Load development or not?
- Thread starter smokinbobf4
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It's not the mandrel. Like you said . . . it's "only three shots". Though, a particular neck tension can make a difference. Now you'll have to test again to verity.
Yeah so, without the mandrel treatment sd was 7.7, awesome, good enough for me. Reloaded nine more just like them. Not so Bueno.It's not the mandrel. Like you said . . . it's "only three shots". Though, a particular neck tension can make a difference. Now you'll have to test again to verity.
three in that one on the right.
I'm out of prepped brass so that's all for today.
Primers can make all the difference. For example . . .
Just a few weeks ago, I picked up some Remington 9.5's for a really good deal and thought I'd just use them for fireforming some brass. Out of curiosity, since I've never used them before, I loaded up 25 rounds just to see if the velocity difference (if any) due to reports of them being hotter than Fed's and CCI's. Criminy! Average velocity was higher than what I normally get by ~20fps, but it was the inconsistency the floored me. For the 25 rounds I got an SD of 33 fps and and ES of 97fps. What the . . .??? I've never had loads do that poorly, even though I wasn't using my best brass. Then I loaded up 10 rounds of my best loads that work really well, where I typically get mid single digit SD's, but the only difference being the Remington primers. Velocity was still ~20 fps faster than normal and the SD was 14.2 and the ES was 41. The Remington primers I've got SUCK! I guess I'll still use them for fireforming though.
Also few weeks ago I got some .308 Alpha brass and decided to fire form them. I loaded up 10 with my favorite load using CCI400's just to find their case volumes. Out of the 10 I got 3 pierced primers. That too is a first for me. Apparently the larger flash holes that Alpha brass has puts more pressure of the thinner 400's cups. Followed up with CCI 450's in 10 more and they performed well, giving me 5.3 SD and a 16 ES, and . . . the two 5 round groups were at .435" (at 100 yds). Because those 10 did so well, I loaded up the 80 remaining cases with the same load. Yesterday, 80 rounds fired and chronoed with an SD of 6.2 and an ES of 29.
Choosing the right or wrong primers can make a difference.
Lots to unpack here, and, coincidentally, part of a video I'm doing voiceover for as I write this.
To talk the key points in what you wrote:
- You tried a different primer to see if they are hotter than others.
- They were inconsistent - high ES/SD
- In another scenario, you got pierced primers trying a new brass (Alpha) that has larger flash holes
Let's talk the primer difference thing.
- It is quite possible that the Rem 9.5s are just that crappy compared to CCIs, though I doubt that's the case - those numbers are atrocious.
- More likely, the Rems are indeed "hotter" than the others you've tried, which means they are igniting the powder more quickly, which will force everything to peak pressure sooner, which increases burn rate of the powder, which in turn drives up pressure more, etc.
- It is likely the reason your numbers went to hell. Your velocity changed just a little bit, but, more importantly, the new primers drove your peak pressure to hit significantly earlier. This changes how your bullet accelerates (quicker), how it engages the lands (sooner and harder), and the pressure behind it as it does so.
I would bet that if you did some load development (gasp!) with perhaps a slower-burning powder and those hotter Rem 9.5 primers, maybe even some seating depth change, you'd find a load that works pretty well.
I'm now in the camp that there aren't velocity nodes perse, but rather pressure profiles that work (or don't) for a given bullet/neck tension/seating depth. Change the pressure profile and you get different results. This explains why you can get great results, as an example, with something like H1000 in a 300 PRC, but change to RL33 charged to attain the same velocity, and results go to crap.
This also helps explain the differences I'm seeing in all the testing I'm doing around effective neck tension (primarily neck lubes) - more to come next Friday, by the way, as I head out again with my 300 PRC to do even more validation (or refutation) that neck lube matters.
There's no doubt that the Rem 9.5's are "hotter" than any other's I've used (maybe even the magnums I've used). And yes, I feel sure I can get some improvement with with load development. It's just that I've never had such poor results from any previous loads that were not "developed", even when I used scales that didn't weigh powder near a accurately as I do now. Since those results, I have tried a couple other powders and charges in some good brass and still, at best, only get SD's in the mid teens and ES's accordingly.
The CCI-450's are working really well in the Alpha brass with the load that works well in the Lapua brass and CCI-400's. Tomorrow, I'm doing a little more testing out of some curiosity to see how the larger flash hole works on a few Peterson brass (same case volumes) with the 450's. Yes, I enlarged the flash holes on the Peterson brass.
As I was curious whether the Rem 7.5's would produce similar results as the 9.5's, I tried some with my favorite load and to my surprise I got a great result. I guess all Remington's can be bad.
See pic below:
As I was curious whether the Rem 7.5's would produce similar results as the 9.5's, I tried some with my favorite load and to my surprise I got a great result. I guess all Remington's can be bad.
See pic below:
View attachment 8411745
Makes sense - you used a more powerful primer, which changed your pressure and delivered the sub-par results you got, then dropped to the 7.5s, which brought you back closer to your original.
It's the consistency (SD's) of the 9.5's that are so bad, even though the seating is very consistent. When I use other LR primers brass (e.g. CCI 200, Federal 210M's), I get the same kind of SD's in the 5's, though with a some increase in velocity, as one might expect.
I think you're missing the point - pressure, burn rate, peak pressure and overall pressure profile will impact your SDs. Those 9.5 primers dramatically changed how pressure was produced in your case and took you into a regime that created an inconsistent condition overall.
I used to shoot a lot of 9½'s and 9½m in 308 and 300winmag and I always had good consistency with them. This was close to ten years ago though. Some of my best sd's came from a standard 9½ and imr 7828 in my winmag but they had soft cups so I moved away from them. I quit using them in 308 for the same reason. I shot a lot in an ar10 at that time and I'd get some pretty good dings on them but never had one go off. Still have quite a few of them.
