400 FPS under manual?

J

Jevyod

New member
I loaded up some 55 grain nosler varmint bullets for a 243. According to nosler, I should have been getting 3950 with the load I was using. I got 3485. That got me wondering as to why the big discrepancy?
Load info...Once fired Rem brass, CCI#200 primer, powder was 50 grains of H4350. Projectile was Nosler 55 grain Varmageddon. Average velocity was 3485 with an ES of 32. OAL was 2.710 (.015 OFF LANDS)
Rifle is a Ruger M77 MKII with a 22 inch barrel. I did notice in the manual that they have an OAL listed at 2.590. Would that alone make that difference? Or is something else happening here? Am scratching my head on this one...
 
Relax. A lot of variables there. Each of the components going into your loads are from a different batch than what the Nosler gang found in their testing. All they can do is tell you what it did for them. Now you tell us what it did for you. Thanks for the report.
 
Nosler tests their ammo using a 24 inch Lilja barrel and Nosler cases with a volume of 53.0 grains of water and a Remington 9 1/2 primer. This could account for some of the difference. I have seen velocity both increase and decrease with the round count on the barrel, speeding up for the first couple of hundred then decreasing a couple of hundred when the barrel gets into the mid 1K range.

H4350 is pretty stable temperature wise with a .35 fps/f burn rate but temps could be a minor factor

Then there are chrono accuracy factors. How much faith do you have in the chrony? Can you zero at 100 and then dial in at 500 + and be within a half MOA or better on elevation?

Using my balistic calculator using the hollow point Varmageddon you are stable out to about 500 yards and with the tipped you could stretch it out to 700 or so and still be stable

If it is accurate at the distance you plan on shooting then I would not sweat the numbers too much.
 
That's a big swing. The 2" barrel difference, nor the primer selection would cause such a variance. My first reaction would be to verify the Chronograph was set up properly [mine had the ability to change the distance of the screens. Generally, if things are off, I've placed them too far apart or close]. If the chrony is OK, I'd pull a bullet and reconfirm the weight of the charge. I checked the Hodgdon website, but they're not showing H4350 as a powder selected for the 55gr. It doesn't pop up until you get to the heavier bullets.
 
Using a 24 inch Lilja barrel with a 1 in 10 rifling twist. Book velocities are averages, but only matter if your rifle is exactly the same and so are the climatic conditions.
Your Ruger uses a 1 in 9 twist and is 2" shorter. That will change your velocity results. Wouldn't worry about it if the load is accurate though.
You work up to the 50 grain max load or just pick it?
Kind of odd the Hodgdon didn't test H4350 with 55 grain bullets. They didn't test IMR4350 with 55 grain bullet either though.
 
I had a similar issue when I was working up loads with Superformance powder. I was under velocity by almost 200fps. My seating depth was based on a miscalculation I had made on my lands distance. I thought I was just off the lands with a COL of 3.375 when I was in fact jamming. I had high pressure signs and stopped. Later I seated the bullets deeper to a COL of 3.320" which was actually .010" off the lands. It put me right on with Hodgdon's data.

Speaking of Hodgdon. Their latest data does not list H4350 for that bullet. What Hodgdon does list never comes close to 3950 FPS which is really fast! The powder charge that you are using is also a compressed charge. Case volume could come into play there too.

One more thing. you might go back and double check your COL a while after you load. Sometimes compressed loads will push the bullet back out.
 
One reason I see is the use of such a "slow" powder with a very light for caliber bullet in a "short" (vs 24-26" anyway) barrel. Three strikes right there.
 
From my experience i've found the Nosler manual optimistic to word it nicely.

Pure fantasy to word it not so nicely.

Still don't know why in the world i bought their latest manual...
 
I was also wondering about the powder being on the slow side. I will try a powder with a faster burn rate something in the IMR 3031 range.
 
Jevyod wrote:
That got me wondering as to why the big discrepancy?
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Well, you used different components and shot them in a different rifle. You should expect different results.

I did notice in the manual that they have an OAL listed at 2.590. Would that alone make that difference?
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"that alone" was probably not enough to explain the entire difference, but it would certainly be a factor in it. When you seat a bullet deeper or shallower than what is in the published load data, you can dramatically change the power's burn characteristics. Most people are familiar with the fact that in its commentary on the 9mm Luger, many editions of the Speer Manual (page 385 in the 11th edition) the authors noted that bullets seated 0.030 inches deeper than they were supposed to be essentially doubled the chamber pressure.

With that in mind, could a difference of 0.120 inches make a big difference in the results you got? It's certainly within the realm of possibility.

If you want the results the publisher got in the book, then duplicate what the publisher did in the book. Don't change it to suit your own preferences and expect to get the same result.
 
My 243 likes 4064 and RL 17. I also agree that real world results at the range are usually different than the manufacturers lab. For the record, I've always seated bullets to the listed OAL without issue. When you get to 30fps or less ES, you've got an accurate load.
 
"Am scratching my head on this one..."

I have to ask: Why do you reload? For me at the beginning it was to save a few bucks on the ammo I was shooting. Later as I got into it, it became interesting to work up a load for the rifle in use and get those loads to repeat. IOW hit the same spot each shot. I have never used a chrono. I don't really care how fast they are going, what I do care about is hitting the target!
 
IOW hit the same spot each shot. I have never used a chrono. I don't really care how fast they are going, what I do care about is hitting the target!
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Like you I rarely bothered with a chrono during load development. It was used mainly just to get a velocity on the load I settled on for ballistics calculations. I have just recently discovered the wonderful world of velocity flat spots. Once you grasp that theory it starts to make sense why a chrono can be useful for initial development.

Now I don't sweat the flyers or wind when developing a load . If I find a good node 3 or 4 tenths wide I don't have to be so picky on whether the powder measured is 41.1, 41.2, or 41.3 grains. If I load for 41.2 and the load is really 41.1 or 41.3 grains due to scale error it will give me the same velocity within a few FPS. That way I can be pretty much assured that the bullets will hit in the same spot if I am using good technique and the wind does not send me off to la la land

Do a internet search for velocity flat spots, the theory has been around for a while now but I just learned of it myself

edit - you can accomplish the same thing and find those wide nodes without a chrono by using Dan Newberrys' OCW method

here is a link where Newberry himself chimes in down in the comments section.

http://www.65guys.com/load-development-part-1-of-2/

The theory goes back to at least 2013 when Erik Cortina posted about it

http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/
 
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QL tells that that with...
- That bullet
- That barrel length
- That Powder
- That weight
- That OAL...

I should looking at 3,700fps/63ksi/95% burn.

If I'm off by 50fps w/ QL, I'm not surprised.
100fps... then I'm mildly surprised.
....but more that 200 ?

I'd go back and double check things.


.
 
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[QUOTEMy 243 likes 4064 and RL 17. I also agree that real world results at the range are usually different than the manufacturers lab.][/QUOTE]

I don't load for the cartridge but thought 4064 burn rate is where I thought would be the next try for the light bullets . IMR 3031 seems like a really fast powder for the cartridge .
 
There are a lot of factors that can account for slower speeds. All have already been mentioned. But all of those factors combined shouldn't account for over 100-150 fps difference.

Just guessing, but I'd check to be sure that both the scales and chronograph are accurate.
 
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