Cup and Core bullet velocities.

Started by JamesNotBond, May 28, 2024, 07:45 PM

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JamesNotBond

Hi, what would the optimum launch velocities be for normal hunting, up to about 250 m, realistically 100 - 180 m actually.
I have heard a lot about bullets breaking up and failure at high velocities, I will be shooting .308 Win bullets.

Tripodmvr

The other post at present about the 303 makes me think back about my hunts with that starter rifle of mine. 180gr bullet at 2450fps and it brought home the bacon. Use a 200 meter zero and 13 inches low at 300m. No clicking of scope, but holding high on the longer shots. Even used it for springbuck hunts. Good killing power with that "low" velocity.

Treeman

I would hazard 2200 fps abouts impact velocity is as low as I would think expandable bullet velocity for hunting not varminting bullets. I would think above 2700 -2800 fps impact velocity is where meat damage occurs and core separation is likely.
 My .270 launch's at 3000 fps and 200 m kudu usually produce a core separated cup if any part of bullet is found.

The 7mm 08 154 gr is launched at 2650 fps and recovered cup and core have always been good mushroom examples. The 303 174 gr at 2550 fps has never allowed for a bullet recovery.
I am who I am - I am not who you want me to be.
Therefore I am me.

Ds J

I shoot 180gr Sierra Pro-Hunters at 2440fps in my 308. Scope setting is dead centre at 50m (2334fps), 2cm high at 100m (2231fps), dead centre at 150m (2131fps), 5cm low at 200m (2033fps) and 7cm low at 250m (1985fps).

I once shot a kudu cow at 320m and the bullet still went through. It was a lower chest shot. On closer shots, I have found the bullet beneath the skin of the opposite shoulder. These bullets were well mushroomed, and had roughly 60% of their original mass.

In my 222, I shoot 50gr Hornady Varmint SP @ 3200 fps. They are mostly used for head and neck shots,  and I have never recovered anything.

Treeman

Interesting question this, one I may have posted, asked before, what is the best combo of velocity in regard to bullet working and trajectory being good enough.
DsJ has a load much like the one I load in .308 and the trajectory is absolutely fine if you know what it is, it has dropped Buffalo and Waterbuck, but it's a bonded bullet I use.

180 gr bullet at 2500 fps does not please me, but it works, every time, I am still a bit stuck at the 2600 fps + for me to smile. I know its mental block thing, but under 2600 fps and I am not comfortable - no matter how many times I have proved myself wrong - 2600- 2640, anything, as long as its 2600 fps + and I am happy.
 :o 
I am who I am - I am not who you want me to be.
Therefore I am me.

Ds J

How much of your discomfort is due to the "bad" trajectory of the slower bullet?

The 270 with a 130gr bullet has a much easier trajectory than a 308 with a 180gr bullet.

Tripodmvr

Here are two trajectory tables to compare.

JamesNotBond

Quote from: Tripodmvr on May 30, 2024, 10:18 AMHere are two trajectory tables to compare.
******************
Thank you, would likely have been my next question  :D

Tripodmvr

What put me on the reloading path and moving to mono bullets was the following experiences. Many moons ago I started hunting with my 303 and PMP 174SP ammunition. After using it for a few years the meat damage was becoming a concern to me. The last straw was when I shot a warthog at about 50 metres distance. The shot anchored it, but the hog was still very much alive and needed a head shot to kill it. The bullet had broken the shoulder and cup and core had separated. The cup was in the shoulder and the lump of lead had diverted and was in the brisket meat. No particles had entered the chest cavity. This was at the published speed of about 2450fps.

Treeman

And here I am, moving back to cup and core for everything other than specific applications where the extra penetration may be needed.
 I am also moving away from speed + some more.
I am who I am - I am not who you want me to be.
Therefore I am me.

Ds J

Quote from: Tripodmvr on May 31, 2024, 08:32 AMWhat put me on the reloading path and moving to mono bullets was the following experiences. Many moons ago I started hunting with my 303 and PMP 174SP ammunition. After using it for a few years the meat damage was becoming a concern to me. The last straw was when I shot a warthog at about 50 metres distance. The shot anchored it, but the hog was still very much alive and needed a head shot to kill it. The bullet had broken the shoulder and cup and core had separated. The cup was in the shoulder and the lump of lead had diverted and was in the brisket meat. No particles had entered the chest cavity. This was at the published speed of about 2450fps.

Poor performance of bought ammunition moved my father to reloading too, and that was 40 years ago.

He took a shot at a kudu at 180 or 250 meters, the bullet hit the ground at 80 meters.

I tried monos, but moved back to C&C. I would like to try copper mono's again, but still have enough C&C's for quite some time.

Broken up bullets have not given me much headache. Bullets hitting bone cause much damage to meat, irrespective of speed. Faster bullets are said to make more slimey/gooey wounds, but I am not so sure of that.

janfred

Quote from: Tripodmvr on May 30, 2024, 10:18 AMHere are two trajectory tables to compare.
Now show a comparison between a 150gr at the usual speed and a 180gr at the usual speed.

Tripodmvr

150 vs 180 in 308. Calculated to safe pressures and on a node. Used hunting bullets in both instances.

Newton

Quote from: Tripodmvr on Jun 01, 2024, 10:28 AM150 vs 180 in 308. Calculated to safe pressures and on a node. Used hunting bullets in both instances.
Velocity falls off very quickly and drop increases quickly past 300m
Try now with some high BC very aerodynamic VLD style [ hunting ] bullets

Treeman

I often hear the guys spouting, "ja! see, its only a inch more and less. Do they even know what they saying?  If your shot at 250 m is 2 inch's off shooting field positions, that extra inch up or down may work in your favour.
Huh ? - well your under pressure guestimate distance was of by 2 inch's low and you shooting 2 inch's high because of distance, you may just hit fine and well. Same error at opposing side of scale, and you out by 2 inch + the 2 inch extra drop and its a wounding shot. Two inch's drop or high + user error can add up to a big fkup.
Now you shooting a flat cartridge and you aim spot on and its half inch high + or minus you 2 inch bad shooting, you have two more inch's off "OFF the mark" before you miss the lungs over under.
We not going to talk headshots, because  being out of range by 70 m would mean head instead of brain.
I believe that shooting after 200 m with a rifle that has 6 - 7 inch up down total variation from zero becomes complicated and opens doors to much "if only!"
Heavy for caliber application needs to stay inside the 200 m shooting zone if you not a avid tracker and do not mind the occasional loss of an animal.
 
I am who I am - I am not who you want me to be.
Therefore I am me.