Why is it that boomers like the RUM or STW cases seem to be range limited to the 3/4 mile or less, and things like the 6.5mm Creedmoor and smaller capacity rounds are a mile-plus?

Recoil.

Marketing.

No cartridge is range limited, just go back in time and ask Billy Dixon.

A fast twist barrel and a VLD bullet in a RUM, STW or a Weatherby will be flatter shooting than a little Creedmoor by a long shot.

Especially the 7mm's they are about perfect for bullet diemeter versus BC.

quote:

Originally posted by Big Wonderful Wyoming:
No cartridge is range limited, just go back in time and ask Billy Dixon.

True and False.

Rifle bullets are capable of traveling several miles, depending on the cartridge. Even the .22 LR cartridge can send a bullet over 1.5 miles (2640 yards). Accuracy is another matter.

To maintain accuracy, a bullet must remain stable in flight. Immediately after a bullet is fired it undergoes a steady deceleration. As the bullet slows, it eventually reaches a velocity slower than the speed of sound. Bullets fired at supersonic velocities become unstable as they approach and pass through that sound barrier. A bullet undergoing the transition from supersonic to subsonic is said to be transonic. High speed photos clearly show the changes in compression waves and turbulence as a bullet undergoes this change in velocity.


"These four photos show the substantial changes in the shock wave and turbulence patterns for the same 7.5mm bullet at different velocities. The “M” stands for Mach and the numerical value represents the velocity of the bullet relative to the speed of sound at the time of the shot."

A transonic bullet becomes unstable and will wobble, roll, and often tumble. The bullet will veer from its original path and accuracy is lost. The distance at which that happens depends upon the initial velocity and ballistic characteristics of the bullet, as well as the characteristics of the air through which it moves, i.e. temperature and density.

It is practicable to say, therefore, that "cartridge range is limited" by the range at which the bullets become transonic. It should be remembered that it will vary within a certain cartridge as well depending on the bullets used. A 200gr round nose .30-06 bullet at 2400 fps Vo may become transonic at 450 yards while a 165gr spitzer fired at 2800 fps Vo may not become transonic for 1200 yards, for example.

The .50-90 bullet fired by Billy Dixon was most probably a 700 grain bullet with a muzzle velocity of about 1100 fps. That would mean the bullet was never supersonic and, therefore, was not subjected to the instability of a transonic flight.

I understand the recoil portion of the discussion.

That said, increased MV, by using the same high(er) BC bullets, in a larger capacity case has to be an advantage at extended ranges.

Velocity loss should be more or less a constant as range increases, regardless of the cartridge if the same bullet is used.

IE; if I start a bullet 500fps faster, it does not seem logical that it will lose velocity faster, as a percentage of loss over the flight than one 500fps slower.

The Billy Dixon shot was replicated, basically, by Mike Venturino at Yuma many years ago. Forensic Scientists at Yuma had postulated, in a paper read at their association annual meeting that it was impossible. Mike had a great time, shooting one of his Shiloh rifles, in 50-90, with Black Powder and hitting a target with roughly the frontal area three consecutive shots at just over the 1570 +/- yard distance.

I missed that one, but did attend the one four years later where a team proved that the Kennedy shot was indeed possible. They studied Oswald's service records and discovered he qualified shooting his service rifle (M-1) from his left shoulder. He had also been observed at a local shooting range shooting his alleged assassination weapon, a bolt action rifle from his left shoulder and rolling the rifle over to his left to manipulate the bolt. They were able to replicate the shots fired, and the time. They built a Lincoln replica, had it towed with a strap by a member with (iirc) a pickup.

Cartridge is part of the problem, so is twist rate. Given a bullet of proper BC, at a enough velocity, and a barrel with the right twist rate a bullet can be accurate at 1K or further. Take a 77 grain Sierra Match King as our bullet, in a 20" Service Rifle(AR 15 .223/5.56) the max range is before dropping subsonic is about 800 yards. Same bullet, same cartridge, same load in a 28" barrel bolt action makes 1K. A .30 cal 175 grain SMK in a .308/7.62 will do 1K, a .30-06 will do better, a .300 Win Mag will do it and can do it with heavier bullets also.

