Unusual grouping, round robin test.

[Tarakai]

Hi guys I have been load developing and have come across an unusual situation with a group. The attached picture says it all. Details as follows.....
. Ruger M77 tang safety in 243 win
Testing at 100m, minimum of two minutes between each shot.
Once fired brass, neck sized only, federal large rifle primer, seated 10-20 thou off the lands. Ar 2209 powder
87 gr hornady Bthp
The round robin test shot off the bench started at 41.6 with a clean bore. The larger grouping here testifies probably to the clean bore which at around 2 Moa is poor. The second group at 42 gr has 3 rounds all touching with one flyer 1 Moa to the left. 42.4 gr shows the group going back out to 2 Moa. 42.8 gr the group is back to 1 Moa. 43.2 gr group shows plenty of vertical stringing. The max reccommended charge is 43.5 gr from ADI manual.

From the results I guess next testing should trial around 42 gr.mark. What I am perplexed is why is the 42 gr. load is grouping LOW in comparison to the 41.6 group ? Is it just the nature of a clean bore in this particular rifle this is happening?

Thanks for any feedback and advice
PHIL

[Gamerancher]

Wind/mirage conditions changing? Taking 2 minutes or more between shots means that your testing was over an extended time frame. Plenty of time for conditions to vary from group to group. Benchrest shooters shoot a "condition", when wind/mirage is the same as the sighters they were happy with. I've watched Stuart Elliot, ( one of our best shooters ), fire his scoring shots off as fast as he could. I asked him why and his reply was, " I liked that condition".
When trying to shoot groups you really have to be honest with yourself, "was that a good shot" is something you have to always think about.
Also, one apparent "good" group is not a true indication of accuracy. Load a bunch of cases up with that load and go and fire at least a half a dozen 5 shot strings. If it holds up, then you have a "true" indication of how it shoots. More over, the average of those groups is a better indication of how accurate it is.

[Wm.Traynor]

FWIW, you have a great group with 42gn. No vertical stringing to speak of in the context of a hunting rifle anyway. Barrel harmonics put the group where it is. Simply adjust the sight to where you want the zero and go from there

[Apollo]

Stuart Elliott is very practiced at that game and shooting fast strings. When one has the experience you know as soon as you fire the shot if it's going to be good or not without even seeing the shot fall on the target. Have a look at this clip, watch for the 8th Shot that Stuart fires and he knows it was not good. Like us all, we try and shoot a group under the same conditions for each shot, if conditions change it's wait for them to return to normal within your allowed time frame.

https://www.youtube.com/watch?v=03qtXpoObfM

These are very heavy barreled rifles so it does take a bit for them to get hot. Something you can't do with a light hunting barrel type rifle.

Two minutes between shots is not good in my view. As mentioned too long between shots and things can change quite a bit in that time. With a light weight barrel and doing load testing I would tend to have 5 rounds ready. From a cool barrel, fire one shot at a sighter target, then the four at your main target with little break between shots. Say 15 seconds or so but not 2 minutes. Then I would let the barrel cool to at least luke warm and do the next set the same. Keep feeling the barrel around the chamber area or just forward and don't let it get too hot. It's touch and go with very light barrels that are not designed for multiple shots in a small space of time.

Varmint weight barrels are a lot better.

Once you have your best effort and settle with a good load clean the bore, let it go cold as it would be without having fired a shot. Sight your scope to the first cold shot like would happen when you are out hunting if that is what you will be mainly doing. After time you will learn where each shot falls from cold so you can adjust easily.

[marksman]

the reason your 42 gr group is lower is the load is clocking, just a different harmonic release of the bullet
do I understand that you are shooting groups at each load or shooting 1 shot of each load round robin like in ocw
I would only be shooting 3 shots at a time then letting the barrel cool down completely, maybe 15-20 minutes depending on weather while doing the test
the 42 gr group looks like you may have pulled the trigger to the side, depending on how fast it is going it would be the one to look at

[Mitch]

Horizontal spread is ok, normally wind etc. Vertical is bad. Go 42 as it has least vertical

[Gamerancher]

Yes Apollo, I wasn't suggesting that the O.P. shoot fast, I was merely indicating, (as you re-iterated ) that shooting under as close as possible to same conditions will give better results. Plodding along at a pre-determined pace may sound like a good idea, but, in the real world, it is better to shoot to conditions.

[Apollo]

I'm with you, know exactly what you mean.

BTW... Loading and extracting rounds like Stuart is doing created a name called "The Bum Feeder" but it was for a specific reason. The action he was using was a Short Action and the chamber port is too short to feed or extract a case the normal way so the bolt stop was removed and hence fed from the rear.

