To Greybeard and/or other longtime reloaders

[ZZTOP]

Hello all,
Just thought I would post these results from my range trip last summer.
The rifle is a Rem. 700 BDL syn. stainless in 30 06.
The load was from the Nosler 5th Edition.
150gr. Soft Points, 50 and 51gr IMR4895, CCI 200, new brass,
case length 2.484, over all length 3.20

The range conditions were 75 degres, hardly any wind, guns and ammo undernieth a canopy.
I managed to shoot the 51gr. load first and get the expected results.

Shoot 5 shots, let the barrel cool, shoot 5 more, record data.

Av=2965 fps
Es=7.99
Sd=5.65

After the barrel cooled the 50gr. load looked like this:

Av=3367 fps
Es=52.37
Sd=20.49

So how did I change this into an 06 Magnum?

Happy shooting
ZZTOP

[R.W.Dale]

How far away was the chronograph from the muzzle? Sounds to me like a chrony error.

[ZZTOP]

It was between ten and fifteen feet.
When I shot the .22 LR to test the Chrony I got the expected reading from that batch of ammo.
There were no outragouse reading in the second batch of 06's like you have with a Chrony error.

Happy shooting
ZZTOP

[RaySendero]

Wow! 150 bullet at 3,367 fps from an 06

Since last summer - Have you been able to repeat that velocity with the 50 grain load?

And what about the primers?  Did you notice how flat they were?

Cases?  Did you notice any splits in the neck?  Or any bolt sticking?

[R.W.Dale]

It was between ten and fifteen feet.
When I shot the .22 LR to test the Chrony I got the expected reading from that batch of ammo.
There were no outragouse reading in the second batch of 06's like you have with a Chrony error.

Happy shooting
ZZTOP

 I would reccomend setting the chrony at the very least 20 feet. I go 25 when doing rifle testing. You may have been chronographing some of the muzzle blast.

[Ramrod]

I wouldn't trust that chrony. I think you would notice exessive pressure signs (like having to hammer on the bolt to get it to open) if you get those velocities from a 150 grain bullet.

[Graybeard]

You got an erroneous reading on the chrono. If you had an Oehler 35P it would have notified you and discounted that erroneous reading.

[ZZTOP]

On the primers and the bolt lift, they looked and felt normal.
Both the 51gr. load and the 50gr load had identical conditions except the 50gr. load shot faster.

Like I said the Chrony was between 10 and 15 feet from the muzzle.
I get no erronious or wildly disperced reading on that session.

I took my buddy with me to help setup the equipment, but I was the only one shooting at that time.

The Chrony had a fresh battery that will last 40 hours continueous.
As you noticed the max load had low extreme spread, but the lower loads
Es. was not out of line either.

I loaded up another batch just like that one but have not shot it yet.
I was hoping an elder statesman here at Greybeards could explain the less-powder-more-speed thing to me.

Happy shooting
ZZTOP

[Patriot_1776]

Krochus wrote:

You may have been chronographing some of the muzzle blast.

That is most certainly what happened.  When you chrony rifle rounds, you definitely want it at least 20 ft. away.  Believe it or not, the powder granules can and do give false readings.  They can cause your chrony to give you a much higher reading than the bullet is really going.  I would suggest trying the loads again, and set the chrony back a few more feet.  

If you don't think that much powder comes out, try shooting a piece of cardboard (say an 18in. square or so) between 10 and 15 feet away like the chrony and you'll probably see some black specks on the paper (powder residue).

If it still reads over 3200FPS, then you got me. :|  


-Patriot

[Ramrod]

I was hoping an elder statesman here at Greybeards could explain the less-powder-more-speed thing to me.
Happy shooting
ZZTOP

I'm no statesman, but I will try very hard here to be a diplomat. :-)
You are not getting 3367 fps from 51gr IMR4895. :roll:

[jerkface11]

One other possibility. Do you have any of that ammo left? Pull a bullet and check weight of the powder charge. Maybe you bumped your scale when you were loading it and got a heavier charge.

[PA-Joe]

You gave us the fps but what did the two groups look like? That is more important than fps?

[Barstooler]

Chronographs don't measure "muzzel blast."  They essentially are photo sensitive and measure the speed of a "dark" bullet passing between the sensor and the "white" strips of plastic.   How dark a gaseous "muzzel blast" do you think it can measure?

[Graybeard]

You are very much mistaken. Chronos will definitely give false readings on powder gases and other distruptions if the screens are too close to the muzzle. As I said earlier you're NOT getting that velocity, it's a chrono error and as I said IF you used an Oehler 35P you'd know which shot was the error.

[Patriot_1776]

Barstooler wrote:

Chronographs don't measure "muzzel blast." They essentially are photo sensitive and measure the speed of a "dark" bullet passing between the sensor and the "white" strips of plastic. How dark a gaseous "muzzel blast" do you think it can measure?

No, they don't measure the muzzle "blast".  But the photo sensor is sensitive enough to "see" the dark shadow of a granule or granules of powder passing over.  The expanding gases travel much faster than the bullet, and can reach the sensor before the bullet can.  

How you may ask?

Easy, the shotgun effect is very likely.  When the bullet first exits, there is really no way for the powder to go straight out.  As the bullet gets farther away, the smaller powder granule might go under the bullet, and hence sail over the sensors before the bullet even arrives.  It is a common problem experienced when the chrony is too close to the muzzle of the firearm.  

Still puzzled?

Take a close look at my "Avatar" for a perfect example.  You can see powder particles ahead of the bullet even right after leaving the muzzle.

Also, as Graybeard said, the sensors may also be sensitive enough to notice and record "visual" disruptions.  Also caused by the blast being too close, those visual disruptions may trick the sensors into detecting it as the shadow of a passing projectile.    


-Patriot

[Barstooler]

By 15 feet the bullet is well in front of the shock cone.


A major Chrono producer lists this a problem:

1) Too Close to First Sensor - Both visible light and heat exits the muzzle of a rifle with the bullet. If the first chronograph sensor is flooded with a flash of light or heat "bloom" the velocity readings may be incorrect, produce an error or no reading at all. A minimum distance of 7 ft should be maintained between the muzzle of a large bore rifle and the first sensor. (10 ft. from the muzzle to center of the sensor bracket is industry standard.)

http://www.shootingsoftware.com/CEDMQA.htm

Note, that they say 10 feet is "industry standard."  And the thread originator said his was 10 to 15 feet.

But I'll defer to Greybeard.  Move the thing to a "measured" 15 feet and try again.

Barstooler

[ZZTOP]

I will load up another batch and try and head out to the range on saturday to see what I can come up with.

Ramrod Wrote"I'm no statesman, but I will try very hard here to be a diplomat.  
You are not getting 3367 fps from 51gr IMR4895. "

Ramrod you are right I wasn't getting 3367 from 51gr. IMR4895.
I was getting 2965 fps.

I was getting 3367 fps from 50gr. of IMR4895. :shock:
That's 1 grain less powder but 402 fps more speed.

Happy shooting
ZZTOP

[Ramrod]

Sorry I mixed up your two loads. But you are positively not getting 3367 fps with either one.