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Hornady Podcast Reloading

The way I would apply this to let's say my new 300 prc I am going to start loading for which I have never shot.

Take my bullets (205 Bergers)

Take my powders I want to test

H1000
Retumbo
N570
RL26

Load 1 bullet in .5 increments over the powder ranges for total of 10-15 bullets

Shoot those 10-15 at the same target. Find 5-9 bullets with similar POI within the "dispersion/spread" i want. 3/4" Hunting.

Then take the middle of that grain drop spread, load 20-30 of those. Shoot them all. That will give me my true spread.

If I don't like it, switch powder, then switch bullets.

Anyone see anything wrong or suggest different. The part that was interesting was their techinician saying that from your Min. to Max. powder range, you most likely will not see a huge variance and to just pick a single grain drop and shoot all those 30 at that range and it will tell you what that powder and bullet combo will do.
 
The part that was interesting was their techinician saying that from your Min. to Max. powder range, you most likely will not see a huge variance and to just pick a single grain drop and shoot all those 30 at that range and it will tell you what that powder and bullet combo will do.
Yup.

Just last week I shot a 0.75" group at 100 yards - it was 11 shots, charge weights laddered up by 10 grains, and the ES was 262 FPS. The first 9 shots were under half an inch, I really blew up the group on the last two shots 🤣 I shot another powder that was about 1", and a second that was awful, almost 2". Guess which one I'm working with?

Yes, massively different charge loads will shoot together at 100 yards. Short range benchrest shooters are able to load with a volumetric charge drop at the bench instead of an uber-fancy lab balance weighing to the 0.01gn/ half a kernel of powder because velocity just pretty much doesn't matter for precision close in - the inherent precision of the system matters a whole lot more.
 
Yup.

Just last week I shot a 0.75" group at 100 yards - it was 11 shots, charge weights laddered up by 10 grains, and the ES was 262 FPS. The first 9 shots were under half an inch, I really blew up the group on the last two shots 🤣 I shot another powder that was about 1", and a second that was awful, almost 2". Guess which one I'm working with?

Yes, massively different charge loads will shoot together at 100 yards. Short range benchrest shooters are able to load with a volumetric charge drop at the bench instead of an uber-fancy lab balance weighing to the 0.01gn/ half a kernel of powder because velocity just pretty much doesn't matter for precision close in - the inherent precision of the system matters a whole lot more.
Wait, so you shot over a 10 grain change or you shot 10 grain jumps (110 grain change overall) haha. Making sure I read that rightl
 
I've listened to parts 1 & 2 and need to ask them a question because to me one thing wasn't clear: Does POI change for different charge weights?

I know they mentioned that all things being equal dispersion generally can increase with charge weight, but I don't remember if the directly covered if the zero changed as charge weight increased.
 
HA, ten 1gn increments. Pressure ladder with a new powder.
How did you choose you seat depth?

How did you choose your powder range?

And then after you shot you 10 shot group. How did you choose what to load further bullets in? Like how did yo narrow down form there?
 
Bullet choice was easy, I have about 3k Berger 153.5s so I used Berger 153.5s 🤣 These things are going to shoot in this rifle, the thing was set up from the reamer for them.

But for your 300 PRC pick something you can get 200-400 of a matched lot of right now, something from Berger or Hornady ELD or Nosler BT or AB.

How did you choose you seat depth?
0.020" off the lands. Gotta start somewhere, it's a place to start.

In your case book COL or mag length is just as good a place to start.

How did you choose your powder range?
Powders on my list were ones commonly used in 6.5-284 Norma, it's been a benchrest standard for half of forever so there is a ton of load data floating around for it. Loaded up to what QL spit out as the max and a grain past.

In your case match up with the book data for the bullet you pick. There's tons of Berger data all over the internet, and I suggested Hornady and Nosler because they each publish up-to-date loading data for the chambering. It might not be the coolest and sexiest thing to shoot Hornady bullets, the internet might even challenge your manhood about it, but there's solid data to work off of for your first time out with the chambering.

And then after you shot you 10 shot group. How did you choose what to load further bullets in? Like how did yo narrow down form there?
After I shot the pressure strings to make sure I didn't accidentally rearrange my facial parts with any of the loads, I decided to go with more of the same powder that shot the smallest group in the ladder, H4831. I was bummed that H1000 wasn't better, but RL26 was a real disappointment. It was the fastest but at more than double the group size it's not going to work in this barrel. Speed is nice but hits are better. If H4831 decides to suck then I'll revisit H1k, then after that I'd try something new. The magical pixie dust wasn't doing it for me in this gun.

