Hello all,
After being very successful with my 90 grain, .224 caliber, lead core bullet, which stabilize at about 3818.18
RPS and a rotational velocity, on the skin of the bullet, of 2686.918517 inches per second. Which relates to a muzzle velocity of 2450 FPS from a 7.7-inch twist. I started for the first time to see what I could do with a powder tungsten core bullet.
The first thing I noticed, to my surprise, was that while a lead core stretched the jacket cup, the powder tungsten contracted or shortened the jacket cup. The more compression I got from the powder the shorter the jacket cup became. While the lead core bullet of 90 grains is 1.087 ± 0.0005, a growth of a several hundredths of an inch, the tungsten powder core bullet of 97 grains is 0.965 ± 0.0005, a contraction of well over a tenth of an inch. The stretching of the cup with lead is due to the cups walls getting thinner during the core seating operation while the reverse for tungsten is due to the powder granules dig into the cups walls taking the copper with the powder thickening up the cups walls.
This is very significant for ballistics. By switching to a denser core will allow for a slower twist rate or for less of a muzzle velocity to stabilize the bullet. On top of the denser core, I was able to get a heavier bullet in a significantly shorter bullet length that allows for a further reduction in the twist rate of a firearm. This can mean for the competition shooter, that he/she can use an unusually slow twist rate then normal that will allow for a faster muzzle velocity then would normally be possible for that same weight bullet in a lead core configuration. And as we all now a higher cross sectional density relates to a higher Ballistic Coefficient.
A regular copper jacketed lead bullet has a Specific Gravity (SG) of 10.9 whereas my copper jacketed powder tungsten, with my specific compression, has a SG of 13.1 (more precisely it is 13.05483768). This relates to a normal twist rate of about 1: 6.9 at 2250 fps and about 1: 8.3 and slower at velocities above 3000 fps compared to a powder tungsten bullet of the same length with a SG of 13.1 of about 1: 7.5 at 2250 fps and about 1: 9.1 and slower at velocities above 3000 fps. Now lets correct this for the length difference. The 1: 7.5 at 2250 fps becomes 1: 8.5 and the 1: 9.1 and slower at velocities above 3000 fps becomes 1: 10.2 and slower. This means that the bullet even though it weighs more can be pushed out the muzzle at a faster velocity.
In summery, the competition shooter will benefit from a much greater BC, higher velocities, and less Lag Time for flatter shooting and less Wind Deflection.
Also on the bullets that get messed up, the recovery of the powder is easy, just use a clean container and squeeze the bullet with a pair of pliers so the powder of course pours into the container.
Why? You might ask. And is it worth it?
Well, I had fun, fun, and more fun. I dont know if it is worth it, thats up to the shooter using the bullets. Is it beneficial in all shooting conditions? NO. The type of bullet used should always reflect the type of shooting being done. The bullet type should always follow purpose, purpose, and purpose.
Donna :wink:
