Ugly extreme spread........now what ?

5.56×250

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Finally bought a chrono to get serious about finding a 500yd deer load for my field rifle. THIS IS ON NEW BRASS . I found a load that shoots great at 100yds considering I'm just fire forming brass and making sure the barrel is broke in right. This string is shots 67 to 77 on a new barrel. Barrel has not copper fouled since round count 20.
Load is 41.8gns of RL16 behind a Berger 130 vld with cci br large rifle primers and Peterson LRP brass (new/unfired). Barrel was cleaned before this string was fired.

2805
2795
2787
2802
2798
2776
2827
2808
2814
2862

The barrel was getting pretty warm on the last 3 shots, but I didnt let any rounds cook in the chamber more than the time it took to chamber , square up in the graph window and squeeze the shot.
Am I looking for good ES too early in the process? Would you hunt for a better load, or relax and play with seating depths till I get the rest of this brass once fired, bumped, and weight sorted ? Oh, its s 6.5 creedmoor :D
 

shawnb

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I would shoot it at your intended range and see how it does. The first several shots look pretty ok. You dont intend on taking that many shots at an animal right, so take it to 500 and let 3 or 4 shots go. Let the barrel cool and fo it again.

Then come back and tell us how it did.
 

shawnb

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At 500yds and a spread of 100fps hi to low you looking at a spread of 3-4" roughly.

This is taken from our 6.5 creed with 143eld
 

5.56×250

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So, I'm hearing so far that the fact that its a new barrel and new ,unfired, brass that hasn't been sorted for weight or fire formed to my chamber isn't affecting the velocity spread?
Shawnb, I dont have a place to stretch it out in my present situation. I'm gonna have to rely on consistent known velocity and good ballistic data to dial in my DOPE . Hopefully I will find a place to shoot distance before the rifle season for deer comes around in October . Since my only hunting spots are wooded and unlikely to present a shot over 100yds right now, this build is more of a just in case rifle .
 

5.56×250

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You say the barrel was getting warm, did you fire these all back to back? That will increase the SD, and you can see that trend of increasing MV. I’d try all cold bore or three shot and see how it looks.
Yea, they were back to back, but not in a hurry. The barrel didn't have even a warm to the touch feel till about round 7. 9 and 10 were getting pretty warm.
I will load a few more and shoot them cool and see what shows. Thanks
 

5.56×250

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I would not worry about load development until after a 100 shots or so. Also, change powder to H4350. I think you will have much better luck.
I was thinking along those same lines on 100 shots. I have several groups of different seating depths loaded now to nail down what the rifle likes on that end. I think I will shoot those up before I check velocities again.
I guess it wont hurt anything to try and chrono those rounds too. I dont know if my chrono will read at my bench because of how shaded it is , but it wont cost anything to set it up and try.
Thanks for the input so far
 

86alaskan

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You'll find a certain amount of variation especially with virgin brass and a barrel that new. I'd load up some cheap practice rounds and not look for anything meaningful for another 100 or so rounds. My last 25-06 barrel got 150rds of break in and practice, then the next 50 were monitored for speed. at around 180 the speed steadily crept up until it leveled off around 195. it's been holding steady since then, another 300rds so far. Gotta let everything settle down before you get too worried.

I'll also second the wide spread doesn't do nearly as much as you think. Out to 600-800yds you can get away with an es over 20-30fps and not see too much on target. Smaller is better, but if your load holds up on target to your desired range, just spend more time practicing.
 

5.56×250

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I have a pound of h4350 , but I'd like to work the RL16 some more first. The RL16 is suppose to work good in areas where the temps get high like here in central Ga. It usually gives s little bit higher velocities too. I'm well below book max at 41.8 and looking at the velocities I'm getting, there is no problems with going up a little on charge weight. After I get all the new brass fired once, I'm gonna run some velocity ladders to see if there is a good node in there somewhere. Hoping it will be a little higher than where I am now.
 

sea2summit

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Yea, they were back to back, but not in a hurry. The barrel didn't have even a warm to the touch feel till about round 7. 9 and 10 were getting pretty warm.
I will load a few more and shoot them cool and see what shows. Thanks
Well I’m not a pro but excel tells me your SD for 10 shots is 22.6 and it looks like this. Average 2807.4
C87EA288-C550-4A75-87E8-7D0EB018FACC.png


Your first five rounds had an SD of only 6.2! Average 2797.4fps.
C4705280-5072-4D4B-BD32-35FBFAC9700E.png


Your last 5 have an SD of 27.8! Average 2817.4
5E3813FC-3E6D-49AB-B059-E4DD45443ACC.png


Maybe it didn’t “feel” warm but what’s going on inside the barrel may not have caught up, or your clean barrel may have needed to fill some gaps. I don’t really like SDs as a measure of accuracy I like proof at range and if I see an unacceptable vertical spread I’ll look closer at things like SD and extreme spread of MV.

Either way, I’d try for more consistency in the test before I started chasing the load around too much but I’m lazy:cool:
 

Tangent

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Jun 18, 2019
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Montana
10 data points is not enough to perform a detailed analysis. However, based on your numbers, the data is roughly described as follows:
ES = 86 fps
SD = [22.6, 23.78] range
Mean = 2,807.4 fps
Median = 2,803.5 fps
Confidence Level = 95%
Confidence Interval = +/-14.7 fps

In general, factory ammo out of my 6.5CM has a smaller SD than your data set. So in my opinion, if you're reloading you should expect better. As others mentioned, there may be other things going on in your test.

To put it in context though, if we are looking at a shot distance of 500 yards, we can roughly assume that ~90% of your shots will have a velocity between ~2769 fps - 2,846 fps. This roughly correlates to a differential in drops of ~3.1 inches/0.6 MOA/0.17 Mils. Depending on your skill level behind the rifle, this could be adequate.
 

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