can be saved by not beating a dead horse.

Even if that 3" group is outside of the "expected range" of that load, it'll never be a GREAT load. Of course, if the first group is 1.5", you don't know if it is going to go to the 3" side or to .75" side next.......

I do wish more loads would start at that .75" side, though. FWIW, Dutch.

for a big game rifle try shooting 1 shot today and leave the target up,go back the next day and fire 1 shot and the next day and fire one more.if they are an inch or less you have a good gun and load.
in most hunting situations the first shot is all that counts.if your gun will put that first shot where you need it the rest is a moot point.

I do a 7 shot group, letting the barrel cool after each shot and taking away the shot in the group that is the farthest away from group center.
that way I only have to shoot 5 o 6 diff. groups to be confident that I have hit the sweetspot.
Almost like the Speer manual #13 says.
Dumb book for anything else, by the way.

If the gun holds 3, then I fire 3. If it holds 5, then I fire 5. If it hold more than 5, I fire 5.

On big game rifles, I only fire 3 shots. I tend to like light, whippy barrels anyway, and it ain't gonna get any better with the heat. I'm more concerned about shot #1 than any... For varmit rigs, that's a different matter. I -want- to know what happens when the barrel heats up...

I think you should consider the use of the rifle, In Highpower we shoot some 10 shot strings in 60 or 70 seconds so that is how you test the loads. No use shooting 1 and waiting a minute to cool down, that won't tell you what it will do in a match. For a hunting rifle while I do believe 5 shots will be a help in developeing loads, you need to know how it shoots 3 rounds as fast as you accurately can, if it walks the shots you don't want to find out when you get that last shot looking back at you from 300 yards before a wounded animal dives into the thick stuff.

Eric has the right idea for a hunting rifle, most of which will put the first cold barrel round in a different place than a warm barrel group. However, if your objective is ten round groups for competition, then you need to fire ten round groups. So, to me the correct answer is, depends. sundog

It all depends on what you are trying to do. If you want to boast about how small a single group was that you shot in the past, then shoot fewer shots. As most of the readers here have pointed out, five shot groups are usually smaller than ten shot groups, and three shot groups are usually smaller than five shot groups. A one shot group (sic) really looks good on paper (unless your bullet was tumbling, of course). So, if you want to boast about how accurately your gun shot in the past, shoot only a few shots and only a few groups.

On the other hand, if you want to predict how well your gun is going to shoot in the future, you might want to shoot a few more shots and a few more groups, the more the better. Like many other things in nature (such a peoples� heights, or weights, or abilities, or the sizes of grains of sand on a beach), target group sizes follow a Gaussian distribution (the old bell shaped curve). There is a whole science, known as inferential statistics, that is devoted to predicting the sizes of things like target groups in the future, based on observations of the sizes of things like target groups in the past. The more observations we made in the past, the more likely our predictions about the future will be correct.

My opinion is, shoot several shots and many groups. And don�t discount the fliers. If you had a flier in the past, then you are going to have one at some point in the future, probably when you least expect it and when you least want it. Fliers are due to chance (things you can�t explain), and chances are the fliers will continue to happen. And don�t measure groups from the center of the two widest spread shots. Inferential statistics will tell you that will give you the worst prediction of what you can expect in the future because those two widest spread shots are the most subject to the effects of chance. Instead, measure the standard deviation of your shots, and average the standard deviations across your groups. With that number, you can predict the sizes of your groups in the future.

Again in my opinion, what you are really interested in is �if I fire some number of shots in the future, what size group can I expect most of those shots to fall into?� Stated another way, �if I shoot at something of a known size in the future, what is the likelihood that I am going to hit it, given everything I have observed about my shots in the past?�

Obviously, there is a point of diminishing returns (in terms of our ability to predict future group size) as we shoot groups with more and more shots. Inferential statistics tells us that 30 shots is realistically about the point of diminishing returns. Nobody in their right mind is going to shoot 30 shot groups. But seven shot groups work really well, and five shot groups work pretty well. Three shot groups don�t work worth a tinker�s damn. This can all be shown mathematically. Trust me, fewer shots just give you a larger standard deviation, and make your future predictions of group size less accurate (and, statistically, larger).

I assume that nearly all of us on this forum are shooters. I also assume that very few of us on this forum are inferential statisticians. If you want a very simple computer program that will predict future group sizes from a single group that you shot in the past, you can download one for free from The Home of AccuLoad . If you want an extremely sophisticated program that will help you predict all kinds of things about your future shooting, based on all the information that you have collected about your shooting in the past, then you can find that there as well (but, that one isn�t free).

I apologize for getting up on my soapbox. It�s just that the answer to the original question does not have to based on opinion. There is a very scientific answer to the question. Others have already worked out the answers. And the benefits of their work are available to anyone who wants it.

