So I’ve been pulling my hair out trying to figure out why I can’t get consistent SD’s or ES’s with a current load I’ve been working on. The gun is a RPR in 6.5 CM. I’ve done my OCW a couple times settling on a velocity node with 41.5 gr H4350 pushing 140 ELDM’s out of new (full length sized and mandrel sent through case neck) Starline brass with CCI small magnum primers. .020 headspace and a CBTO of 2.2150 which is .015 from the lands. I’m getting anywhere from 10-60 SD’s with ES’s as bad as 100fps. I’m weighing each charge with two different scales to verify. What am I missing? I will say I am using a new Caldwell chronograph and I have come to question if that’s my problem. Any thoughts would be greatly appreciated. Thanks!
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SD and ES inconsistencies
- Thread starter Gd33333
- Start date
Vivacious Stallion
Public Health Authority for the Shadow Gov
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Minuteman
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Have you shot any factory ammo through that chronograph and seen high SDs? Whats your level of experience with reloading?
As someone who bought a new magnetospeed once that was busted, it is possible the chronograph is the issue.
As someone who bought a new magnetospeed once that was busted, it is possible the chronograph is the issue.
Time to start do repeat measuring.
.020 headspace is probably a typo.
FL Sizing,
Measure base to datum on new then once fired cases.
Fired cases will probably still chamber in the RPR with a harder bolt lift.
Full length size a MINIMUM amount to get easy bolt lift.
Measure.
Mandrel,
Measurement exercise:
Fired case neck diameter,
FL Sized neck diameter Without Mandrel,
Fl Sized neck diameter WITH Mandrel.
Neck Diameter with a seated bullet.
Charge:
What is your estimate of charge accuracy?
Chronograph,
Optical accuracy is maybe 0.5 percent, at best.
Try to produce 10 rounds measuring every step with each component as equal as possible.
.020 headspace is probably a typo.
FL Sizing,
Measure base to datum on new then once fired cases.
Fired cases will probably still chamber in the RPR with a harder bolt lift.
Full length size a MINIMUM amount to get easy bolt lift.
Measure.
Mandrel,
Measurement exercise:
Fired case neck diameter,
FL Sized neck diameter Without Mandrel,
Fl Sized neck diameter WITH Mandrel.
Neck Diameter with a seated bullet.
Charge:
What is your estimate of charge accuracy?
Chronograph,
Optical accuracy is maybe 0.5 percent, at best.
Try to produce 10 rounds measuring every step with each component as equal as possible.
I have not shot any factory ammo through the chronograph. I’ve been reloading for about five years now. I’ve been thinking of trying to locate someone local with a lab radar to verify.
Yes, typo. .002 shoulder bump. What am I looking for with the different sizing/mandrel measurements? Charge accuracy of +/-.1 grn.
Chronograph position/angle errors should be consistently wrong for the same setup.
Lighting errors could change with cloud movement.
The measurement exercises are to confirm consistent, repeatable processing.
Lighting errors could change with cloud movement.
The measurement exercises are to confirm consistent, repeatable processing.
Which Caldwell chrono are you using?
Which scales are you using?
What neck tension are you using?
Are you annealing your cases?
It could be that your load in that gun doesn't like magnum primers. Have you tried any other primers?
Have you tried measure case volumes (like ~10) to get an idea of their volumes and how consistent they might be?
How many rounds down the barrel?
Your post said new brass, use the same process and load with once fired brass from your chamber and see what the results are.
I'll list a few things below, but they would not be solely (or even primarily) responsible for a mid-double digit SDs. There is something dramatic going on with your process, so...
1) Please post your full reloading process
2) Starline is just okay brass. If you can get some Lapua, get some Lapua.
3) Your SDs are bad, but they get exasperated with new brass. Someone else mentioned that you should measure them against once-fired.
4) How many rounds through the rifle?
5) When and how do you clean the rifle?
6) Have you cleaned the brake?
