How many shots per group for best accuracy assesment?

1stmar asks me can if I can confidently say that group is not effected by your ability or environmentals?

Well, it sure is.

While my test groups are pretty darned good, they're about 1/3rd the size of what I've shot in competition. I've got a beating heart like my friend has as mentioned in the next paragraph.

A friend tested some specially sorted bullets in his Winchester 70 back in 1971 shooting several 10-shot groups at 600 yards that ranged from 7/10ths inch to 1-1/2 inch. Then he shot 40 shots into a single group measureing 1-15/16ths inch. Shooting the same rifle and ammo at the Nationals that year, his on-target groups in the 600 yard target's scoring rings were about 8 inches. Such is life when human pulse beat pumps muscles around to make even the best prone shooter's hold cover about 4 inches at 600 yards (2/3rds MOA)and those invisible subtle cross winds blow bullets around adding to that. The nasty icing on this accuracy cake is the aperture sights he used; not quite as precise as scopes. But he won all the 600 yard matches that year.

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603country supposes that if a fellow is going to be into competition shooting, working up the perfect load has more meaning.

I've seldom worked up a load for my own use. The loads used in the 800-yard group with my Palma rifle as well as both used in my .30-.338 mag at 1000 yards were what I got from others using the same cartridge in their rifles that won the matches and set the records. The only time I ever worked up a load was back in the 1960's when I tried a .264 Win. Mag. with Norma 139-gr. nickel plated match bullets; no body had used that cartridge in long range matches before. I don't prep cases in any way except sometimes turn necks to get their wall thickness spread no more than 1/1000th. I full length size fired ones. And new cases in my .30 caliber magnums have shot just as accurate as reloaded ones.

With 26 caliber and larger bores, I don't think working up a load has much benefit. Loads used by folks shooting most accurate are pretty much the same for each cartridge. What minute difference there may be is extremely hard to see and will cost a lot of barrel life getting it refined. Seldom does a handloader better what Black Hills or Federal (and sometimes Hornady) match ammo does accuracy wise. Especially if they test it properly (shoot enough shots per test group!!!)
 
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I guess anyone can plot what they want and overlap targets why no just look at each target and make the judgment based on that.

Everyone test their load different.
 
Bart that speaks to your ability, which frankly very few have and even at that, 250 shots perfectly placed? Quite a feat, but I will not question your ability. How about the environmentals? Over what period of time did this take? Too quick and the barrel temp is not the same from shot to shot, has that no bearing? Too slow and the ambient temperature changes. Again 250 shots and no risk that there was a gust of wind during the flight time that impacted flight.... My point is not to question your ability but to raise the point that more is not always better as it introduces more opportunity for other influences. That's hard to argue with..
 
When developing a load, I use 5 shot groups until I have the best three. From those 3, I shoot 10 round groups to determine the best. Chrono readings are attached to target. That gives me powder weight for bullet. Process is repeated for powder change. Usually 3 powders. Then best is selected. When bullet is changed, the process is redone.
 
I shoot 5 shot groups. Statistically not valid.

It is fun to me and does not interfere with the rest of my life.

There are so many variables, it is difficult to identify all of them. It is harder to try to isolate them.

Most of us do not shoot our load developments in a vacuum. There are a lot of external variables in play.

Every shot is wearing a little bit of the barrel in addition to heating it up.

I just don't have the drive to try to get that last bit of accuracy. I work at it until I am happy with the results.

I do see some folks out at the range who keep very detailed records of their loads and their groups show it. It is too much like work for me. I do this for fun.
 
Depends on the gun and use for it. My 300 Wby gets 3 shot groups and then it will string vertically and to the right a little bit. Not enough to make it unusable but ruins an otherwise good group. My Win 94 and my H&R .308 will shoot 10 shot groups as tight as my 3 shot groups before I get fliers. My M1 Garand I expect the first 20 to be in the same place as the second 20 and the third 20 shots. I adjust for 3 shots out of a cold clean barrel with most of my guns and call it good because in the field chances of more shots than that in quick succession are minimal.
 
I am interested in long range hunting. The first long range is I drive 1,000 miles to get there. In 2011 I practiced and was good enough to take a shot prone at animals at 500 yards, but to iffy at 600 yards. In 2012 I practiced with a different rifle and only was good enough at 400 yards.

So what can a terrible shot, like me, learn from Bart the great shot?
1) I have been undersampling with group size.
2) Early morning is a more likely time to fest in low wind.
3) Tuning the load to the rifle is work I might skip.
4) He is not using ball powder.
 
1stmar, I didn't shoot that 250-shot group. I've had it for a year or so since I downloaded it off the 'net and I now forget where it came from. It has about the same shot distribution from center to edge as the half dozen or so test targets from Lake City Arsenal's tests of match ammo at 600 yards. The arsenals best lots of match ammo shoot groups like that one but out to about 6 inches; twice the size as that one. It's the best group I know of that shows where most, some and a few shots go. The American Rifleman magazine had some of Lake City's groups of that ilk in print some years ago.

I don't think heating up a barrel has any effect on its accuracy unless it's not fit to the receiver right or not properly stress relieved. Too many folks have shot 30 rounds 20 to 30 seconds apart and no point of impact change whatsoever. LC match ammo's fired about that same rate for over 200 shots. There's no change to how the barrel vibrates as it gets hot. While the first shot from a cold barrel will typically be the lowest one in a long range group, the rest center about 1/8 to 1/4 MOA above it due to the hotter barrel heating up the powder in the case. If one keeps the loaded round in the barrel for the same length of time after loading it before its fired, there no problems.
 
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