Damn this gun is frustrating. I can put the first two shots from a cool barrel within 0.25-0.40 inches but that third shot is going to be within a 1.5-2.0 inch radius without any constistent direction. But, it is a hunting rifle, so maybe I shouldn't be that concerned with the third shot.

without knowing more i'd say you have a bedding problem with the barrel hitting the stock as it warms up

Shoot two shot groups and be happy.

If the first two shots go to the point of aim, you can always walk up to the animal laying DRT, put the muzzle right up against him wherever you want the third shot to be, and pull the trigger.

I think it is a bedding problem. The rifle is nothing fancy. Just a standard Ruger M77 in 300 Win Mag. With the Ruger's being pressure bedding on the front, I'm sure this is what is causing the problem.

Can't really say if it's bedding or ?. I can only offer a similarly related experience .

In my case Bullet choice combined with barrel harmonics required " Pressuring " the barrel at a specific spot !.

Action was fully bedded floated barrel and it didn't work out as I had hoped it would . So by placing a semi

soft cushion in various spots along the barrel channel , I eventually found a sweet spot .

I then made a permanent epoxy ridge with just a touch of pressure when action was fully snugged down .

Made my groups of #5 half the CTC distances than previously were achievable .

Floating isn't always the answer ,least wise in my particular case .

I was under the mis belief full bedding floating barrel was ultimate accuracy in every case . Learn something

new all the time . I asked one of our highly respected Resident GunSmiths and it was his suggestion to try it .


I'm VERY GRATEFUL that I took his advice !!!.

Group Size Statistical Analysis has been greatly studied and turned into a science. The below is from one of the papers on the subject which used a scientific method to reach a conclusion on the number of shots in a string and the number of strings in an aggregate for the final proofing of a load/rifle to determine a valid measurement of accuracy. At first blush it looks like a bunch of mumbo jumbo, but in reality, it is the basis from which using an aggregate of 5 shot strings was established as a valid benchmark, and whereas using a mere 3 shot string was shown as not being valid in proofing accuracy. When using three shot groups to determine the actual accuracy, the study resulted in an observed 0.863” average group size for a one MOA proof rifle. It was further determined that these three shot group measurements would need to be multiplied by a factor of 1.158 to show the true accuracy of the rifle. This is a major reason why you find so many people posting targets on the internet proclaiming that their factory rifles are shooting under .5MOA with factory ammo when in reality such accuracy is impossible even when testing the ammo through proof barrels. This is also a reason why people often chase their tales in circles trying to keep up with that “third round flyer” as the particular rifle/ammo combination is in reality not as accurate as the 2-shot group makes it appear.

Give it a read, and when you get a chance, test your rifle with an aggregate of four 5-shot strings. This will give you an indication of where you stand. The measured accuracy IS WHAT IT IS, and reducing shots from the string and/or throwing out flyers WILL NOT CHANGE what it is in reality. Also, shooting half-MOA groups in the field with a hunting rifle is not reality. A good rifleman can harvest truck loads of game using a vetted 3-MOA rifle. If your rifle is a stock Ruger, it may or may not respond to a reduction in the barrel pressure point. In addition, you may be experiencing binding in the action with the mag box and the middle screw acting like a fulcrum.

Group Size Statistical Analysis:

“A Matlab program was written that simulated 100000 shots from a rifle, with a one MOA double sided standard deviation of cone angle, at a target 100 yards away. The simulation then formed as many groups of N shots as it could from the total of 100000, and calculated and recorded the largest center-to-center distance of each group of N. N ranged from 2 to 20 shots. It then averaged all the group sizes recorded for each N, resulting in the average group size for a N shot group. For example, given 100000 shots, there were 5000 groups of 20 shots. This resulted in 5000 group size measurements, and one average group size value for a 20 shot group.

Figure 5 shows a simulated target after 250 shots. The rings are spaced 0.5 inches apart. Notice that most of the shots fall within a one inch circle, but there are only a few that are more than one inch away from the mean POI. In fact, the center regions of the target are hit most frequently, and with far fewer hits at the edges of the target.

A histogram showing the distribution of the shot impact locations for the above conditions is very interesting and is shown in Figure 6. The spike shows clearly that a shot is most likely to land in the center, with shots far away from the center occurring much less frequently. This result shows clearly that one could shoot two or more three shot groups with a small (say 0.5”) group size, then have another 3 shot group exhibit two shots very close to each other with a third shot landing an inch or more away. The distribution shows only the probability of a single shot falling at a point away from center, not the probability of a group of shots falling at a particular distance. This explains why one may see unexplained “flyers” out of a good shooting rifle. These are not true “flyers” in the sense that some process other than the normally distributed angle deviation caused them to diverge significantly, such as a damaged crown or an unbalanced bullet, but are the result of the characteristics of the shot angular distribution itself.

