I have been thinking about this for a while and haven't really come up with a good possible explanation.

Let explain a scenario to illustrate:

Rifle: Model 70 Laminate. 300 WSM
Load: 61 grains Varget, 150 gr Hornady SST
Range conditions: Sunny, light breeze, temp 70-80

After working up to this load, it showed the most promise, but still puzzles me a bit. First group while working up loads indicated it was a load to take a little more time on. Went home and loaded some more to test further.

Subsequent groups wereall 3 shot 100 yard)
2 groups @ approx. 3/8" each. Excellent in my mind. (Day 1)
Then two more groups that were 1 1/8" and 1 1/4". (Day 2)
Then 2 more groups that were 3/8" and 1 1/4". (Day 3)

These averaged out to right at 3/4". All groups are acceptable for a hunting rifle, but just not the consistancy I want. I'm fine with a 3/4" average rifle, but am wondering why I get half the groups at 3/8", then the other half basically at 1 1/4"

The bore was clean while starting, but not squeaky clean. I did not clean while shooting these loads. Other loads through the rifle indicate that the rifle likes a lightly to moderatly fouled bore....more than four or five shots, but less than 40 shots...

Could it be that maybe one day I was doing better than the other day or that it was "just the day"?

Additionally, I have found the chamber to be slightly out of round and must full length size to be able to chamber flawlessly. I am thinking that this is probably the main reason to the inconsistancy.

Maybe I should't worry about it, as I am planning on abandoning this load and begin working on a Partition load so I can go after elk with this rifle, too... My plans have changed after I started on this load.

What are your thoughts? Thanks!

What you are seeing is nothing more than the normal group distribution from shooting 3 shot groups. If you shot 10 shot groups, you would see occasional 3 shot groups that were very small, included in the larger 10 shot grouping. The real group size is more like 1&1/4 inches to 1 & 1/2 inches.

Winchester beds some of their stock with what could be described as bathtub calk. Maybe its heat glue, I don't know, but many times you have to rebed them to get them to shoot.

I really have no experience with the .300 WSM and Varget. Isn't Varget a little fast for that caliber?

Geo.

Spend a little time bedding that rifle and you'll probably get more consistent grouping in the 3/4" range or so. It also sounds like your bench technique might be slipping a bit, if you're doing everything else right- letting the barrel cool between groups, loading properly and weighing charges accurately, etc...-

Geo. hit it bang on.

I haven't run the stats for three shot groups, which are terribly weak statistically, but for five shot groups, 95% of your groups will naturally fall between 1/2" and 1 1/2" (assuming a true 1 moa gun) just due to normal random variation. Stated another way, if your gun's long term average group is 1", five shot groups as small as 1/2" or as large as 1 1/2" do not indicate any change in accuracy.

So the guy that shoots a 1/2" five shot group with one load, and then shoots a 1 1/2" group with another load, and decides that the second load is not as good, has made a decision based on random noise. They are actually statistically indistinguishable.

Which is why I sold my 300 WSM Coyote. It wasn't consistent no matter what I tried.

denton - i was about to tear into your post until I read it a third time. I agree with your thoughts based off one group.

However, if I shot three/ 5 shot groups that print 1/2" and 3/5 shot groups that print 1 1/2" - guess which load I'm going to pick!

Personally I'd have to take a close look at bench technique and to positioning on the bag. Or at least that would be a good place to start.

Lighting conditions have also come into play a bit for me as I age-also the type of target I use with the light conditions seems to make a difference.

And then there is our old friend mirage.

I'd take a close look at this type of stuff-as well as bedding. But personally I suspect something besides the bedding.

"GET TO THE HILL"

Dog

Just a thought, are all of your cases of the same brand?

Trapdoor - I may have missed it, but is this rig scoped or open sights?

So the bench technique response doesn't become the proverbial bandwagon, let's take and throw it out the door for the time being. I am very conscience of technique and bag placement when I am at the bench. Not that I am saying it doesn't happen, just that it already occurred to me, and knowing myself, I can assuredly rule it out. I am confident that it is something else...if anything.

All cases are same brand/same lot. Same as powder, bullets, and primers. Powder charges are individually weighed. Cases/bullets are not segregated into "like weight" groups...As it is not a benchrest rifle, but a hunting rifle, I feel this segregation is a tad too much. I do not have a run-out indicator, and frankly do not want to go to an extreme for a hunting rifle.

