A Note for John Kepler - Slower Bullets Hit High

[Jim Tarleton]

John,

My response to your post recently might need revising.

I went out to my range this morning while waiting for my partner. We had to trim some horse hooves, including an unbroken stallion with a mare on location in heat. For those who have never tried this endeavor, it is akin to spitting in Dick Butkas' face.

I had two groups of 22 K-Hornet rounds to test. 1st group was a 40 gr V-Max in front of 12 grs IMR 4227 (fire forming load). The second group was the same 40 gr V-Max in front of 13.5 grs IMR 4227. Velocity of the first group averaged 2840 fps, the second group averaged 3140 fps.

I fired the first group first, totaling 13 shots, all right around the Bull. I then fired the second group, 5 shots, and much to my surprise, they grouped several inches below the slower velocity first group.

On this day, with my rifle, the slower bullet impacted higher on target than the faster bullet, all other variables equal.

I am just calling them as I see them, but I was wrong about this one, and I am man enough to admit it.

I tried to load a composite target showing the results, but the file was too large. I intend to repeat the test. I find it confusing to say the least.

The game is still afoot!

Jim

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[MEHavey]

But this slower/higher effect only occurs at close ranges, Jim. So your glass
is as half full as it is half empty.

:-)

[Jim Tarleton]

But this slower/higher effect only occurs at close ranges, Jim. So your glass
is as half full as it is half empty.

:-)

MEHarvey,

I must admit I don't quite understand the situation. The K-Hornet has so little recoil, it is difficult for me to believe that the added milliseconds in the barrel will raise POI that much; but right now, evidence (my own) indicates it does.

I am going to repeat the test this weekend. I have some 55 gr bullets that I might add to the pot. I want to understand the physics of the situation in my own mind.

It is interesting to say the least, but probably boring to most folks.

Is 100 yards considered close range for a K-Hornet?

Jim

[Jim Tarleton]

Sorry about misspelling your name. I know better.

Jim

[Hank Stone]

It's not boring to me I'm interested in your findings.

[Jim Tarleton]

Hang in there, Hank. There is more to come. I just ordered several hundred more bullets. The little K-Hornet is cheap to reload, comparatively.

Jim

[Bill H]

The lower impact of faster bullets is well known and can be shown in handguns, but I am surprised at it in such a low recoiling weapon as a hornet.

The cause may simply be different vibration pattern with different loads.

I have a mauser sporter still in 8mm which shows as much as a 24 inch change in elevation at 100 yds simply by changing bullet weight. I don't remember if fast is low or the reverse. I find this very odd, however. It cannot be simply the recoil factor.

[Jim Tarleton]

I have to agree with you. I may dampen the barrel to see if things change.

Jim

[Bruce McAskill]

Velocity and barrel harmonics go hand and hand here as well as the recoil.

[Jim Tarleton]

Velocity and barrel harmonics go hand and hand here as well as the recoil.

The barrel on my K-Hornet is a slim SS Hart barrel (all Hart barrels are SS). Due to its light weight and small crosssection, I expected heat to be a factor after a number of shots. It is not unusual for me to put 30-50 rounds through it in an afternoon. For that reason, I free-floated the barrel. I may put some upward pressure (5-8 lbs) on the barrel at the tip of the stock, but that is for a later day - maybe.

Jim