By intuition, it is obvious that a total aggregate of three shots is clearly not a large enough sample size to accurately determine the true distribution of a rifle and load. The lesson here is to shoot many shots, usually in multiple groups of five, and average these to get the aggregate. Just how many shots are needed to form an accurate estimate requires a deeper mathematical analysis of the underlying statistical model, and will be the subject of a future paper.

Based on these conclusions, the author uses 4 groups of five shots for the final proofing of a load.”

I have two local gunsmiths and both do a lot of benchrest shooting. They both have told me in the past that if the gun puts two together and the third round out, it's a bedding issue. That's an easy and inexpensive place to start.

the action screws are loose?
torque to about45 inch pounds.

quote:

Originally posted by hivelosity:
the action screws are loose?
torque to about45 inch pounds.

I thought the same, but let the rifle cool back down to complete cool and it will do the same thing again. If it were loose screw, it shouldn't do that.

Same rifle same load, different deating depth as the above picture. The seating depth on the above is 2.728 based off the ogive.

This seating depth was at 2.828, which is the longest I can get into the magazine with sufficient clearance within the magazine.

Make sure the barreled action is sitting square in the factory inlet and torque the angle screw 35 in-lbs, the rear screw 25 in-lbs, and the center screw 15 in-lbs. If you have a poor fit, this is about as tight as you can go without binding the action over the mag box. When torquing the center screw, make sure your mag box maintains proper clearance so that it does not lock up. I've handled quite a number of Rugers that were erratic due to this binding and would respond well when torqued as described above. If the stock fit and bedding were perfect, you could run the torque right up to Ruger recommended specs, but many will bind out of the box.

As to the forend pressure pad, most all custom match barrels will respond well to free floating as long as you have the correct length pad in front of the action. But on a mass produced factory barrel, not all will respond as well and at times will have a greater consistency with an added forend pressure point. There is an old trick where you shim the angled recoil lug to change the angle in the stock to temporarily reduce or eliminate the factory pressure point while torquing to the previous noted specs. This is done as a test to see if the barrel responds well to having the pressure point either completely removed or lightened.

Hope this Helps.

does it have a laminated stock?

Scope tight? Good rest in the bags? Solid bench from which to shoot? Relaxed before you began to shoot? Sun in your eyes? Heat swirls out at the target? Breezy?

quote:

Originally posted by hivelosity:
does it have a laminated stock?

Yes

quote:

Originally posted by homebrewer:
Scope tight? Good rest in the bags? Solid bench from which to shoot? Relaxed before you began to shoot? Sun in your eyes? Heat swirls out at the target? Breezy?

Tight scope.

Good rest in bags

Solid bench

Using good shooting form

No sun problems

No heat because shooting early morning

quote:

Originally posted by graybird:

quote:

Originally posted by hivelosity:
the action screws are loose?
torque to about45 inch pounds.

I thought the same, but let the rifle cool back down to complete cool and it will do the same thing again. If it were loose screw, it shouldn't do that.

If the barrel bedding were the culprit I would suspect the group would climb rather than descend as the barrel heated and the taper forced the muzzle up. I'm going to guess this phenomena may be due to chamber heating. It is not uncommon for groups from hot loads to strike lower than lighter ones due to decreased bore time in recoil. As you fire your groups, could an increasingly hotter chamber raise internal cartridge case temps that, in turn, raise chamber pressure and velocity enough to change impact? This would be especially true if you take extra time with that third shot trying to get a tight group. If you have access to a chronograph, perhaps you could record velocities and correlate to impact points. Another possibility may be that as the chamber heats it is changing the way the threads mesh in the receiver and causing a shift in impact. Either issue would resolve when the rifle cools off.

Every gun I own shoots two tight and one flyer. Just that on some the third flyer is within a 1/2" or less of the other two. All of them are bedded and floated except one, and I have a mixture of Winchesters, Remingtons, a Tikka, a CZ (not floated). They ALL do it! Just to varying degrees. Had a custom Hart barrel. It did it. Just got a custom Krieger barrel and it does the same thing. I have a 7X57 in a M-700 Mountain Rifle. I finally gave up on tight 3 shot groups and now only shoot 2 shot groups with it. They are under 1" at 200 yards with a 2 shot group. 3 to 3-1/2" with a 3 shot group. Good enough with the 2 shots. None are bench rest guns and only two have medium bull barrels.

Bobster,

Interesting comments. I have shot these loads over the chrony. The third shot is always faster than the first two. I'll need to dig up my notes, but I know it is faster.

