Precision 6.5 CM - What would you change about my process?

[45-90]

Wow, that Hornady 108 gr "match ammo" is quite horrible for velocity consistency.
Feb 6, 2126 on the digital readout over 100 yrs into the future....you'd think they'd have improved on their ammo 100 yrs into the future.

 

[Barelstroker]

Approximately speaking, if the distribution is fairly normal and the SD=6 from a good sample, and you kept shooting, you would come close to an ES of roughly 36.

ETA: the basic principal of the ES of a "normal distribution" is that the two "tails" of the distribution span roughly six sigma, so 6x6=36

I've resisted commenting on many other threads where the infamous "velocity SD" is invoked in it's raw & ignorantly bromidic form as a means of measurement in & of itself.
In reality, SD is little more than a statistical, mathematical concept specifically utilized to obtain relevant data.

 

[RegionRat]

You can't let it get under your skin. Help out when you can or the next generations are doomed.

 

[GBMaryland]

Wow, that Hornady 108 gr "match ammo" is quite horrible for velocity consistency.
Feb 6, 2126 on the digital readout over 100 yrs into the future....you'd think they'd have improved on their ammo 100 yrs into the future.

To be fair, different lots of ammunition we will have different properties.

And that is a very small sample of 20 rounds… I would expect to get better with a larger sample.

Hornady certainly had some horrible manufacturing during the COVID timeframe, and I suspect this lot came from then.

The Berger did better, as has the Norma.

Certainly not my best day shooting, but here is a test target at 100 yards for the 109 grain Berger:

The central group is about half an inch and about 13 shots.

Really need to take my time and shoot at 300….

 

[straightshooter1]

I thought as much.
So, with a well established SD of 6, what should we anticipate as a realistic ES over the long term?

I think you can count on that number RegionRat stated. However, my data shows I get about 5x, often around 4X the SD for an ES. Keep in mind when talking about ES's, we're only talking about the measurement between just two data data points in a set.

Here's an example from my data: for a 50 shot set I got and SD of 5.4 and and ES of 23; another 80 shots with a an SD of 6.2 has an ES of 29. Then there one like this: 45 shots for an SD of 20.4 with an ES of 87. This latter one was telling me there was something very wrong with my load and the only thing that was different from other loads was the primer; so that SD gave me a good idea what to look at.

 

[kthomas]

My thoughts:

- I'm not sure what powder you are using, but use one that is known to have great success for 6.5 CM. H4350 is the go-to here, but there are other options too
- I've always found Hornady brass to be somewhat limiting when it comes to achieving the best SD/ES. I have better results with Lapua SRP brass
- Seat your primers as deep as possible
- Use 2 to 3 thou neck tension
- Reloading is all about consistency. Consistent powder charge, consistent shoulder bump, consistent seating depth, consistent primer seating depth, consistent neck tension, etc.
- FL dies are fine. I use FL dies and get 6-7 SD with 6.5 Creedmoor
- IMO, annealing and trimming aren't going to be big needle movers for what you are trying to accomplish. These are items you can pick up later on down the road

 

[GBMaryland]

I primarily use annealing to prevent from over working my brass, in general. Otherwise, not a really big deal depending on the brand of brass.

I've gotten as low as a 4SD on new Prime (Norma) brass in 65CM / 147ELDM

 

[_Thor_]

My thoughts:

- I'm not sure what powder you are using, but use one that is known to have great success for 6.5 CM. H4350 is the go-to here, but there are other options too
- I've always found Hornady brass to be somewhat limiting when it comes to achieving the best SD/ES. I have better results with Lapua SRP brass
- Seat your primers as deep as possible
- Use 2 to 3 thou neck tension
- Reloading is all about consistency. Consistent powder charge, consistent shoulder bump, consistent seating depth, consistent primer seating depth, consistent neck tension, etc.
- FL dies are fine. I use FL dies and get 6-7 SD with 6.5 Creedmoor
- IMO, annealing and trimming aren't going to be big needle movers for what you are trying to accomplish. These are items you can pick up later on down the road

I'm reading elsewhere that 1.920" is the max allowable length for 6.5 CM brass. So basically as long as I'm under that, I don't need to worry about trimming, right? Would consistency be affected much if mixing brass of different lengths?

 

[kthomas]

I'm reading elsewhere that 1.920" is the max allowable length for 6.5 CM brass. So basically as long as I'm under that, I don't need to worry about trimming, right? Would consistency be affected much if mixing brass of different lengths?

If you are not going beyond max length, it shouldn't present an issue. You should be able to at least get a few firings before you reach that point, but keep an eye on it.

And to your last question, I actually don't know. I'm not sure how much brass OAL variances would or wouldn't affect performance.

 

[Barelstroker]

I'm reading elsewhere that 1.920" is the max allowable length for 6.5 CM brass. So basically as long as I'm under that, I don't need to worry about trimming, right? Would consistency be affected much if mixing brass of different lengths?

As long as you're checking every case for length & not taking sample measurements as 6-5 Creed has only about .005" between chamber & case dimension &, cases can & do grow at different rates.