The G2 chrono
Running the FA Intellidropper and cross referencing with FA precision electronic scale
Running a .262 mandrel for neck tension
No need to anneal as they are new
Haven’t tried standard primers so could most definitely try that
I have not measured case volume
About 300-400 rounds
I plan to do this and am hoping to see a difference. Haven’t had much luck finding any information regarding new brass and possible affects on SD’s. Have you had similar issues with new brass?
Ok here goes:
With new brass, I full length sized without expander ball and then ran a .262 mandrel through neck. I trimmed and deburred any over length cases. Primed with hand primer. Dispensing powder with FA Intellidropper and cross referencing with FA precision electronic scale (both +/- .1 grn accuracy). Measured every CBTO while bullet seating to verify within .001.
This is the first I’ve tried Starline so I’m hoping that’s not the problem. Was hoping it would be alright as Lapua is twice the price.
I plan to load some once fired exactly the same to see if there is a change.
Probably 300-400 rounds
Clean every 100 rounds or so
Break is brand new Fat Bastard
I wouldn't expect to get single-digit SDs with what you're doing, but it shouldn't be driving the numbers you're seeing either.
Lapua could very well last twice as long, and it is that much better. I use Starline for some pistol-caliber reloading, but would never use it for precision rifle.
I will be surprised if it suddenly drops to anything resembling the "good" range, but it should go down quite a bit.
Likely not enough to have a sizeable carbon ring form, but not out of the question either. If you have a borescope, it would be worth taking a look.
What is your cleaning process?
Good brake.
All of the above advice, plus...
Have a good hard look at your primer seating and the firing pin assembly.
Have a good hard look at the spring.
Make sure the rig has no issues or irregularities with the firing pin fall or protuberance.
Uneven primer seating or uneven firing pin strike can cause as many or more problems as the ammo.
If at all possible to try some ammo from a reputable source for reference, it might tell us if the rig is more worth investigating than the ammo, but sometimes we are still left with questions.
To look at this the other way, if the rig does produce good SD/ES values from some different ammo, then we at least know to focus on your loads and not the rifle. ES values of 100 from small samples are very poor, so at least we are not in a marginal situation.
Good Luck and don't give up.
Have a good hard look at your primer seating and the firing pin assembly.
Have a good hard look at the spring.
Make sure the rig has no issues or irregularities with the firing pin fall or protuberance.
Uneven primer seating or uneven firing pin strike can cause as many or more problems as the ammo.
If at all possible to try some ammo from a reputable source for reference, it might tell us if the rig is more worth investigating than the ammo, but sometimes we are still left with questions.
To look at this the other way, if the rig does produce good SD/ES values from some different ammo, then we at least know to focus on your loads and not the rifle. ES values of 100 from small samples are very poor, so at least we are not in a marginal situation.
Good Luck and don't give up.
You might be right, that this is the problem, or some part of the problem. Best thing to do there is check it against someone else's chrono (preferably, a radar type).
Using these two scale together as you've described wouldn't be responsible to that much inconsistency. Just don't expect single digit SD's, though you might get some with low round counts.
That really doesn't tell you what your neck tension is do to an unknown amount of springback. Need to measure the necks before seating then after seating.
OK. New brass can certainly contribute to the variations you're seeing . . . even after running a mandrel through them. The interference between the neck and bullet surfaces can be a lot and reduced some using some kind of lube to ease that interference.
You might be surprise how a "standard primer" might help a lot with consistency. It's worth a try.
Any time you get new brass, it's a good idea to measure some case volumes as there can be significant differences between lot. Hopefully, you not mixing lots.
Barrel should be stable by now; sometimes it take 150 to 200 rounds. Just be thorough in check the chamber and bore that nothing unusual is going on there. And as RegionRat suggests, it good to also check your firing pin and bolt assembly.
What would you recommend for single digit SD’s? Is there additional steps I should be doing? I use the same process for my 6.5PRC and repeatedly get single digits. I will say that I do use Lapua brass for those though.
As far as cleaning, I run a copper cleaner through the bore, followed by a brass brush and then clean patches until dry. Then another wet patch that sits overnight. Dry patches until they come out clean and then finish with a lubricant.
