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Discussion Starter #1
A Remington factory tech told me that the 2 1/2" inch groups out of my 300 RUM at 100 yards could still be 2 1/2" groups at 500 yards and that the bullets out of the 300 Ultra didn't stabilize until they were way down range, like beyond 300 yards, so I shouldn't expect to get this gun to group well at 100 yards, but to shoot my groups at 500 yards and see what I get.....

Does this really make sense or was this guy feeding me a line of bs?

thanks,

E
 

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While it is sometimes true that long range groups are actually smaller in terms of minutes of angle than shorter range groups in some rifles and some loads, it is very rare.

And it would never be such that a 2 1/2 inch rifle at 100 yards will be 2 1/2 at 500 yards.

It's a line if poo.
 

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He's describing a real phenomenon, but likely overemphasizing it to make excuses for poor accuracy in the rifle. I have often seen rifles that wouldd shoot the same group size at 100 and 200 yards. In fact, I own a Spanish Mauser .308 "Scout-style" carbine I made that shoots a 3-shot, 2.5 inch group at 100, 200, or 300 yards. Different elevations, of course, but the group size remains consistent. Sometimes in some loads in some rifles the bullet settles in, or "goes to sleep", very consistently in its flight, and that's what you'll get.
 

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This phenomenon is not rare by any means when shooting long bullets in fast-twist barrels. I have seen it in my M700VLS in .260 Rem when firing 142 HPMKs out to 600 yards. 1.2 moa at 100 yards, 0.8 moa at 600....in still air of course. I am not the greatest wind doper..... :eek:



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Just remember that 1.2 MOA at 100 yards is about (if you let one MOA =1.0471975511966 in. rounded off to 1.05) about a 1.26 inch group. At 600 yards the 0.8 MOA group is about 5.04 inches. The gun groups smaller in terms of MOA at any distance, but the actual groups get bigger because one MOA gets bigger with distance.

I think there would be very, very few rifles that shot 2.5 inches at 100 yeards that would shoot the same sized group at 500 yards.
 

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Haven't had one that would shoot identical groups at 100 and then at 300yds., but have had a few that would shoot smaller in terms of MOA from 100 to 300 yards (like 1.5" at 100, but only 2.5" at 300 for 5 5-shot groups at each range). Usually it's a very long bullet in a fast twist barrel (in my case, 140gr. HPBT 6.5mm).

Much more common is for a bullet to shoot WORSE than expected (like 1,5MOA t 100 and then 7" at 300yards)
 

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It sounds like you have a problem with your rifle. It should be able to produce better accuracy than that. If you feel confident it wasn't the shooter then I'd recommend taking it in for warranty repair.
 

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Elkstalker; If you intend to use the gun at those ranges, and you have a place to shoot 500 yards, I would definately give it a shot, but, remember, for most folks the margin of (human) error increases as the distance increases. You will also have to deal with "conditions" that are not noticable at the closer ranges...wind direction changes, scope mirage, etc, If you can "read" the mirage effects in your scope as you move downrange to judge wind direction and speed, your groups and accuracy will be much better. I was a Benchrest competitor for many years, and my problem was always the 100 yard event (I just did not have the eyesight to judge the "conditions" at that range). Once we moved out for the 200 and 300 yard events I could play the conditions much better....just suited my eyesight. Once I was competing in a 300 yard aggregate match (group size scores from 5 targets each at 100, 200, and 300 yards are combined into a grand aggregate score, and that determines the match winner). The conditions we had that day was rain, and gusting/switching tailwinds at 40+ mph. I had a heck of a time at 100 yards...my group average was in the mid to high .300's. When we moved out to 200 yards (where I could read ((see)) the conditions much better), the groups averages were getting better, and stayed in the low .300's. When we finally moved out to 300 yards, my groups were still in the low 300's.........I won the match with a grand aggregate of .3404 for the combination of all of the 100, 200, and 300 yard targets. I guess the point I am trying to make here is: Yes, under the right conditions, a gun can shoot same size groups from 100 yards and beyond, but there are many variables that have to be taken into consideration.
 

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The Troll Whisperer (Moderator)
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Have a Ruger M77 (tang safety) that has been Douglas rebarreled and chambered to 7mm Dakota. Using Hornady Interlock 175 gr flat base soft points, it shoots MOA at 100 yds., 1.25 MOA at 200 yds and at 300 yds, it shoots .75 MOA.

Think the long bullet-for-bore does need some distance to really stabilize. This is the only rifle I have that does this. A 6mm/284 shooting 100 to 105 gr bullets is consistent in group sizes from 100 to 300 yds (the longest distanace at our public shooting range).
 

