New Reloader, Huge Velocity Drop From a Change in Brass?

[Ryan3344]

New reloader here. I have started load development for a Tikka T3X in 6.5 CM. For my first batch I ladder tested 30 cartridges in 0.2 grain increments, working from 85% of max, to max. Components were as follows:

Die: Hornady Custom
Primer: CCI BR-2
Brass: Once fired Winchester white box factory, full length resized only bumping the shoulder .002"
Powder: H4350
Bullet: Hornady 143 grain ELD-X
COL: 2.825

I did not trim or anneal any of the brass, and it was all within headspace and trim length parameters. Results were great with velocities ranging from ~2380 at 85% to ~2750 at 100%. I found accuracy nodes consistently 1 grain apart, around the XX.9 mark (39.9, 40.9, etc.). I found a very accurate node at around 96% of max, and was predicting I would hit another at 41.9 grains, just slightly above the max of 41.5.

After cleaning and inspecting that same brass I was seeing what looked to me to be the start of head separation (going to post some pictures in another thread for peer review and opinions as I'm new) so in the interest of safety and using better components, I switched brass for my next test. I switched to brand new Hornady brass, and wanted to do another sort of ladder test. I started the shot string at 95% of max (so I could shoot that node at 96% again, and start below max since switching a component) increasing by the same 0.2 grains per cartridge.

Once I got to max charge weight, I switched to groups of three at each weight, increasing by only 0.1 grains of powder between groups. I did this as an extra safety factor as I would be pushing past max and wanted 3 brass at each increment to inspect for pressure signs. It also allowed me to start gathering a very small sample of grouping information that I thought might help me dial in my final charge weight as I could see a small sample group size and SD etc.

Components of this second group were:

Die: Hornady Custom
Primer: CCI BR-2
Brass: Brand new Hornady brass, ran through sizing die to uniform the neck without touching the shoulder at all
Powder: H4350
Bullet: Hornady 143 grain ELD-X
COL: 2.825

This is where things get a little strange and I am at a loss. My second string of 30 cartridges all had very similar POI to my first string, had some incredible groups at the nodes, but my velocity is a full 500-550 fps slower than the first string. The only variable I changed was the brass, and I can't believe that alone would create such a dramatic shift in velocity. My range on this string was 2060 at 95% to 2170 at 101.5% of max. No pressure signs and very little recoil when firing.

Plan is to resize these now fire formed brass as described with my first string, then load up another 30 at the same charge weights as my second string, and reshoot to see if the velocity comes back. I would love any insight or explanation as to where my velocity went if someone has any.

TIA

 

[Rugger7622]

Someone with more experience than me will chime in, I only reload 1,000ish rounds a year, but I can't see anything in your numbers that would lead to a 500 fps drop, with the same amount of powder in the case. For the most part, once/twice shot brass allows you to add just a bit more powder.

Anything wrong with the crono you shot it over or the way you dropped the powder? You could grab Gordan's reloading software - it's free, and run some powder reduction ladders in the software to give you and idea of where it should be and how much less powder if would take to drop the base 500fps.

I'll follow along to see what other member thinks as well.

 

[steelheadmike]

It's not the brass. Something got royally screwed up in your process or your chrono was on the fritz. I'd have a hard time believing that your POI was the same with that low of velocity.

Instead of loading 30 again, save the bullets and just shoot a couple at a time. There are significant issues that need to be resolved before loading a bunch more.

I'll see MAYBE 25-30 fps swing in different brass using same recipe.

 

[WeiserBucks]

Either your powder is undercharged or your chronograph shit the bed.

 

[Ryan3344]

It's not the brass. Something got royally screwed up in your process or your chrono was on the fritz. I'd have a hard time believing that your POI was the same with that low of velocity.

Instead of loading 30 again, save the bullets and just shoot a couple at a time. There are significant issues that need to be resolved before loading a bunch more.

I'll see MAYBE 25-30 fps swing in different brass using same recipe.