Thanks
So measuring case neck before and after seating tells me what exactly? All 200 pieces of brass are same lot. I’ve thought about trying a dry lube and will definitely give the regular primers a shot. Thanks
Good call with comparing to factory reputable ammo to make sure it’s not the gun. I will try that. As far as primer seating, do you think I need to seat primers differently? I know they make units where you can set your primer depth. Is that what you’re referring to? Thanks for the help
I have no trouble getting very good numbers with Starline in 6.5cm so I very much doubt it's the brass but brass fired in your chamber and bumped consistently will give you better SD.
You need to use fired brass. Also make sure you have a good chamfer, consistent bump, ect.... and are getting good readings on your chrono. I love me some lapua but the Starline 6.5cm I've tested a good bit and it's done very very well for consistent SD and low SD. Now mine is all LRP so perhaps there's a difference there. Lapua is the better brass but case capacity consistency is good for Starline I've shot and tested and SD is great for them. All of mine is at least a few years old so perhaps there's a difference in the new? I'd bet if you're careful and use fired brass you will see those numbers go in half. Check the difference in your fired brass vs virgin and check and see how consistent your fired brass is in size.
My process starting from post-firing:
1) Deprime
2) Clean in ultrasonic
3) Anneal
4) FL Size
5) Neck lube with moly
6) Mandrel
7) Trim
8) Neck lube again
9) Charge
10) Seat with an arbor press and LE Wilson seaters
Three things:
1) If you're not using something that attacks carbon, then it is likely you've got some buildup going that could be causing what you're seeing. Get a good carbon cleaner and run patches through using the process I outline below - but let sit longer. Or you could plug the end of the barrel, stand it up with muzzle down, fill it with some carbon solvent, and let sit overnight, then do the process.
2) I only use brass brushes when absolutely necessary. If you scrub a barrel enough with them, it will negatively affect the barrel. Same thing with abrasive cleaners.
3) You might be getting some copper buildup as well. The process you're using will get some copper out, but certainly not all.
My process:
1) Run two wet patches soaked in Boretech Eliminator - I mean SOAKED
2) Let sit for 15 minutes or so
3) Run a couple dry patches through
4) Repeat the above steps until you get only very light blue (or none) and very light/no carbon.
Then:
5) Clean behind the lugs
6) Mop the chamber
If I'm fighting carbon, then putting patches around a used nylon brush (vs. a jag) will put more uniform pressure against the barrel and seems to be more effective in pulling the carbon out.
If I'm fighting a carbon ring in the chamber, then I put in a +1 size nylon brush (e.g. for my 300, I use a 338 brush) into the chamber with a patch around it soaked in carbon cleaner. The bigger brush + patch will be too big to get into the barrel, so stops at the end of the chamber. I let that sit for a long time (overnight usually), then twist it in the chamber. Repeat as necessary. Carbon rings are a bitch to remove, but I've found this to be at least somewhat effective.
Lastly, I just reread your original post. You mention finding a velocity node. I do a lot more ELR than anything else, so I care about SDs more than someone doing PRS, as an example. My definition of a velocity "node" is one that gives me the best SDs, not the best group size. Once you find that SD sweet spot, then tune for group size using seating depth.
On my 300's new barrel, I found a velocity range that's delivering good SDs, then on my last trip to the range I did a seating depth test (then validated at 500 yards with 5 shots - then 850 with a bunch - no grouping pic because it was a frikking bog out there and I couldn't get to the target):
Put it on paper and see if it shoots to your satisfaction and work from there.
Numbers on a digital screen don’t equal results.
Numbers on a digital screen don’t equal results.
those numbers on a screen matter a ton if you're shooting at distance (800+ yards)
And if they don’t bear out the “good” with real tangible results then what good are they?don't need to if the numbers on the screen are good
those are the results. a low sd group with less precision at 100 yards will shoot better at a distance than a higher sd group with better precision at 100 yards.
nearly none of us are shooting enough groups for their to be statistical relevance when shooting a bunch of 100 yards groups. No I am not saying a .5 inch group vs a 3' group will shoot the same at distance but .3" group with high sd will be outperformed by .5" group and low sd at distance.