One thing that I'm not happy with is the velocities I'm getting with this load. I'm about 150 fps slower than what I thought I'd be getting. But the barrel is only 24" and the test barrel in the Barnes book was a 26" so I wrote it off to differences in my rifle and the test rifle Barnes used. I also noticed was that the deeper I set the bullet the slower the velocity got. I basically lost about 50 fps going from the 2.828 seating depth to the 2.728 seating depth. But, I figure an elk or kudu isn't really gonna notice that 50 fps or even 150 for that matter.

quote:

Originally posted by Rae59:
Every gun I own shoots two tight and one flyer. Just that on some the third flyer is within a 1/2" or less of the other two. All of them are bedded and floated except one, and I have a mixture of Winchesters, Remingtons, a Tikka, a CZ (not floated). They ALL do it! Just to varying degrees. Had a custom Hart barrel. It did it. Just got a custom Krieger barrel and it does the same thing. I have a 7X57 in a M-700 Mountain Rifle. I finally gave up on tight 3 shot groups and now only shoot 2 shot groups with it. They are under 1" at 200 yards with a 2 shot group. 3 to 3-1/2" with a 3 shot group. Good enough with the 2 shots. None are bench rest guns and only two have medium bull barrels.

Rae,

I'm starting to follow this line of thinking myself. I am going to load up 10 rounds and shoot 5 - 2 shot groups at the same target with the barrel cooling down completely between each of the 2 shot groups.

I hope this will also tell me something. I should get them knocked out this weekend.

quote:

Originally posted by graybird:
Bobster,

Interesting comments. I have shot these loads over the chrony. The third shot is always faster than the first two. I'll need to dig up my notes, but I know it is faster.

One thing that I'm not happy with is the velocities I'm getting with this load. I'm about 150 fps slower than what I thought I'd be getting. But the barrel is only 24" and the test barrel in the Barnes book was a 26" so I wrote it off to differences in my rifle and the test rifle Barnes used. I also noticed was that the deeper I set the bullet the slower the velocity got. I basically lost about 50 fps going from the 2.828 seating depth to the 2.728 seating depth. But, I figure an elk or kudu isn't really gonna notice that 50 fps or even 150 for that matter.

Check out this article: http://findarticles.com/p/arti...36/?tag=content;col1

The author advocates 20 minute cool downs for hunting rifles between shots to assure every round goes out a cold tube. Alternately, he advises shooting a quick 3 shot group before the barrel gets heat saturated. Some interesting comments about erratic accuracy during a barrel's warm up period until it reaches an equilibrium.

quote:

Can you tell which is the third shot...

IME, consitantly having two tight and then opening up indicates the barrel is over heating. No bedding change will fix that.

Greybird, I've fixed this problem on more then one occasion by varying the oal. Starting at magazine length, and coming in at .005 increments. Some rifles can be very picky about their oal.

As mentioned in previous posts, there are other things to check.
1. Action screws.
2. Free floated barrel
3. Bedding.
4. Maybe this just isn't "the load" for this rifle?

I can't give you a long statistical scientific expanation, but I've had many rugers come in with accuracy problems and I have solved most of them with free floating and bedding. Of course, "solved" means closing the groups up to acceptable 3 shot groups, but does not always solve the third shot "flyer". As someone said, a flyer may be .25 of an inch or 1.5 of and inch. Most of the time, some proper bedding and free floating will get these guns to MOA accuracy on 3 shot groups.

By the third shot on a rapidly fired group in a magnum caliber, you will certianly have some heat and you will probably had a slightyly differant point of impact, but if you can control the harmonics better, you will reduce the differance significantly. I have also done some stress relieving of the barrels in guns that has given me good results. Hammer forged barrels are often full of stress points which get worse when the gun heats up.

You have normal accuracy from the average hunting rifle. I would expect better accuracy from small bores, 222, 223 , 22-250, 204. Its all in the barrel.

quote:

Originally posted by graybird:
Rae,

I'm starting to follow this line of thinking myself. I am going to load up 10 rounds and shoot 5 - 2 shot groups at the same target with the barrel cooling down completely between each of the 2 shot groups.

I hope this will also tell me something. I should get them knocked out this weekend.

Graybird,
Personally I would shoot two quick consecutive shots to immulate an actual in the field situation. I shoot in 90 degree plus heat and even my rifle barrels don't heat up that bad on a quick second shot except on my 7X57 Remington Mountain rifle. That barrel is so thin (coach whip barrel) that it feels like it is ready to "melt" after the first shot in 98 degree heat. But even it, tends to shoot good until the third shot which opens up badly.
I failed to mention that on two of my better/best shooters, M-70 Coyotes, the actions are not bedded and have only floated barrels.
One other thing you may want to try is re-installing a pressure point on the barrel in the forearm. I know a gentleman who has had good results on a "few" rifles with this. Not all but a few.

quote:

Originally posted by graybird:

quote:

Originally posted by hivelosity:
the action screws are loose?
torque to about45 inch pounds.

I thought the same, but let the rifle cool back down to complete cool and it will do the same thing again. If it were loose screw, it shouldn't do that.

I would be tempted to give it ago when the barrel is hot.

quote:

Originally posted by butchloc:
without knowing more i'd say you have a bedding problem with the barrel hitting the stock as it warms up

I agree.