I had same thoughts regarding POI if velocity was that different. Chronograph is a brand new Garmin only used a handful of times. I did restart it after the first 3 shots of the second string as I was worried it might be on the fritz, but it continued to give me the exact same data as I continued up through the loads.

Powder scale is a brand new Hornady digital scale, calibrated with the included weight before charging brass. I'm positive I charged the brass correctly, as long as the scale was functioning properly. I didn't bring any factory loads out to shoot to compare felt recoil, velocity, etc.

Thinking of loading up like 5 at around 95% of max and retesting them alongside some factory to verify the chronograph.

 

[steelheadmike]

I had same thoughts regarding POI if velocity was that different. Chronograph is a brand new Garmin only used a handful of times. I did restart it after the first 3 shots of the second string as I was worried it might be on the fritz, but it continued to give me the exact same data as I continued up through the loads.

Powder scale is a brand new Hornady digital scale, calibrated with the included weight before charging brass. I'm positive I charged the brass correctly, as long as the scale was functioning properly. I didn't bring any factory loads out to shoot to compare felt recoil, velocity, etc.

Thinking of loading up like 5 at around 95% of max and retesting them alongside some factory to verify the chronograph.

Like WeiserBucks said, there's only two possibilities.

I've only been reloading for a few months so take what I say with a grain of salt. Keep a second scale around just to do a quick confirmation of charges whenever I start a batch. It doesn't have to be too fancy but just good enough to confirm that you're primary scale is not malfunctioning. Also, pay close attention to your case fills. You'll get a pretty good idea of how full a case will be with a given powder. You won't be able to see a grain or two of difference, but you'd be able to see a difference that you cause a 500fps drop.

Grab a box of factory ammo or try to use another chrono. My hunch is that the chrono is having issues.

 

[S.Clancy]

I think the most likely is a chrono error. You could have zeroed your scale out with something on it causing it to spit out low charge weights.

 

[wind gypsy]

I once accidentally loaded a 300 WM with 66 grains rather than 76 grains and had an immediate WTF moment at range when i saw velocities so I stopped shooting them. That's about the only thing i can surmise happened, loads at 30 grains vs 40? Or your chrono is on the fritz, or you soaked your h4350 in water for a day before loading it.. Those speeds are way the eff off and if accurate they are possibly dangerous. I would not continue shooting 2000 FPS loads unless done intentionally with a powder known to perform safely at reduced velocities.

 

[Jebel]

I agree that a 500 fps variance puts you outside the realm of component swapping changes and signals something wildly off like charge or chrono. If your POI was the same, seems more like chrono.

As a reloading aside, don’t expect FF brass results to compare with virgin brass. Apples and oranges.

Also an aside, you stated the same powder and didn’t note a change in lot or anything else so we assume no difference.

 

[Ryan3344]

I think the most likely is a chrono error. You could have zeroed your scale out with something on it causing it to spit out low charge weights.

THIS.

I think I made a calibration error with the scale, just went to confirm and that seems to be the case. I set the weight on the scale for just a brief couple seconds before I was supposed to, realized and removed it. Then, put it back on at the scale at the proper step and the scale passed the calibration so I moved on without thinking about it, or (very stupidly I'm now realizing) verifying with the included weight after calibration.

I just tested incorrectly calibrating the scale as was done when loading the bullets, and was coming in significantly heavier than the calibration weight when verifying after calibration. I must have been getting false readings and under charged the brass.

I was keeping an eye on case fill and honestly did think they were a little low, but I'm so new to reloading I trusted the scale over my own experience, as there isn't enough experience to trust yet.

Very important lessons learned for a new reloader. Thankfully with no damage to shooters or equipment. Plan is still to reload 5 PROPERLY, and compare them to factory to verify chronograph etc.

Thank you to everyone who chimed in with some help. Will report back one final time after retesting but I think we found the issue.

 

[Ryan3344]

I agree that a 500 fps variance puts you outside the realm of component swapping changes and signals something wildly off like charge or chrono. If your POI was the same, seems more like chrono.

