55gr Hornady Z-Max .223 and Varget, results not linear?

inerlogic

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so.... after charting my data.....
i noticed a dip....

varget.jpg

arithmetic means:

grains FPS
22.8 2555
23.2 2806
23.7 2888
24.6 2785
25.0 2853
25.5 2917
26.0 2978

(26.4 listed as max by Hornady)
(should've thrown a 24.1 in there too.. hrrmm... maybe next weekend...)
 
actually... i did shoot on three different days, the first group, the next 3, then the final four, with was about the same all three days, hot and shitty.... and each time i shot 20-30 rounds of factory stuff to get some heat in the barrel before shooting the reloads....

didn't think it would make *that* much of a difference though....

i'll be doing some .308 loads in a few weeks.... i'll be sure to shoot them all the same day and see what happens...
 
10 rounds each, all once fired and full length sized, trimmed (1.750-ish") remington brass....
same weight projectiles for each set of 10 (for the most part)

powder and projectile weights to the accuracy of my scale, 1/10 grain
 
xtry51 said:
Which was the most accurate?

The one i didn't list up top by accident... 24.1 gr varget
MOA was something like 1.05 average to center was like... .313" or something.... All the numbers are on my computer..... I should post the data.....

25.5 and 26 were right there with 24.1 speed-wise.... But the spread was greater....

Rifle is a savage axis xp....
 
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Don't rely too much on consistent velocity. Often, the most accurate load does not have the most consistent velocity.

ETA: I've learned to not rely heavily on chrono data from different sessions. Try this next time you're at the range with your chrono: Measure a few rounds, then twist your chrono a few degrees so that the rounds pass over at a slight angle, and check a few more. You'll shit.
 
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ETA: I've learned to not rely heavily on chrono data from different sessions. Try this next time you're at the range with your chrono: Measure a few rounds, then twist your chrono a few degrees so that the rounds pass over at a slight angle, and check a few more. You'll shit.

I would think it is much more sensitive to the coplanarity of the beams. If the chrono wasn't unfolded exactly 180 degrees or the two sensors weren't parallel it would be a much bigger error than having a slight angle between the projectile crossing the beams. It's a cosine of a small angle effect so 5 degrees would only be a 0.4% error (cos 5) and 10 degrees would only be a 1.5% error (cos 10).
 
yeh, the speed thing was to see how i compared to what the red book says... and to make sure i'm not violating any physics laws and building a pipe bomb, for me the proof is in the paper :)

that being said, here's the paper:

22.8.jpg

23.2.jpg

23.7.jpg

24.1.jpg

24.6.jpg

24.6_2.jpg

25.0.jpg

25.5.jpg

26.0.jpg


Temp: hotter 'an 2 rats f****** in a wool sock
humidity: balls stuck to thigh
gravity: earth standard
 
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and just so the factory guys don't feel left out....

Hornady Factory Z-max 55gr:
(no cannelure on these oddly enough, though the bulk box of projectiles i bought are all WC)

hornady factory z-max.jpg

Winchester Ranger soft points 62gr

winchesterrngr62.jpg

PMC Bronze 55gr

pmc_bronze.jpg
 
I would think it is much more sensitive to the coplanarity of the beams. If the chrono wasn't unfolded exactly 180 degrees or the two sensors weren't parallel it would be a much bigger error than having a slight angle between the projectile crossing the beams. It's a cosine of a small angle effect so 5 degrees would only be a 0.4% error (cos 5) and 10 degrees would only be a 1.5% error (cos 10).

It ends up being worse than that because the beams are cones and not lines, and the sensors' ability to pick up an object is greater near the middle of the cone. If you send the bullet through the sensors on the outsides of the cones (as opposed to down the middle), or through the middle of one beam and near the outside of the other, not only are the beams farther apart, but the bullet has to travel farther into one of the sensing beams to be picked up by the sensor.

Remember, we're talking about the error when you set the chrono up for a new session and compare it to the readings from a previous setup. Distance to the chrono is on factor, the 'levelness' and alignment can also introduce error.
 
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It ends up being worse than that because the beams are cones and not lines, and the sensors' ability to pick up an object is greater near the middle of the cone. If you send the bullet through the sensors on the outsides of the cones (as opposed to down the middle), or through the middle of one beam and near the outside of the other, not only are the beams farther apart, but the bullet has to travel farther into one of the sensing beams to be picked up by the sensor.