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The only way I can see this happening is if the scope has a different parallax at 500 vs 100. If a bullet is already off course by 1 1/2" from point of aim(to give a 2 1/2" c-c group) at 100 yds, how can it NOT continue this angular flight path out to 500yds. Don't tell me it "goes to sleep", that only explains the rotation on its axis. The 1 1/2" off path course is an initial lateral "shove from the muzzle" and may not continue as dramatically out to the 500 mark, so you may end up with a 7-8" group out there but a 2 1/2 group at 100 is physically unable to be the same at 500. Unless, as I said, the scope has parallax corrected for a distance like 400 yds and is much greater at 100.
 

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Called putting the bullet to sleep. Shooting M1 Garands with match 308 barrels we used ball ammo with 147 gr bullets out to 300 yards and only then switched to the 178 gr match bullets for 500, 600 and 1000 yards. Bullets had a yaw for the first 200-300 yards and didn't stabilize until after 300. Nothing wrong with your gun its bullet choice.
 

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Discussion Starter #12
So the only way I know of to tell if your bullet has not stabilized is if it punches something other than a perfect hole in the paper. Is there another way to tell?

E
 

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all our bullets -save round balls - are aerodynamically unstable. When inclined, their center of pressure is far ahead of their center of gravity. gyroscopic forces tend to keep the nose pointed in the right direction, but the nose will tend to oscillate, which causes the gyroscopic forces (precession) to push the nose in a direction 90 deg relative to the aerodynamic oscillation. Looked at from the back, the flight path is always a spiral. The remington tech's point seems to be that the farther down range the bullet goes the less the spiral disturbance - or coning angle - becomes. This due to the muzzle jump out of the barrel where the gas flow tends to push on the back of the bullet for a few feet. High trajectory angle firing aka naval guns result in coning angles exceeding 45 deg on the downward leg of their flight. Bullets do not change their pitch angle relative to their position in the trajecotry. If fired at 45 deg they will have that same angle - or worse - on the downward leg of the trajectory.

as long as the firiing angle is kept low, the spiralling will gradually diminish.

Northwoods
 

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I read a book written by a benchrest shooter and he claims that idea that bullets go to sleep out past say 300 yards is BS. I figure these successful benchrest shooters should know what they are talking about as the ones who have been in the profession for any length of time will have shot more rounds then most of us will ever shoot in our lifetime. Sometimes it seems that trying to figure out these loads can be quite maddening and make you want to pull your hair out or take up golf
 

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I agree that benchrest shooters can be a wealth of experience and knowledge. We should keep in mind, though, that BR shooters use relatively mild cartridges for 100 and 200 yard shooting- they know that getting some of the big anti tank cartridges to shoot well is harder than getting mild cartridges like the 6mmPPC to shoot well.
The concept of magnum cartridges shooting as well at 200 as they do at 100 is not new- it's been noticed for a long time.
A rifle shooting 2.5 inch groups at 100 still shooting 2.5's at 500 seems a bit much, though, in my experience.
 

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" Bullets do not change their pitch angle relative to their position in the trajecotry. If fired at 45 deg they will have that same angle - or worse - on the downward leg of the trajectory."

Northwoods[/QUOTE]

I believe that's called 'over'stabilization...i.e. a twist that is too fast for that particular projectile.
 

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The Hog Whisperer (Administrator)
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Correct. For accurate long range shooting, the bullet noses should start to pitch down again. If they don't it costs you quite a bit of drag.

That is the reason twist rates get very critical beyond 600 yards or so. The 100 and 200 yard shooter will never notice this.
 

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This is not overstabilization. A bullet, either spinning or not, is statically unstable, meaning that the center of pressure is out ahead of the the center of gravity. Center of pressure is calculated by dividing the pitching moment by the normal force (generated by the angle of attack), the resulting length is usually expressed in calibers, and is always ahead of the center of gravity with an elongated bullet. Pointed noses, boat tails and supersonic flight makes this dimension even longer. Looking at the force diagram of a spinning bullet in flight, there are no forces, moments, etc. present to cause it tip forward as the angle of attack increases as would happen on the downward leg of flight, regardless of the firing angle. The coning angle will increase. They may even tumble. If it is spinning, and if the nose is disturbed from straight flight - which it always is - the nose is going to move 90 deg from its angle of disturbance. Overstabilization may cause excessive gyroscopic precession beyond what is required to keep the bullet pointed down range. My information comes direct experience with large bore firing tests and wind tunnel experiments, and reviewing tests conducted on naval rifles and howitzers, both of which shoot at very high angles. For those interested, the NACA or NASA web sites may have lots of technical papers in this subject.
 

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The Hog Whisperer (Administrator)
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I'm not sure which side of the argument you are on. Are you stating that it is impossible for a projectile to have the nose change the angle at which is launched, as it goes downrange?
 
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