As a reloading aside, don’t expect FF brass results to compare with virgin brass. Apples and oranges.

Also an aside, you stated the same powder and didn’t note a change in lot or anything else so we assume no difference.

Thanks for the info and tips!

I didn't expect the virgin brass to perform exactly the same and was using this ladder test to fire form it so I could use the then FF brass to start group testing and fine tuning the load afterward. I expected some differences to velocity or POI, etc. I couldn't believe the drop in velocity however, and figured I needed to turn to those with more experience than me to help identify where the error could be. I assumed I must have made one along the way but couldn't pin point it. But I think it is all figured out now, sloppy scale calibration and lessons learned.

Powder and primers were out of the exact same container as the first string. No changes there at all, only brass (and poor scale calibration).

 

[S.Clancy]

THIS.

I think I made a calibration error with the scale, just went to confirm and that seems to be the case. I set the weight on the scale for just a brief couple seconds before I was supposed to, realized and removed it. Then, put it back on at the scale at the proper step and the scale passed the calibration so I moved on without thinking about it, or (very stupidly I'm now realizing) verifying with the included weight after calibration.

I just tested incorrectly calibrating the scale as was done when loading the bullets, and was coming in significantly heavier than the calibration weight when verifying after calibration. I must have been getting false readings and under charged the brass.

I was keeping an eye on case fill and honestly did think they were a little low, but I'm so new to reloading I trusted the scale over my own experience, as there isn't enough experience to trust yet.

Very important lessons learned for a new reloader. Thankfully with no damage to shooters or equipment. Plan is still to reload 5 PROPERLY, and compare them to factory to verify chronograph etc.

Thank you to everyone who chimed in with some help. Will report back one final time after retesting but I think we found the issue.

I always shake the loaded cartridge before putting it in the box, you can catch low charges (or even worse, no charges) that way pretty easy.

 

[Harvey_NW]

Since you're asking, couples things of note here:

Powder scale is a brand new Hornady digital scale

This was my first guess reading through the comments, the cheaper (Hornady, Lee, RCBS, etc.) digital scales are not very accurate and tend to drift +/- .1gr usually at best. If using a digital and trying to be precise (as it seems you are), I suggest at least double checking on a reliable beam before charging. I use a Chargemaster and set it for .1gr low and trickle up on a beam. I'd say about 50% are on, 45% low by .1ish, 5% over.

I found accuracy nodes consistently 1 grain apart, around the XX.9 mark (39.9, 40.9, etc.). I found a very accurate node at around 96% of max, and was predicting I would hit another at 41.9 grains, just slightly above the max of 41.5.

This isn't a thing, what you're observing is random distribution of small sample groups that have up to 70% variability. If you reshoot that test, it's likely that all the "nodes" will be at different charge weights than the first test. Up your sample size and the sinusoidal results go away and the groups start to even out. If you enjoy tinkering and banging away testing, by all means continue. But if you want to "develop" accurate loads as fast as possible, do your work up/pressure test, load 10 at a safe charge, and shoot a group at a single POA. If it's acceptable, that's your load. If it's not, swap powder or bullet and rinse and repeat. You can prove this by testing it, take the best and worst groups from your OCW test, load 10 of each and compare group size. They'll likely be within +/- 30% of each other (with a perfect test, no "pulled" shots). With a good rifle and load I've found 10 shot groups usually repeat with pretty low variability.

Plan is to resize these now fire formed brass as described with my first string, then load up another 30 at the same charge weights as my second string, and reshoot to see if the velocity comes back. I would love any insight or explanation as to where my velocity went if someone has any.

Formed brass will typically show pressure faster than new brass, it's theorized that some of the energy is expended when forming the new brass, so it would be worth doing a short pressure test with the formed before going full tilt. I find I usually have to back off 1.5gr or so from "max" on new brass to get back to safe with formed and properly resized brass.