I obtained a rifle from Stuart that belonged to a mutual departed friend of ours and it too has the bolt stop removed. Bit of a trick to remember the bolt will fall out if you aren't careful. Haven't tried Stuarts trick as yet but it's only a 6mmPPC so it loads and extracts a case fine.

Let's not forget Annie Stuart, she is every bit a world class shooter of the highest standard and has some great knowledge to share in order to help others. I look forward to catching up with them both again at a match somewhere.

[bladeracer]

Hi guys I have been load developing and have come across an unusual situation with a group. The attached picture says it all. Details as follows.....
. Ruger M77 tang safety in 243 win
Testing at 100m, minimum of two minutes between each shot.
Once fired brass, neck sized only, federal large rifle primer, seated 10-20 thou off the lands. Ar 2209 powder
87 gr hornady Bthp
The round robin test shot off the bench started at 41.6 with a clean bore. The larger grouping here testifies probably to the clean bore which at around 2 Moa is poor. The second group at 42 gr has 3 rounds all touching with one flyer 1 Moa to the left. 42.4 gr shows the group going back out to 2 Moa. 42.8 gr the group is back to 1 Moa. 43.2 gr group shows plenty of vertical stringing. The max reccommended charge is 43.5 gr from ADI manual.

From the results I guess next testing should trial around 42 gr.mark. What I am perplexed is why is the 42 gr. load is grouping LOW in comparison to the 41.6 group ? Is it just the nature of a clean bore in this particular rifle this is happening?

Thanks for any feedback and advice
PHIL

I like that 42.4 and 42.8 have little elevation change, could be worth looking for best accuracy in that zone.

[Tarakai]

Thank you all for your feedback it is appreciated. Yes this was a round robin ocw test. ....... first shot 41.6 top left square. 2nd shot 42 gr top right. 3rd shot 42.4 gr bottom right. 4th shot 42.8 gr bottom left. 5th shot 43.2 gr centre square. Clean bore, then repeat a further 3 times.

I will do further tests including 4 consecutive shots for each powder load. It is interesting that the harmonic sweet spot (42 gr) POI is lower on the target. Being a simple factory ruger hunting rifle I would be happy with 3 rounds touching at 100m

[bladeracer]

Thank you all for your feedback it is appreciated. Yes this was a round robin ocw test. ....... first shot 41.6 top left square. 2nd shot 42 gr top right. 3rd shot 42.4 gr bottom right. 4th shot 42.8 gr bottom left. 5th shot 43.2 gr centre square. Clean bore, then repeat a further 3 times.

I will do further tests including 4 consecutive shots for each powder load. It is interesting that the harmonic sweet spot (42 gr) POI is lower on the target. Being a simple factory ruger hunting rifle I would be happy with 3 rounds touching at 100m

Hmmm...I think it was a mistake cleaning the bore for every shot in the one group. I wouldn't have cleaned the bore at all. Shoot some foulers first to warm the barrel up then shoot the test batch with just a few seconds between each shot to allow some air through the bore. You need the rifle to be as much the same as possible for every round. You don't want the barrel to get overly hot, but consistently warm.

[marksman]

yes that would be a mistake to clean while testing as you are trying to gauge the performance as the barrel gets some fouling so as to see what it will be doing while fouling and usually 3 shots at a time will put heat into the barrel but not any more than you will encounter hunting, you also get more of a round robin as you don't start and finish at the same load eg: 3-6-9-12-15 if you have 5 test loads x 3, I usually do 5 shots in the mid range for the test first to put some fouling in and to sight for centre bull.
when doing the testing this way I have found the 20 shots are easily done in around 2-2.5 hours and I'm finished by 9am before any wind or heat comes, either the recipe works or it doesn't, I have found that further testing to try and squeeze every bit of accuracy out of the load is normally not worth it,
if its not good enough big changes such as bullet and try again

[straightshooter]

Without an understanding of statistics and in particular 'sample size' and 'randomness' a shooter may be condemned to chasing his tail forever in circumstances where his rifle is of only average commercial accuracy.
Occasionally such a rifle will shoot a very tight 3 shot or 5 shot group and the owner will be pleased that he has a wonderfully accurate rifle. Other groups may be larger and may have a group center in a different position to the 'magic' group.
At other other times there may be a number of 'magic' groups but with group centers in different places.
This effect seemed to bamboozle one of Australia's best known gun guru writers for a long time.
If you really want to assess the true accuracy of your 'shooting system' that is rifle, scope, ammunition and shooter then you need to shoot groups that will provide a meaningful indicator.
For example some years ago when Norma launched their 'diamond line' of ammunition intended for use in ISSF 300 meter shooting (don't know what that is - then look it up) their demonstrations consisted of 60 shot groups.