Go Geek!
Although I'm forever analyzing data using formal statistics at work, I tend to ignore them when hunting, trapping reloading etc. Denial likely, or trying to stumble on the great mysteries rather than deducing truth in the most efficient way possible. Its good to be reminded that these things are, in fact, quantifiable and that with just a small increase in dicipline on my part I can spend less time (and powder) finding a load and more hitting what I'm shooting at. Appreciate the reminder.

Thanks also to the guy with the data on how group sizes grow by number of shots taken--I'll start keeping better records and see if it holds for my rifles.

Good thread.

I always load 9 cartridges of a load I want to test. I fire three 3 shot groups and if the ag isn't what I'm after I'll make an adjustment to the powder or seating depth and load another 9 rounds.
If the first two groups are really bad, I'll save the last three rounds and pull them apart when I get to the loading bench. When that happens I'll usually make a major change in seating depth and start over.

I'll do a run of ten and shoot two five shot groups,if things look good,,I'll do a string of twenty shots,in twenty minutes, keeping the same point of hold.

Since I am not a benchrester and no longer a "competitor" the only bench work I do is for load development. When starting with a new rifle I know what BULLET (one rifle, one load) I wish to use as that has been dictated by the game hunted. Primary shooting can be accomplished by shooting pairs and final load tuning with 3 shot groups for single shots and bolt guns and pairs for doubles. When all this is done the most important thing for me is to see how the rifle shoots its first shot from a clean treated bore and its second shot from a fouled bore over the long haul. The 24 shot group is an enlightening way to see this, just clean your rifle and treat the bore, push a TIGHT clean patch through it and fire your first shot and your second shot. Now take down your target and repeat every month for a year. This is real world hunting accuracy, the kind that is really usefull. IMHO. Richard

For big game rifles, I use 3 shot groups, varmit or sniper guns I use 5 shot's groups.

My mind plays tricks on me so the most accurate rifle I have is actualy probably my least statisticaly accurate rifle. My 7x57 shot it's chosen load well in a 3 shot group once. I cut the group out and stuck it on my guncase to remind me if I ever missed (it took a year which helped too)and since then have limited paper shooting to deer silhouttes or a single check zero shot.

My 6.5x55 has shot a one hole group and a lot of half inchers but I've played about with it a lot so some have been poor. Somewhere in the back of my mind is a little voice that tells me it is less reliable as a result...

[ 08-20-2002, 14:37: Message edited by: 1894 ]

I much prefer 6 or 7 shot groups. I'll fire three in aout 2 minutes, let the barrel cool and then fire two, let it cool, then the final one or two, all at the same aiming point.

I read the original article in Handloader or Handloader's Digest or somewhere showing the dry statistical validity of 7 shots. And like GunGeek said, the more the sample the better the validity of the testing.

But the 6/7 shot group also shows any "pattern" better, such as a tendency to walk. A 5/8" three shot group in a "sort of" horizontal line - is that rifle really stringing or is it just statistical probability? Is it just wind? Would the next four shots turn it into a 5/8" round group or would they string out even more? Seven shots will definitely show whether the rifle shoots nice round groups or not.

Also, I can load 6 of each different charge weight or whatever and with only those 6 shots I can get a very good idea of whether to try more with that combo. If it looks really good I'll come back another day with 7 of that load - if it still shoots to my expectations then I know it's a good load.

Three shot groups are good for bragging - I've fired several from 1 1/2" rifles where the first three just happened to go sub-MOA by quite a bit. But there is something really confidence building in seeing a nice ragged hole chewed out of the paper even if it is 1" across.

Todd,

You stated that you usualy start with the bullet you want to shoot and 4 or 5 different powders a few grains under max to give you an idea what is working and what is not.

You could be passing over some pretty good powders this way. I have found that the most accurate load is often near max. but not the rule.

Especially with sporter weight barrels I have found that changing the charge weight one half to one grain either way could and often does make quite a difference.

[QUOTE]Originally posted by todbartell:
Since I load at the range my testing is alot different than most. On my hunting rifles I will shoot say 3 shot groups once I get a load thats show promise I will good back to the range and shoot the same load but will do it with 5 shot groups. Clean between 5 shot groups let the barrel cool. My next trip to the range will be to shoot 20 rounds at 200 yds. Between letting the barrel cool and cleaning it may take afew hours. I'm looking for a group about 1" to 1 1/2" at 200 yds and if all goes well than I will go back and shoot at 300 yds on another day. For me the most important shot is the first one as that is the one that counts. I also chronograph the loads. On my varmit rifles I shoot 5 shot groups. And once in awhile I will do a 10 shot group. Once I select a caliber and have the twist I pretty much have the bullet and powder done. I try and not wear a barrel out testing. I'm working with a new 300 win mag with a lilja fluted barrel and muzzle break and I hope too hunt elk and deer with it this year. I'm also working with a 30-338. Well good luck to you all!
Tom