Without looking up bullets and twist rates my guess would be that for the RUM or STWs that there hasn't been much long range match with them or the standard factory hunting barrels aren't the right twist for high BC bullets.

PS: in a .223/5.56, a 80 to 90 grain bullet will go 1K out of a 20" barrel but it is at the extreme for pressure. A while back when I wondered about .22-06 idea in a fast twist for 90 grain bullets someone brought up the the idea of the rear surface area of the bullet and pressure in the chamber as parts of max velocity. The thought was eventually you hit a point where no matter how much chamber pressure and gas you generate that the bullet only gets so much out of it and the rest is just exerted on the bolt and chamber. Looking at a 6.5 in a .223 parent case this makes some sense.

Shot for some years a Rem.700 w/Douglas barrel in 22-250, 8 twist, 80gr.SMK's prone NRA Long Range matches and at the 600yd. matches would routinely shoot in the high 590's. Never able to "clean" the match, but X's about half the time. Highest score for the 1000yds. was 193 w/ few X's. Dropped points, X's, were not due to the caliber/rifle, but the ability of the shooter, me. Currently have Ruger No. 1 in 22-250, 7 twist and both 80SMK's and the 90's do just fine. Rifle has Unertl 16x on it and later in Feb. going to introduce some coyotes to the rifle. Rifle is a pleasure to shoot for very little felt recoil and accurate if I keep the velocity at some 3100fps. You can get more, but accuracy degrades or at least for me it does.

quote:

Originally posted by Idaho Sharpshooter:

Velocity loss should be more or less a constant as range increases, regardless of the cartridge if the same bullet is used.

IE; if I start a bullet 500fps faster, it does not seem logical that it will lose velocity faster, as a percentage of loss over the flight than one 500fps slower.

Fluid Dynamics 101: the resistance of a moving object through air is a function of the square of its velocity. Stick your hand out of window in a car going 25 mph, then speed up to 50 mph - the resistance is not double.

It might be hard to believe ISS, but it is true.

thanks all.

It would seem to indicate (strongly) that recoil is the limiting factor unless weight of the firearm is not a consideration.

Also.. spindrift and corealis effect both pulls the bullets to the right.

You should try to order a LH twisted barrel as it will cancel out some of the corealis effect!



And, add to that if you are shooting east or west, bullets will impact higher or lower at longer ranges.

Purely consumer perception.

Send the same bullet faster, it'll go further for the same drop and drift. A nice brake goes a real long ways, and makes my 338 Lapua Improved easy to shoot, lightweight GF was hitting a target almost 1000 yards away every single time, with a breeze. A 6.5 Creed isn't going to get it done the same with a novice shooter.

Bullet selection plays a large part too. Put a 208 Amax in a 308 and you can shoot it accurately to a mile, even though it's WAY subsonic at that distance. Put a 168 SMK in a 308 and you can't even hit at 1000 repeatedly. Some bullets respond poorly to the transonic barrier, and some don't even seem to be impacted.

Billy Dixon was shooting a 50-90 Sharps he had borrowed from Shepherd, the bartender. He was using Sharps factory ammunition. Dixon stated in his autobiography that he had run low on ammunition and had replinished his ammo supply by making a dash from Hanrahan's saloon to Rath's store where there were thousands of rounds of ammunition. This was factory ammo, not reloads. The standard loads were a 425 grain bullet over 100 grains of powder, and a 473 grain paper patched bullet over 100 grains of powder. These gave a velocity of something on the order of 1325 fps. The original Sharps had a barrel twist of 1-36, hence the shorter, lighter bullet.

One more bite of the apple, if you would allow me...?

I am going to barrel one of my rifles in a good 8.5" twist 6.5mm caliber.

A lot of good accuracy work is being done with the Berger 140gr Hybrid bullet, and I have a generous supply.

The 6.5-284 is capable of well under moa accuracy with the velocity right at 2950fps.

The 6.5 RUM has me thinking, it will run that same bullet at 3400fps, supposedly with similar accuracy.

I ran Berger's Ballistic Calculator at both velocities, and the RUM drops -15.24moa versus -22.29moa for the smaller case. Over six feet at a thousand yards.

Do you think that decreased drop, across the board, is worth a couple hundred extra dollars for a two reamer set with gauges, and higher priced brass is a worthwhile trade off?

thanks,

Rich