Rifle is scoped with a Leupold Vari-X III, 4.5-14 AO. Yeah, I know its too much for a big game rifle, but it's all I have...and had to take it off another rifle at that...

The thought that the groups are all part of the normal group distrubution makes some since and maybe I can live with that theory. However, whether the rifle/load combo is 3/4", or 1", or 1 1/4" combo isn't my biggest concern. All these are basically fine with me, as long as they are consistantly that. I would rather have a consistant 1 1/4"er than one that gives me a 3/8" then a 2", then a 3/8" again...

Bedding has occured to me. I do want to have the rifle properly bedded, but I lack the knowledge to do it myself, and don't have a gunsmith close by, that I am aware of.

[ 06-27-2003, 22:51: Message edited by: Trapdoor ]

T/C....

Three five-shot groups are MUCH better than one five-shot, which is, in turn much better than a single three-shot. I'd probably feel reasonably comfortable making the same choice you indicate.

Still, tests of one level of variation vs. another are notoriously weak, mathematically. The practical outcome of all this is that, until you have at least 5 or 6 five-shot groups, you don't have much idea of how accurate your gun is. One three-shot group will routinely mislead you.

Trapdoor -- You may have hit upon your problem, the bedding. Until a good gunsmith tell you he sees no problems, you may be reaching for the impossible. ----- I, by the way, really like your scope, don't let anyone talk you out of it, just because is is too big. I love small groups, as does everyone. You mentioned discounting technique for the moment. Just one thing about technique, eye position at the scope is very important to me when I shoot. Are you positioning you eye at the same place each and every shot. I have to ask myself this often, and then do it consistently. I cannot drink caffiene or beer and shoot well for groups. Some days I have that touch and the old Crosshair is steady as a rock and the group is minute, on others it wavers and try as I might the group is only average at best, and with my favorite loads.------ Aside from the gunsmithing and the eye position, I can't really offer anything else to try. Good luck and good shooting.

Trapdoor...

The statement you cite is simply a general statistical truth, which does happen to apply to your situation.

The rule is that if the variation you are seeing can be easily explained just by random chance, there is no reason to look further for an explanation.

Group to group size differences of the size you are seeing are completely within normal random sampling error when nothing is changing in your gun or your load. They are completely explainable just by virtue of the fact it is impractical to shoot many hundreds of rounds to establish your variation, and you are essentially taking three-shot samples. Three-shot samples are very weak statistically, and give a poor estimate of what will happen in the long term.

You can check bedding and all that if you want, but, from what you've posted, there is no evidence that anything in your gun or load is changing.

Without getting too deeply into math here, 6 groups is still not much upon which to make any decisions...particularly if 3 are 1/2" and 3 are 1-1/2".

As you likely know, it is entirely possible to throw dice so that the same number comes up several times in a row. Likewise, with a given load it is entirely possible to shoot three good groups in a row and three bad groups in a row.

While it is true that choosing the three good groups load is somewhat more likely to give you the better long term results, it most certainly can't be done with a high confidence level that those three groups represent the typical accuracy of that load.

A lot of good loads have been tossed away based on "bad" performance of just a few groups.

Another thought is this. If you are shooting groups without wind flags, then you are wasting your time when you get to the sub-MOA level of accuracy. If you don't have and learn how to read windflags, then you have no way of knowing where each bullet "should have" gone. Wind will move a 747 and it certainly will move ANY bullet at ANY velocity. If the wind varies between two shots, but the two bullet holes touch, what have you learned? I can assure you that you have NOT learned that "the wind doesn't bother this load".

I'd suggest that you relate your rifle's accuracy to the accuracy you need. If you are going to hunt elk, you need a rifle which will keep all it's shots in about 8 inches at 300 yards...that's about 2.6 MOA, with you shooting it. If it averages less than that over say 6 or 8 weekends, then you'l spend your time more productively learning to shoot offhand and from other field positions than from trying to improve the accuracy of your rifle.

Good luck, and have fun with that rifle. There are a lot fewer true 3/4 MOA rifles out there than we're led to believe.

AC

[ 06-28-2003, 03:01: Message edited by: Alberta Canuck ]

If you shot the groups on the same day I'd think about bedding-and it still could be that -but personally me thinks not. If it is beddding how does it happen that you shoot some lil bug holes 2/3 of the time?