SD and ES are connected at the hip. They aren't independent of one another. One won't do something on target that another will such as smaller groups vs dropping fewer points.
Whatever your true SD is, your ES will be six times that amount for 99.7% of your shots. The other .3% will consist of increasingly larger ES, but obviously will be pretty rare since it's 0.3%.
Your graph is for a large sample of a process "IN CONTROL".
While we HOPE that our reloading and shooting processes are in control,
any rogue variable introduced will skew that curve.
Bullet making is a process.
Case making is a process.
Primers have their own distribution (which may or may not have an impact).
Powder charge, the one thing we try to control is a process.
Independently they may skew the final process of making rounds.
While we HOPE that our reloading and shooting processes are in control,
any rogue variable introduced will skew that curve.
Bullet making is a process.
Case making is a process.
Primers have their own distribution (which may or may not have an impact).
Powder charge, the one thing we try to control is a process.
Independently they may skew the final process of making rounds.
He’s smug and condescending but the graph is true for all stats. That’s just how sd works. You’re pretty close though - keep your sd and es low and it will shoot better at distance.
It’s best not to engage with him he doesn’t try to help people just talk over them so he can feel smart for once
That doesn't change how SD and ES work. There's a reason no one outside of the firearms community uses ES. It's all but worthless and SD tells you about where your ES is going to be.
Your scenario of "sd is smaller groups but ES is more points" isn't possible. It's not the way it works.
Adding thoughts to post #16: Primer seating....primer is seated correct when ,after firing and deprimed ,the primer pocket will look like 3 perfect pizza slices . Iffin the primer pocket is blacked all over the bottom....it ain't right imo.
I've used a hand primer, but couldn't get consistent results described above. "Shootin Buddy" gave me a rcbs ram primer and consistency improved greatly,resulting in a lot less "what da hell " happened there moments.All the " little" things done during handloading ,that some think unnecessary, add up to more consistent ammo ,for me.......and that's what we are trying to accomplish, right?
Last thought: as stated in noted post, if yo firing mechanism is out of wack.......you gonna be chasing your tail,until it is corrected.
I've used a hand primer, but couldn't get consistent results described above. "Shootin Buddy" gave me a rcbs ram primer and consistency improved greatly,resulting in a lot less "what da hell " happened there moments.All the " little" things done during handloading ,that some think unnecessary, add up to more consistent ammo ,for me.......and that's what we are trying to accomplish, right?
Last thought: as stated in noted post, if yo firing mechanism is out of wack.......you gonna be chasing your tail,until it is corrected.
Deleted post to give better explanation.
A production limit is absolutely *NOT* the same as extreme spread. A production limit is a limit of what is acceptable. Extreme Spread is simply the highest and lowest value in a sample or population.
By definition, a production limit can't be extreme spread. If it was extreme spread, then you wouldn't need a limit as extreme spread would encapsulate all the the values.
For example, let's say you are manufacturing product X. You make 1,000 pieces. You decide to set your production limit as two standard deviations. Anything larger than that is not an acceptable product. That is definitely not your extreme spread. Your extreme spread would be three standard deviations.
In this case, you would have 95% of product X that is acceptable.....and 5% that is not. The 95% isn't your Extreme Spread (the 95% is your production limit). The 5% is your Extreme Spread.
A production limit is absolutely *NOT* the same as extreme spread. A production limit is a limit of what is acceptable. Extreme Spread is simply the highest and lowest value in a sample or population.
By definition, a production limit can't be extreme spread. If it was extreme spread, then you wouldn't need a limit as extreme spread would encapsulate all the the values.
For example, let's say you are manufacturing product X. You make 1,000 pieces. You decide to set your production limit as two standard deviations. Anything larger than that is not an acceptable product. That is definitely not your extreme spread. Your extreme spread would be three standard deviations.
In this case, you would have 95% of product X that is acceptable.....and 5% that is not. The 95% isn't your Extreme Spread (the 95% is your production limit). The 5% is your Extreme Spread.