Remember, we're talking about the error when you set the chrono up for a new session and compare it to the readings from a previous setup. Distance to the chrono is on factor, the 'levelness' and alignment can also introduce error.

Good tip. I haven't compared data across multiple sessions. So far I've done all my load comparisons in single sittings. I'm only looking for best groupings though, which for me so far haven't been at anywhere near max loads, so the chrono data is more just for my general knowledge. Also, as stated above, it adds confidence that I'm staying away from the pipe bomb zone [laugh]
 
I'm only looking for best groupings though, which for me so far haven't been at anywhere near max loads, so the chrono data is more just for my general knowledge. Also, as stated above, it adds confidence that I'm staying away from the pipe bomb zone [laugh]

I'm looking for small groups and different charge weights/velocities that group together (so that my good load is also 'forgiving'). Once I've found what I think is the optimum charge weight, I'll use the chrono to see how changing things like seating or sizing dies, seating depth, and other process parameters affect the ES and SD. The way I figure it, once I've found an accurate load, anything I can do to make the rounds more consistent will help.

I also use the chrono as a 'sanity check' to make sure the velocity is near where I expect it, and also to ensure that the velocity goes up when the charge weight goes up. If that doesn't happen, then you're in big trouble.

My experience is different than yours w/r/t loads near the maximum. I've found that with most common bullet weights, the optimum charge weight is within a few percent (below or above) the maximum. Think about it... the cartridge and the rifles that fire it were designed to take advantage of the full capabilities of the round. That usually means 'near the max'.
 
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Well I think it's an understatement to say you have WAY more experience than me. I don't have anywhere near enough diversity to claim whats working in the one gun (AR) I'm reloading for and the two powders I've created load data for are adequate to generalize broad based. I always heed your and other's advice wisely.

For my particular current load, I find best performance in the 2700-2750fps range for 62gr M855 with 25.0gr IMR4320, which is well below the max listed velocity of 2975fps, but close to the max listed load of 25.5gr. Maybe at 2750fps I'm in the near what you would consider max range because I'm close to the advertised max weight load (not velocity), but maybe I shouldn't be placing so much weight on the Chrono data? I've had others with experience check my fired brass with me for pressure signs and confirmed they all looked fine.

Feedback?
 
Feedback?
You're right in line with my experience. At 25.0 with a max of 25.5, you're at 98%. In my experience, the chrono data in the manuals is often optimistic.

Also, if you're getting your data off the Hodgdon website, keep in mind that their velocity was measured in a rifle with a 24" barrel. If you're shooting an M4 or even a 20" barrel, your velocity will be lower. You're pretty much 'near max'.

ETA: Their barrel also has a 1:12 twist. A slower twist rate will give a higher velocity and a lower pressure. If you're using a 1:7 barrel, I bet you're AT max if you could measure the pressure.

I bet if you took your loads and fired them in their rifle, you'd be much closer to the 'book' velocity.
 
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You're right in line with my experience. At 25.0 with a max of 25.5, you're at 98%. In my experience, the chrono data in the manuals is often optimistic.

Also, if you're getting your data off the Hodgdon website, keep in mind that their velocity was measured in a rifle with a 24" barrel. If you're shooting an M4 or even a 20" barrel, your velocity will be lower. You're pretty much 'near max'.

ETA: Their barrel also has a 1:12 twist. A slower twist rate will give a higher velocity and a lower pressure. If you're using a 1:7 barrel, I bet you're AT max if you could measure the pressure.

I bet if you took your loads and fired them in their rifle, you'd be much closer to the 'book' velocity.

You must spread some Reputation around before giving it to EddieCoyle again.
16" 1:7 twist. Thank you for the info [thumbsup]
 
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Some nice shooting there inerlogic!
I've used Varget in .223 with 55's, 69's and 75's. It's good stuff!

thanks! :)

oh 22" 1/9" BTW :)

just shooting straight on the bench, no rest or anything... i found the tightest groups were with the heavier winchester rangers... 50 and 55gr factory and surplus weren't as good....

but shooting from the rest... clearly the factory stuff is shite ;)
 
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