I took the fastest three charge weights that didn't show pressure signs on the brass, loaded more of them. Sat them all long at 0.020" off, I can bump them back with an arbor press at the range if I need to change the seating depth.

Don't overthink it. It's a new rifle, it'll take some time to get it in the groove while you get you in the groove and get comfortable with what you're doing loading for it. Best bet is to load as many identical rounds early on as you can and get a real look at group size. Load as few as possible in 1gn increments from book minimum up to 1-3gn short of book max load for whatever powder/bullet combo you have, seat them to the book COL, and shoot all of them before you change anything. This will give you a basic idea of what the combo does. If it sucks completely so what, you get a firing on all the brass and some firings on the barrel and you get to shoot some. Second firing on the brass you can push up to the max, but if you start trying to max out pressure past book data then mark or trash any cases that click hard or don't eject easily. Use them for foulers but don't keep them in the rotation for load development work.

The worst thing you can do it get in a tail chase constantly changing up things too early. Cases like the 300 PRC are more forgiving that older designs, you have better case geometry to work with from the start so your shoulders stay set better and the cases don't grow nearly as fast as the old machine-gun shoulders like on the 30-06. So pick a combo, go with it, and if the rifle is worth a wooden nickel it'll shoot 5-10 shot strings under 1.25". If it does that then be happy with it and run a couple hundred through it, THEN come back as start changing things up. You might be amazed at the results you can get with book load data and factory rifle.

And don't worry about burning out the tube, you aren't anywhere in the neighborhood of doing that. Once you start cleaning the barrel with a steel brush on a cleaning rod chucked in a power drill you can start worrying about if the barrel is done. Rifles are for shooting, components are replaceable, shooting is a perishable skill set. There is no replacement for rounds sent downrange, that is the entire point of this loading exercise. Shoot more, even if it's not the perfect load.
 
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For me, it is real simple. I'm going to load ~ 10 shots to find bolt pressure. Then I'm going to back off about 2-5%. Their general opinion was lower pressure was usually more accurate fwiw.

Then load 20 at my std seating depth based on experience.

Then try to shoot 20 shots into 0.8 MOA. If on shot # 3, I'm at 1MOA, I'll pull those and try 1gr less. If still ng, I'll try another bullet. If still ng, I'll change something else. Maybe powder. They tried to suggest primers could make much improvement, but my own experience differs.

My goal is to get 20 shots under 0.8moa at 100 yds. Then I know I'm sitting on a solid moa rifle that will generally shoot way better 3 & 5 shot groups
 
Something that they didn't cover that much in the podcast itself, but was abundant in the comments, was that increased velocity increases dispersion. Physically this makes sense, since the faster a non perfect spinning object moves through a fluid, the more small imperfections cause changes and dispersion, which will lead to less accuracy. So the advice that miles was giving in he comments section, was that you should aim for a particular minimum acceptable velocity, and shoot a 20/30 round string or group. Validate that that group is within your acceptable size, and if it is you can push faster if you want to. In hornady's data, what they found is some powders and bullets don't increase in dispersion with regard to velocity enough to be statistically significant, and some do.

I'm a data scientist by profession, so the whole 3, 5, or even 10 shot group idea just seemed way to small from the get go. Usually I'm working with datasets that are minimum 500 data points. Statistically speaking, the minimum required number of datapoints in order to start to get some sort of picture of what the data looks like is around 30, which is why they recommend shooting 20 or 30 round groups. Technically 20 will not give you a good picture, but for our purposes you could probably be ok with a 20-25% variance from the true distribution of the data that a 30 point dataset would get you near. The way I do loading, is I will get a powder bullet combo, figure out what the expected velocity for the bullets would be using GRT, quickload, and book data (since velocity by and large is mostly linear you can plot and guess using book data....its technically not, but close enough for the range of velocities we're working with). I will then load 20-30 shots with that powder bullet combo that gets to the smallest expected velocity I want, then check the velocity and accuracy data based on those shots. I will also use CEP50 and CEP95 using some of my own scripts to determine how large of a circle (in moa) 50% of the shots are expected to fall into (with some degree of assumed error), and how much 95% of the shots will fall into. For the velocity I create a 95% confidence interval for the mean of the velocity and check what that falls into. If the velocity meets my minimum specifications, and the accuracy meets my desired accuracy (accounting for the error potentially increasing or decreasing this), then I keep that load, and most of the time I'll increase velocity to see if I can push things faster without having any significant changes in accuracy. If it doesn't meet what I like, I won't use that powder bullet combo for my "good loads", and will instead run crazy tests so I can glean some other info. (things like coal, crimp, temperature tests, etc). Better to get knowledge over something like that then to just throw away bullets.
 
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