Hope that helps

 

[SDHNTR]

THIS.

I think I made a calibration error with the scale, just went to confirm and that seems to be the case. I set the weight on the scale for just a brief couple seconds before I was supposed to, realized and removed it. Then, put it back on at the scale at the proper step and the scale passed the calibration so I moved on without thinking about it, or (very stupidly I'm now realizing) verifying with the included weight after calibration.

I just tested incorrectly calibrating the scale as was done when loading the bullets, and was coming in significantly heavier than the calibration weight when verifying after calibration. I must have been getting false readings and under charged the brass.

I was keeping an eye on case fill and honestly did think they were a little low, but I'm so new to reloading I trusted the scale over my own experience, as there isn't enough experience to trust yet.

Very important lessons learned for a new reloader. Thankfully with no damage to shooters or equipment. Plan is still to reload 5 PROPERLY, and compare them to factory to verify chronograph etc.

Thank you to everyone who chimed in with some help. Will report back one final time after retesting but I think we found the issue.

This is why I always double check my electronic scale with a few charges per batch on the balance beam.

 

[Ryan3344]

This is why I always double check my electronic scale with a few charges per batch on the balance beam.

I'm quickly learning this - haha. Got a good sale price on a Hornady autoloader pro so I'm upgrading my scale game and that will give me two so I'm able to verify between them, not to mention save time measuring powder. Going to pick up a balance beam too eventually, hard to beat analog sometimes.

It's my own damn fault that I calibrated it wrong and I know that but it's a little misleading when the scale says "pass" after calibration, and it is in fact way off. Should have double checked of course, but just trusted the device.

 

[Ryan3344]

Since you're asking, couples things of note here:


This was my first guess reading through the comments, the cheaper (Hornady, Lee, RCBS, etc.) digital scales are not very accurate and tend to drift +/- .1gr usually at best. If using a digital and trying to be precise (as it seems you are), I suggest at least double checking on a reliable beam before charging. I use a Chargemaster and set it for .1gr low and trickle up on a beam. I'd say about 50% are on, 45% low by .1ish, 5% over.


This isn't a thing, what you're observing is random distribution of small sample groups that have up to 70% variability. If you reshoot that test, it's likely that all the "nodes" will be at different charge weights than the first test. Up your sample size and the sinusoidal results go away and the groups start to even out. If you enjoy tinkering and banging away testing, by all means continue. But if you want to "develop" accurate loads as fast as possible, do your work up/pressure test, load 10 at a safe charge, and shoot a group at a single POA. If it's acceptable, that's your load. If it's not, swap powder or bullet and rinse and repeat. You can prove this by testing it, take the best and worst groups from your OCW test, load 10 of each and compare group size. They'll likely be within +/- 30% of each other (with a perfect test, no "pulled" shots). With a good rifle and load I've found 10 shot groups usually repeat with pretty low variability.


Formed brass will typically show pressure faster than new brass, it's theorized that some of the energy is expended when forming the new brass, so it would be worth doing a short pressure test with the formed before going full tilt. I find I usually have to back off 1.5gr or so from "max" on new brass to get back to safe with formed and properly resized brass.

Hope that helps

Thank you for taking the time for the write up and to include all the tips, I appreciate it!

Very good advice on the beam, I am looking for precision and like to make sure my details are dialed and very repeatable. I got a good deal on a Hornady pro autoloader and am going to add a beam as well.

Very interesting, thank you! So what you have outlined is sort of my plan. I used a ladder test to basically pressure test and to also try to find those nodes as a starting point for group testing. Then I am planning on taking the 2 "nodes" at the highest safe charge weights and group test them comparing multiple groups in 0.1 grain increments around the center of that node (say maybe 5 groups, 2 below, the "node" itself, and 2 above) to see which group performs best. Each group would be on it's own target of course, with the same POA for each group. Then compare group size and velocity info and SD etc. and pick the best charge weight from there. Then load up another batch and start stretching them out and verifying the ballistics calculator and observing groups at distance, potentially with more than one charge weight if there is a sort tie in my results.