No one cares about your rudimentary understanding of stats. No one is impressed by you conflating a non-issue to feel smart.
I care
I do agree though.....using production limits and/or acceptable ES is a good thing to incorporate into your load development.
You decide that say.....7fps is your maximum acceptable SD.
You can do a couple things now.
-If you're shooting 5 shot strings to test, you can run sims or calculate the max SD that is acceptable for a 5 shot string. It would be somewhere in the neighborhood of 12 fps.
-You can use and ES of 42fps (6*7)
Now you have two production limits for your load development. If at anytime during a 5 shot string, your ES is over 42, you stop shooting that combination of components and move to the next.
Once you shoot all your 5 shot strings, you can eliminate the combinations that were over the ES, and you can eliminate the combinations that were over 12sd. You wouldn't throw those 12sd strings in the trash, since they are within the limit of what's significantly possible with a 7sd and 5 shot strings.
Then you go back and load up more of each combination that were under the 42es and the 12sd. You then do the exact same thing with your production limits and the combinations that made it past the first round. And continue the process until you only have a few combinations to choose from for your ammo going forward.
If you consider that velocity has something to do with elevation, faster hits higher, slower hits lower,
an estimate of elevation vs velocity would be one way of setting acceptable upper and lower limits.
If for example, 25 fps gives you 1/2 MOA variance at some range, say 600yd, puts you right on the 9/10 line,
a 65 shot string (F-Open),
52@ 2950fps, 13@ 2925, SD of 10.1, ES 25, 1/2 moa just from velocity.
61@ 2950fps, 4 @ 2910, SD of 9.69, ES 40, 4 shots greater than 1/2 moa (4 lost points?)
63@ 2950fps, Just 2 @ 2900, SD 8.7, ES 50, 2 shots outside 1/2 moa for sure.
(primer weight outliers slipped into your load?)
Single digit SD and maybe a clean some other day
Not real life to have shots at exactly the same velocity, but ES limits sounds like a good idea.
an estimate of elevation vs velocity would be one way of setting acceptable upper and lower limits.
If for example, 25 fps gives you 1/2 MOA variance at some range, say 600yd, puts you right on the 9/10 line,
a 65 shot string (F-Open),
52@ 2950fps, 13@ 2925, SD of 10.1, ES 25, 1/2 moa just from velocity.
61@ 2950fps, 4 @ 2910, SD of 9.69, ES 40, 4 shots greater than 1/2 moa (4 lost points?)
63@ 2950fps, Just 2 @ 2900, SD 8.7, ES 50, 2 shots outside 1/2 moa for sure.
(primer weight outliers slipped into your load?)
Single digit SD and maybe a clean some other day
Not real life to have shots at exactly the same velocity, but ES limits sounds like a good idea.
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This. What does it show on paper at 400-500? What the OP is describing is watching porn instead of having sex with the willing woman in front of you.
52@ 2950fps, 13@ 2925, SD of 10.1, ES 25, 1/2 moa just from velocity.
61@ 2950fps, 4 @ 2910, SD of 9.69, ES 40, 4 shots greater than 1/2 moa (4 lost points?)
63@ 2950fps, Just 2 @ 2900, SD 8.7, ES 50, 2 shots outside 1/2 moa for sure.
(primer weight outliers slipped into your load?)
Single digit SD and maybe a clean some other day
...wouldn't the ES be double that, since you'd expect some to be equally higher than average?
Or is this just a theoretical "hey where did those spare kernels on my loading block come from" scenario?
It makes more sense to me, to punch your speed and SD into a hit probability calc and recognize that scenario number two still hits within a half MOA 69% of the time and almost all within 1 MOA.
The difference between 5sd and 10sd at the barrel at 1k yards for my 300 win mag is 100% vs 84%.
bisonballistics.com
Hit Probability Calculator
A free hit probability calculator for long range shooting.
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Measuring before and after gives you a measurement of the "neck tension" without considering the neck wall thickness. Like, if the before measurement is .280" and after seating it measures .282", then you've got .002" "neck tension".