[sungazer]

I have read the above somewhere else.

[Gamerancher]

Yeah, sort of the point I was trying to make. One "pearler" group is not a true indication of the inherent accuracy of the rifle or load. ( or shooter )
Just for $hits and giggles, go out and shoot an entire box of 50 .22 rounds that you believe are the most accurate in your rifles that group "sub-M.O.A".
Shoot them all at the same target and at the end of that exercise you will have some indication of the "true" group size.

[bladeracer]

Yeah, sort of the point I was trying to make. One "pearler" group is not a true indication of the inherent accuracy of the rifle or load. ( or shooter )
Just for $hits and giggles, go out and shoot an entire box of 50 .22 rounds that you believe are the most accurate in your rifles that group "sub-M.O.A".
Shoot them all at the same target and at the end of that exercise you will have some indication of the "true" group size.

Yep, that's why I prefer ten-shot groups when testing ammo.

[marksman]

yes you need to validate your test after you do an ocw, I have met many people who brag about a group there rifle shot once,
I had one RO at little river once chase me around to show me how he had shot 2 bullets that touched thinking I would be impressed
I like to verify by doing 3 shot groups into 5 targets to verify after initial tests, from here I will establish what I think the rifle is capable of,
if the groups average the same I'm happy with that, just because you get 1x one hole group does not make your rifle a one hole shooter
but I have found if your rifle is a shooter it will shoot most things well
I do not like shooting my barrels out on paper I don't like the taste, I don't shoot comp I hunt, nothing against those who shoot comp

ps, I should say that I don't do a lot of paper punching as I want to preserve the accuracy of my rifles

[Gamerancher]

Considering it takes thousands of rounds to "shoot a barrel out", I don't reckon ol'mate is going to loose any accuracy by actually finding out just how accurate his rifle is.
My suggestion to go shoot a box of 50 was in relation to .22 rimfire, that takes 10's of thousands to even look like taking away the accuracy in one of those.
Also, just because someone shoots competition don't mean they don't hunt as well. I've shot many 1000's of rounds downing critters over the years . Lot of supposition going on there bloke.

[bladeracer]

I actually thinking of doing as you suggested with the 50 rimfire shots. But is one hole better than 5 targets of 10 shots? should you cut out a whole in the middle to shoot through as when you shoot a lot of bullets into the same whole you do get a bit of ripping. Anyway good practice no matter how its done.

To Tarakai I would pick one and then just work with it. In my 243 I shoot a range of different bullets. I do all I can in the reloading room to produce consistent ammo that is the biggest factor in accuracy. The 243 does have a much shorter barrel life so think about how you want to spend it. IMHO between 1500-to max 3000 if you load right down, more likely 1000-1500 with loads in the higher end.

One thing to keep in mind when shooting groups, adjust your sight so the bullets are not hitting what you're aiming at. You don't want your aiming point to be changing shape and size as you shoot the group. And a smaller target is often better than a larger one - I tend to shoot better groups when I aim at the corner of a piece of tape or the junction of two lines instead of the target dot.

I think you are way underestimating barrel life. In the .243 loading hot I would think 1500rds is easy, and 3000rds is probably more realistic. If you back off from max velocities it should last much longer. But if you shoot one continuous session running the barrel as hot as possible it might go off within just a few hundred rounds.

[marksman]

Considering it takes thousands of rounds to "shoot a barrel out", I don't reckon ol'mate is going to loose any accuracy by actually finding out just how accurate his rifle is.
My suggestion to go shoot a box of 50 was in relation to .22 rimfire, that takes 10's of thousands to even look like taking away the accuracy in one of those.
Also, just because someone shoots competition don't mean they don't hunt as well. I've shot many 1000's of rounds downing critters over the years . Lot of supposition going on there bloke.

very sorry if I got your blood pressure up Gamerancher,
my response wasn't at all directed at you it was put up just after what you had posted but came from others writing

when talking about accuracy or flogged out barrels, each individual will be talking about what is acceptable to them
I have rifles of very differing levels of accuracy and some will only be good for maybe less than 1000 rounds till starting to throw flyers
but these are really only going to give there best for maybe 500 rounds so as in my answer I don't waste them on paper as I am a hunter not a target shooter
I did say nothing against comp shooters and I meant it, this is the accuracy I am talking about that will not be there after 1000 shots and maybe not after 500

the average for this rifle is just slightly larger than what you see, shot at 120 yards, I wish all my rifles were this accurate but there not
so again I apologise if you thought I was having a shot at what you had posted