It has to do with something else I'd be for betting--I know you guys don't see it-but it is crystal clear to me--grins........

Anyway let us know what you find out.

How old are you? What type of light and wind condtitions were you in each day? Also the time of day?

"GET TO THE HILL"

Dog

Did you use the same kind of target each time? What do you use for a front bag and for a rear bag?

[ 06-28-2003, 04:19: Message edited by: Mark R Dobrenski ]

Your average is about 0.85" for the 6 groups, which I would consider good enough in any big game rifle.

I believe you are seeing normal statistical variation with maybe a little human factor, who knows what that could be? I know I can get that much variation just from anything over half a cup of coffee.

John

I would say that your 300 WSM is shooting pretty good. I got one too. Same problem, an over size chamber or somthing, Fired cases a tad out of round. My rifle is at the smiths, piller bedding and a Krieger barrel will fix it. My rifle shot well enough for me to kill a couple of head of game. I put a fixed 4x on mine. I shot nothing but 180 gr. Bullets in mine. RL-22 and 25 seems to work very well, 180 gr Northfork was turning in pretty good groups, since the bedding and barrel was not right and right at 3000 fps. I have only been shooting the Northfork for a year. I like it a lot.

A friend of mine had something like that happen with his 338. It would put 2 shots right next to each other and then throw one an inch or two off in a random direction. His barrel was mostly free-floated and he put a piece of cured RTV under the barrel at the tip of the forearm to give the barrel some tension at the tip (pressure bedding I think its called). I think he had to pull the forearm down a little and slide it in. After that it consistently turns in groups of 1/2" to 3/4" with no stringers. It sounded relatively easy to do and shouldn't take too long. It might be worth a try before shipping it off to a 'smith.

This is why it pays to quit once you've shot one good group at the velocity you want. Load like that for ever and make sure your check zero is with just one shot.

Random variation is often not terribly random. Lots of it can be chased down to causes.

Here, first I would blame the wind. 10 mph drifts about .7" at 100. Switchy winds 5 left, 5 right will do the same thing. Get some windflags......

Second, since this is between days, did you take the gun out of the action to clean?

Did you load all rounds the same day? Sometimes scales get reset, primers get seated deeper or shallower, cases get lubed more or less, dies get turned in a little more or less. Sometimes shellholders get changed.

Does your ammo box fit very closely? I've heard of ammo boxes pushing bullets out of round, with all expected consequences.

Ammo temperatures? Did the ammo get put away differently on the second day? Did you feed from the magazine on the second day, and not the others?(concentricity problems).

Or, in other words, any of the "75 common accuracy gremlins". HTH, Dutch.

Trapdoor--After having read the replies in some haste, I would submit the following.

The people that are asking about shooting technique are quite right in doing so. After shooting for the better part of a half-century, I can state with certainty that practice and attention to detail is warranted. Even get yourself a coach to watch you, spot for you, and talk with you about it. At least for me, I continually need to pay attention. It works great if you have a shooting buddy, as both of you can learn from the process.

Not too long ago, I bought a Winchester M70 Super Grade in .30-'06. I didn't have a .30-'06 and didn't have any M70's. Now I do. It will shoot about 1 & 1/4 inch groups with pretty much any load. Have yet to improve on that, though. Take a look at that bunch of goop under the recoil lug that Winchester beds them with. Ugh!

By the way, what part of WY are you in?

Geo.

Two 3/8" groups at any time would indicate to me
what the shooter and the rifle are capable of on
any given day. In most hunting situations the first round's POI determines success. Most of us are not going to get more than 3 shots at any game
but I still shoot 5-7 round groups to look for inconsistencies in shooting technique and reloads.
I would try 5 round groups at various ranges under
varrying conditions to build confidence! If I was
shooting paper for competition I would probably
invest in a more accurate rifle but for Elk and
deer sized game 3/8 - 1.5" groups at 100yds is a
good starting point for most sporter barrells. I
have the same scope on a 7mm rem mag and don't
need a spotting scope out to 200 yards. Sounds to
me like you only need more range time. Hang in there! BLR7

If they were my loads I would run them across a chrony and check the standard deviation. My guess is that your on to a good load but need a tweak or two in the right spot, the trick is finding the right spot. Primer, brass, trigger, bad day at the office. Welcome to the wonderfull world of troubleshooting.