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

[Barrelnut]

Good stuff above about getting 100 rounds thru the barrel and getting brass fire formed.
IMO, after all of that, you should try to get the SD down to 10 FPS or below. 5~7 FPS is a noble goal.
Looking at your numbers, the last one is way out of the norm and is probably caused by "climate change", so I would throw it away for now. If you use the rest of the numbers you get: Average = 2801 and SD = 15. Not toooo bad , but really more like factory ammo.
I can usually get my rounds down to to the 5~7 range by using fire formed brass without too much weight variance, annealing it each firing, and using accurate and consistent powder charges. even consistent weight and bearing surface of the bullets can help.
Standard deviation is easy to calculate in a spreadsheet. there are also SD calculators online.
Below is a link to an online SD calculator AND an excellent article on SD and just what it means and how much it matters.
For the 6.5 CM, I use H4350 for accurate target stuff, but a lot of shooters use RL16 in the 6.5 and have excellent results with it. RL16 is close to H4350 in burn rate and is supposed to be temp insensitive as well.

Online calc:
https://www.calculator.net/standard-deviation-calculator.html
PRB Blog Article on SD:
https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/

 

[ppoole]

I agree shoot 3-5 let cool.

I focus on cold bore for hunting 1 round and let cool for 5-10 min for 3 rounds, and then fire 2 shots let cool 10-15 for 3 rounds so total of 9 shots.
1 cool
1 cool
1 cool
2 cool
2 cool
2 cool
Others do 3 sets of 3 round groups (all magnums however)

How did you find 41.8 of rl-16?

h4350 is one of if not the best powders out there hands down. In Georgia you will have high temps and low temps in winter, and with the temp stability it has you will have more confidence and confidence and mechanics is 90% of taking the shot.

 

[ppoole]

Barrel will get faster and fireformed brass will help with the numbers as well.

 

[Dean2]

ES and SD are primarily affected by neck tension, variation in case capacity, case fill, powder and on rare occasions primer, pretty much in that order of importance. Work on one variable at a time. Take your fire formed brass, uniform the flash holes, weight sort it and check the neck thickness, or get some Lapua brass to work with. If that doesn't cure the ES look for a powder that gives you as close to 100% case fill as possible and is the slowest powder that produces top velocities (in this case 4350 and the H version is an Extreme series powder and is at least as temp stable as RL16). If that doesn't get you the ES you want try CCI BR primers.

 

[5.56×250]

I agree shoot 3-5 let cool.

I focus on cold bore for hunting 1 round and let cool for 5-10 min for 3 rounds, and then fire 2 shots let cool 10-15 for 3 rounds so total of 9 shots.
1 cool
1 cool
1 cool
2 cool
2 cool
2 cool
Others do 3 sets of 3 round groups (all magnums however)

How did you find 41.8 of rl-16?

h4350 is one of if not the best powders out there hands down. In Georgia you will have high temps and low temps in winter, and with the temp stability it has you will have more confidence and confidence and mechanics is 90% of taking the shot.

I found the 41.8gn of RL16 by loading up 6 rds each of several powder weights. I didnt have a chrono at that time and watched for pressure signs closely. I noticed VERY SLIGHT cratering on my primers at 42.1gns and although all but the lowest charge shot really well, the 41.8 shot best. I didnt even shoot the loads that were above 42.4 ( I loaded in .3gn steps ) . I had loaded up to 43.0. Load data showed 44gn as max load. My chamber is pretty tight, so I didnt want to get near max without a chrono to verify velocity.
It was really just a safe, accurate load to shoot while I played with seating depths and fire formed brass. Now that I can run velocities, I'm going to do the quickly powder ladder to see where the node is.

 

[5.56×250]

ES and SD are primarily affected by neck tension, variation in case capacity, case fill, powder and on rare occasions primer, pretty much in that order of importance. Work on one variable at a time. Take your fire formed brass, uniform the flash holes, weight sort it and check the neck thickness, or get some Lapua brass to work with. If that doesn't cure the ES look for a powder that gives you as close to 100% case fill as possible and is the slowest powder that produces top velocities (in this case 4350 and the H version is an Extreme series powder and is at least as temp stable as RL16). If that doesn't get you the ES you want try CCI BR primers.

I've neck turned all the brass (just a half cut to even them out ). Necks consistently measure .013 now. I uniformed and beveled the flash holes too. I havent weight batched the brass yet. I am going to once fire all of it , then trim lengths before I do weights.
I'm using CCI BR primers already. I passed on lapua brass on this caliber because I already had a bunch of large rifle BR primers, and lapua only makes SRP brass for the creed. Peterson is gaining a great rep, made LRP creed brass, cost less than half of lapua, is made in Merica , and many who have compared same/same with lapua and Norma, have found Peterson brass compared well against them.

 

[Dean2]

I've neck turned all the brass (just a half cut to even them out ). Necks consistently measure .013 now. I uniformed and beveled the flash holes too. I havent weight batched the brass yet. I am going to once fire all of it , then trim lengths before I do weights.
I'm using CCI BR primers already. I passed on lapua brass on this caliber because I already had a bunch of large rifle BR primers, and lapua only makes SRP brass for the creed. Peterson is gaining a great rep, made LRP creed brass, cost less than half of lapua, is made in Merica , and many who have compared same/same with lapua and Norma, have found Peterson brass compared well against them.