[bladeracer]

very sorry if I got your blood pressure up Gamerancher,
my response wasn't at all directed at you it was put up just after what you had posted but came from others writing

when talking about accuracy or flogged out barrels, each individual will be talking about what is acceptable to them
I have rifles of very differing levels of accuracy and some will only be good for maybe less than 1000 rounds till starting to throw flyers
but these are really only going to give there best for maybe 500 rounds so as in my answer I don't waste them on paper as I am a hunter not a target shooter
I did say nothing against comp shooters and I meant it, this is the accuracy I am talking about that will not be there after 1000 shots and maybe not after 500

the average for this rifle is just slightly larger than what you see, shot at 120 yards, I wish all my rifles were this accurate but there not
so again I apologise if you thought I was having a shot at what you had posted

But if you only shoot for hunting, why would you need that level of precision? At what point do you decide the barrel is "shot out"?

[marksman]

this rifle is used for head shooting deer at distance as we eat the whole deer trying for no waste, sort of varmint hunting for bigger game
the barrel is shot out when you cant rely on shooting a golf ball at 250 consistently, maybe used for other shooting after this such as culling roos
I'm lucky to shoot 20-40 shots out of this rifle a year, I play with other rifles

just think of the old days when foxes were worth money, a 17 barrel a year, usually 1000 shots

[Gwion]

Technically that is a precise rifle but you don't have it set up accurately because all three rounds missed the bullseye.

[Gwion]

Re: testing statistical precision of a particular rifle, you get much better data firing 10x 5round groups and seperate target than you will firing all 50 rounds at one target. You'll get an even better statistical indication of true group size (precision) by firing one shot at those 10 target sequentially, five times (round robin style so you still end up with 5 round groups but with 10 rounds between each shot in each group). You then analyse the groups and average out, then you'll have a pretty accurate indication of what you and you rifle are capable of, precision wise.

I will try to find the paper again but the US military found that there was no statistical advantage in firing 10 shots in a group as 5 shot groups returned the same results as 10 shot groups, however there is a statistical advantage in firing more of those 5 shot groups, as in the example above, ie: 10x5shot rather than 5x10shots to give a true indication of a guns precision and zero for the purposes of finding that guns zero or sighting for a given range/distance.

[marksman]

Technically that is a precise rifle but you don't have it set up accurately because all three rounds missed the bullseye.

it is precise and accurate now

[Gamerancher]

"Marksman", I didn't take your remark personally. I don't shoot paper much myself.
BUT, It did have a tone of "I'm better than that" about it. Perhaps read your posts aloud to yourself before submitting?
I have been guilty myself of conveying the wrong "tone" in a post than what was meant. ( Probably more than once )
Each to his own I reckon, but don't go putting $hit one one group of shooters because you " do not like shooting my barrels out on paper I don't like the taste".
That's a bit like saying "I'm not racist but...."

With regards basic statistics, the larger the test sample, the more true the result.
Example, conducting a poll of 1000 people who walk past in Martin Place about whether we need to "toughen" the gun laws is not a true indication of the opinion of all Australians.

I still challenge anyone to try the 50 shot .22 challenge, yes adjust your sight so that the group is away from your aiming point, and come back and show us your "sub M.O.A" group. Just sayin'.

[marksman]

good to hear you didn't take anything personally Gamerancher
just saying though, what I said was tongue in cheek but I really don't like the taste of paper

[Stix]

Considering it takes thousands of rounds to "shoot a barrel out", I don't reckon ol'mate is going to loose any accuracy by actually finding out just how accurate his rifle is.
My suggestion to go shoot a box of 50 was in relation to .22 rimfire, that takes 10's of thousands to even look like taking away the accuracy in one of those.
Also, just because someone shoots competition don't mean they don't hunt as well. I've shot many 1000's of rounds downing critters over the years . Lot of supposition going on there bloke.

very sorry if I got your blood pressure up Gamerancher,
my response wasn't at all directed at you it was put up just after what you had posted but came from others writing

when talking about accuracy or flogged out barrels, each individual will be talking about what is acceptable to them
I have rifles of very differing levels of accuracy and some will only be good for maybe less than 1000 rounds till starting to throw flyers
but these are really only going to give there best for maybe 500 rounds so as in my answer I don't waste them on paper as I am a hunter not a target shooter
I did say nothing against comp shooters and I meant it, this is the accuracy I am talking about that will not be there after 1000 shots and maybe not after 500

the average for this rifle is just slightly larger than what you see, shot at 120 yards, I wish all my rifles were this accurate but there not
so again I apologise if you thought I was having a shot at what you had posted

Can i ask...do u get this accuracy from tweaked off the shelf production rifles, or custom builds/custom rebsrrels...?

[marksman]

both, but this one is a customised whitworth mauser 98
I like mausers here is a 650 yard shot