Breaking the 4000fps barrier...

[Art Eatman]

The only things which increase muzzle velocity and therefore effective range in any particular cartridge are 1) longer barrel; 2) more pressure; and, 3) lighter bullet (maybe).

Barrel length is a function of the weapon's intended use, as well as the ballistics. More pressure than the SAAMI limit can be hazardous. A lighter bullet will slow down faster than a heavier bullet due to a lower ballistic coefficient, friction in air and less inertia--lotsa variables about when the heavier bullet begins to outperform the lighter bullet.

I'm not sure how much improvement there has been in rifle powders. I read through all the loading tables for data on the '06, for instance, and I see no reason to change from IMR 4064--and I've been using it for fifty years.

FWIW, Art

 

[Jamie Young]

Wow I didn't know 4064 has been around that long.

 

[Keith J]

Hyper-velocity?

5000 ft/sec and above are only possible in small arms by use of a tapered bore where the bullet is swaged to a smaller diameter in its passage through the bore. This was the case in the above referenced story of "normal Springfield pressures". The bullet started out as a .30 Caliber "coin" and was swaged down to a .22 projectile at the muzzle.

The 120 mm smoothbore on the US main battle tank shoots a saboted projectile at 5200 ft/second. The gun is smoothbored and the projectile is fin-stabilized for .5 MOA accuracy. It has a maximum range (NOT EFFECTIVE!) of 70 miles at 55 degrees of elevation.

As far as shaped charges, no way. You get a jet of plasma but its relatively short ranged. The thing that orks is a platter charge. I don't have the specifics but a lump of explosive is placed in intimate contact in the center of a round plate of ductile metal. The detonation wave is used to accelerate the remaining explosive and the plate with the plate asuming a conical form. Velocities in excess of 5000 ft/sec are possible with highly brisnant explosives. FYI, typical det velocity of cyclonite is 25,000 ft/second at dead pressed density.

As far as ever getting 4k out of an AR, forget it unless you want to shoot 35 gr bullets out of an A1 barrel. Why bother as the velocity will be below that of M193 even at 100 yards?

 

[12-34hom]

4000fps

I have a load using VARGET IN MY 6mm ack imp that chronographed at 4000fps. It shoots .4 moa with a 58 grain V - max bullet and is my current varmint load.

As far as barrel erosion goes, as long as you don't heat your barrel to extreme levels and you clean the barrel with proven methods, barrel erosion at 4000 fps is mininal. Some calibers lend thenselfs to barrel burn out because of the design of the parent cartridge. Overbore rounds like - 264 winchester mag, Weatherby, alot of necked down wildcats etc....


The 220 swift is labeled as a "barrel burner" and it just ain't so. I had a 243 with a barrel [factory] that went south after 1900 rounds. Sure, i ran some "hot" loads thru it but 80% were garden variety loads straight out od reloading manuals.

I have found that Herc powders, [reloader # 19 - 22 - 25 seem to burn "cooler" along with Varget also. I'm very careful not to heat up the barrel while shooting at the range or hunting.

I don't think a 223 lends itself to be loaded to this level, and proven loads that group well; are below the 4000 fps mark. The 223 is a great cartridge, but there will always be reloaders out there pushing the envelope trying to squeeze to most out of any cartridge, so be it!