Peterson is great brass. If I knew that is what you are using I would not have suggested switching. If you have already done all those steps, you are confident neck tension is even, you are measuring peed on fire formed cases, then I would say the only remaining variables to look at are case capacity and a powder change. An ES of nearly 90 is pretty big in that small a case but if you are shooting 500 yards and under I doubt you would ever be able to see it much on a target.

 

[5.56×250]

Good stuff above about getting 100 rounds thru the barrel and getting brass fire formed.
IMO, after all of that, you should try to get the SD down to 10 FPS or below. 5~7 FPS is a noble goal.
Looking at your numbers, the last one is way out of the norm and is probably caused by "climate change", so I would throw it away for now. If you use the rest of the numbers you get: Average = 2801 and SD = 15. Not toooo bad , but really more like factory ammo.
I can usually get my rounds down to to the 5~7 range by using fire formed brass without too much weight variance, annealing it each firing, and using accurate and consistent powder charges. even consistent weight and bearing surface of the bullets can help.
Standard deviation is easy to calculate in a spreadsheet. there are also SD calculators online.
Below is a link to an online SD calculator AND an excellent article on SD and just what it means and how much it matters.
For the 6.5 CM, I use H4350 for accurate target stuff, but a lot of shooters use RL16 in the 6.5 and have excellent results with it. RL16 is close to H4350 in burn rate and is supposed to be temp insensitive as well.

Online calc:
https://www.calculator.net/standard-deviation-calculator.html
PRB Blog Article on SD:
https://precisionrifleblog.com/2015/04/18/how-much-does-sd-matter/

Thanks for the links ! The load actually shoots exceptionally well for a first load on virgin brass with no real load developement. 4 different seating depths put 4 of 5 shots in the .2s in 5-10 mph shifting winds. The worst 5 shot group was .690, but that group had 4 in a .268 hole. Best 5 shot group was .450, but had one shot that stretched it vertically. 4 of those were in .240. Wind was a determining factor in those fliers in each group, im sure. It was shifting all over because one of our Ga summer thunder boomers was rolling over the hill as I was trying to get the shots in before the light show started !

 

[5.56×250]

Peterson is great brass. If I knew that is what you are using I would not have suggested switching. If you have already done all those steps, you are confident neck tension is even, you are measuring peed on fire formed cases, then I would say the only remaining variables to look at are case capacity and a powder change. An ES of nearly 90 is pretty big in that small a case but if you are shooting 500 yards and under I doubt you would ever be able to see it much on a target.

I think I got in too big a hurry and caused the rise in velocity. Like someone posted earlier , my SD was under 7 for the first 5 shots and 27? on the last 5. The last shot made the majority of the ES ! I know that one was really warm. I was sitting on the ground and I have 2 blown discs in my lower back that thought I had been in that position long enough . I should have walked away and come back in 15 mins, but pain has a way of making us do stupid stuff.

 

[YZ-80]

ES and SD are primarily affected by neck tension, variation in case capacity, case fill, powder and on rare occasions primer, pretty much in that order of importance. Work on one variable at a time. Take your fire formed brass, uniform the flash holes, weight sort it and check the neck thickness, or get some Lapua brass to work with. If that doesn't cure the ES look for a powder that gives you as close to 100% case fill as possible and is the slowest powder that produces top velocities (in this case 4350 and the H version is an Extreme series powder and is at least as temp stable as RL16). If that doesn't get you the ES you want try CCI BR primers.

I agree. Dean2 takes it a bit further than I do, but my ES numbers came down under 20 FPS consistently when I started monitoring neck tension and controlling it to about .0015. And uniforming primer pockets and chamfering flash holes. I max out on crop damage deer shots at about 400 yards, so what I try to do (at the range) is keep vertical dispersion less than .5 min (1.5") at 300 and I'm comfortable to 400 with my 6.5x47 and my 6.5-284.

 

[5.56×250]

I'm feeling pretty confident that I will have ES in the teens/20s by the time I get the brass fire formed and culled . 41.8gns does a pretty good job of filling the case. It wont shake after the bullet is seated. I'm hoping, though, that after I run a ladder on powder , that I can go up on the powder charge and get even better density . With 130 gn bullet and RL16 , I hope I can get it clicking along in the 2900fps range, so about 100fps higher than this string. If not, no biggie, I just want decent ES and tack driving accuracy. It's already shown it has plenty of promise on the second want

 

[ppoole]

See how the better prepped brass does but shoot a load .2-3 lower and see if your numbers are better. Seating depth can help tune final accuracy.

 

[SD300]

You said "Finally bought a chronograph" so I'm assuming you haven't load tested many rounds for longer ranges. My .243 loads I just let my hornady auto charge dispenser kick out, how ever many grains it's set at. Say 50 grains of superformance. I chuck it into my brass and move on. For my long range 300wm loads, I let the auto dispenser do its thing and then put it on the triple beam scale and add or take away whatever is needed to make them match grade exact. It's slow going but I typically shoot 2" and under (from prone with a good bipod) at 500 yards. If I didn't get my powder levels more spot on, my FPS would be too big to hold at long range.

 

[Dialing Long Distance]

Really, in my experience, it's hard to beat 43ish grains of H4350 with 140gr class bullets in the creedmoor. I've tried other stuff and you can find loads that'll work, but the H4350 (for me) has been very dependable for my Creed. It seems to be pretty temp stable and really consistent. Speed is great, but if it sacrifices accuracy, it can leave you with a fast miss, especially at longer distances. Just my $.02