I understand this is likely the long road to get where I'm going, and wasting some components, but I am enjoying the process and going the long way just to dial my process and learn as much as possible along the way. It also gives the wife and I an excuse to shoot a little more so nothing wrong with that - haha. I also sort of like the idea of "exhausting" a bullet and powder combo to see just how accurate I can get it before switching out one of those components. That all being said, I appreciate all of the advice and I'm quite sure once I get rolling and learn more I'll be looking for a faster, less wasteful way to determine optimal loads for given bullet/powder combos.

Let me know if anything I've outlined above seems totally whacky, or if I should get somewhat decent results despite taking the scenic route to get there.

Great info on the brass as well. Makes sense some of those pressure forces would be eaten up FF the brass. I had intended to always back down a bit and pressure test back up whenever changing any component, but this is just more reason to.

 

[dukeball33]

I'm quickly learning this - haha. Got a good sale price on a Hornady autoloader pro so I'm upgrading my scale game and that will give me two so I'm able to verify between them, not to mention save time measuring powder. Going to pick up a balance beam too eventually, hard to beat analog sometimes.

It's my own damn fault that I calibrated it wrong and I know that but it's a little misleading when the scale says "pass" after calibration, and it is in fact way off. Should have double checked of course, but just trusted the device.

The pan weight with the scale won't change either... either write it down or remember it and after calibrating the pan should weigh, for instance, 196.9 grains.

 

[Harvey_NW]

I understand this is likely the long road to get where I'm going, and wasting some components, but I am enjoying the process and going the long way just to dial my process and learn as much as possible along the way. It also gives the wife and I an excuse to shoot a little more so nothing wrong with that - haha. I also sort of like the idea of "exhausting" a bullet and powder combo to see just how accurate I can get it before switching out one of those components. That all being said, I appreciate all of the advice and I'm quite sure once I get rolling and learn more I'll be looking for a faster, less wasteful way to determine optimal loads for given bullet/powder combos.

Let me know if anything I've outlined above seems totally whacky, or if I should get somewhat decent results despite taking the scenic route to get there.

Not really. Been there, done that, lol. Just reiterating that nodes don't exist, and those tiny powder charge or seating depth changes aren't actually making an improvement to the precision of the load. Ballisticians have stated that dropping powder charge can decrease dispersion, but it's usually not worth the sacrifice in velocity. So I guess my point is there is no "how accurate I can get it", it is what it is. I know this is contradictory to all the traditional dogma regurgitated by all the facebook snipers that have cherry picked 3 shot groups of their 1/4 MOA Ruger Americans, but Hornady, Bryan Litz/Applied Ballistics, Shoot2Hunt, etc. all have plenty of information out there to substantiate it.

 

[cq0302]

I think everyone has pretty much said it but you have to calibrate an electric scale everytime. I also double check against a second scale. Also, leave your electric scale plugged in several hours before starting. I leave mine plugged in all the time


Sent from my iPhone using Tapatalk

 

[solarshooter]

I understand this is likely the long road to get where I'm going, and wasting some components, but I am enjoying the process and going the long way just to dial my process and learn as much as possible along the way.

No offense intended here - it's not just the long road, it's totally delusional. Once you understand the statistics, the method you are describing here is literally like having someone read your palm and tell you your fortune, drawing tarot cards, looking for faces in burnt toast, etc, etc. You are not LEARNING anything by doing testing with small groups, you are only reinforcing an incorrect understanding of statistics. I know because I wasted about 5 years and maybe 10k rounds of ammo doing it, before I realized I wasn't "tuning" shit.

You have to realize, you have accepted a very elaborate theory of accuracy and tuning as truth (nodes, small changes in powder, seating depth, groups at distance, etc) without disproving the much more simple explanation (random noise due to variations of small samples). Any time anyone takes time to disprove this null hypothesis, they come to the conclusions that I and @Harvey_NW have stated here.