I’m not opposed to this way of thinking at all. I have always wondered why my load development 90% of the time ends. Up right near book max or dead in the middle of the hodgdon suggested h1000 or h4350
I guess I am missing something???
If a particular brand of primer produce a consistent flame and everything else is also very consistent, why would pressure, burn rate, peak pressure vary? Why would consistent primers, cases, bullets, seating depths, powder, etc. produce a "condition" to be inconsistent?
I've used various primers with the same powder load and with various powder loads and different brass and all the SD's trend to be good or decent, when uniformity of the brass and powder charges. Certainly, I get variations from one make of primer to another in velocities that effect POI. But with all the variations I've played with over the years, I've not come across an "inconsistent condition" when all the components were consistent. . . at least, not until now.
Because at different loads/primers and different pressure curves, different things happen within the case/chamber/barrel. It's not enough to simply be consistent (because you can only be just so consistent). You also have to have the pressure curve within a regime that minimizes the effect of the inconsistencies you can't control.
This is a (rather poor) depiction of a pressure curve (pressure on vertical, time on horizontal) with a given case.
The pressure builds, then dissipates as the bullet starts to move and the powder burns itself out. A really accurate depiction would show a little bump as the bullet hits the lands and slows slightly at that moment.
The key ingredient here is powder burn rate formula - first time I ever saw this was in Jeff Siewert's book:
r=Bp^a
where r is the instantaneous burn rate, B is a coefficient related to the nominal powder speed (burn rate), p is pressure and a is a value derived from closed bomb tests on the powder - something I didn't know was a thing until a few weeks ago. Per an email exchange I had with Mr. Siewert, a tends to be between ".65ish and roughly .83."
What's important to note here is that there is a direct, reciprocal relationship between instantaneous burn rate in the case and the pressure in the case. This means that if you spike burn rate (e.g. due to using a "hotter" primer), then you also spike pressure. This spike in pressure then reciprocates and bumps burn rate up, which bumps pressure again, etc. If you don't relieve that pressure quickly enough, you can get into a runaway condition. This is why small changes in conditions can have oversized ramifications.
So, let's take your change to magnum primers - that will definitely spike burn rate and pressure more quickly and deliver a curve that's a little more like (orange):
It will be higher (more max pressure) and narrower.
If you slow things down (e.g. using a slower-burning powder), it will be more like this (green):
Shorter and wider.
Which curve yields tighter pressure grouping when the bullets hit the lands, as an example? A small difference in time when the bullet hits the lands on the orange curve will yield larger pressure differences at that point than the same differences in time would against the green curve. Ideally, you want major events during ignition (like engaging the lands) to be taking place when differences in time deliver the lowest differences in pressure - on all these curves, that is around the apex. The lower, flatter curve (green) is most forgiving across its entire length.
If you could perfectly load everything identically the same, then in a theoretical sense the pressure curve shape wouldn't matter because you'd be moving along the same curve with every shot. But this is the real world, and you can't. So, when you spike pressure, you give yourself less latitude for error in other aspects of the load - ranging from things you can control, like powder charge, etc., to things you can't, like powder, case, and effective neck tension inconsistency.
Why would consistent primers, cases, bullets, seating depths, powder, etc. produce a "condition" to be inconsistent?
I've used various primers with the same powder load and with various powder loads and different brass and all the SD's trend to be good or decent, when uniformity of the brass and powder charges. Certainly, I get variations from one make of primer to another in velocities that effect POI. But with all the variations I've played with over the years, I've not come across an "inconsistent condition" when all the components were consistent. . . at least, not until now.
I'm in the same boat - most of the time. Most of us play in regimes where we don't have to worry about being on the steeper part of the curves (the steep slopes). We listen to others, or read reloading manuals where others have developed good loads and then we play in relatively close proximity. Making minor changes doesn't put you in a regime where other inconsistencies matter as much. This is where consistency in case prep and loading carries the day, and small changes in charge weight and burn rate (and thus, pressure) don't register as much. Engage the lands during those steeper parts, and they do.
p.s. If you haven't read Jeff Siewert's book, it's a tough read, but a good one.
Let's do another one, yall are pretty much two for two so far. Had to tweak the winmag load a tad but honestly it didn't shoot bad. Just a little warm for my rifle.
338 lapua. Lapua brass, H1000, cci250, berger 250 hybrid otm.
Sako trg42. Gen1.
338 lapua. Lapua brass, H1000, cci250, berger 250 hybrid otm.
Sako trg42. Gen1.
IMO it's not that you can 100% disregard load dev, there is definitely some combo's that will shoot better or worse than others and definitely charge weight can have an impact but it's likely less than people think
Pretty much ya.
I can't even remember what was said in this thread. But I'd consider "people" to be the average shooter who does a big long extravagant load dev
I'm not sure either I guess.
When I first started I would just throw a couple charges and see what shot best and call it good. Then I started watching some videos and then did the whole major load dev thing. Now with a bit more experience I've really streamlined my "load dev"
Do you think the person who does the load development loads Hornadys ammo? Do you figure when he gives a spec for a load he says plus minus 2 grains?This ammo?
Bad Hornady ammo 300PRC, 1/2 MOA to 6 MOA based on lot number.
If anyone has insight it would be appreciated! I'm hoping this is the appropriate forum, reloaders would know more about this than anyone. I bought 1200 rounds of Hornady factory 300PRC 225ELDM with the plan to shoot it over the next couple years and then reload those casings to as long as...www.snipershide.com
Got out the other day with the Garmin. Man that thing is sweet.
The first 2 are from the same rifle, Powder charge was basically just a number I picked.
The next 2 are from 2 different rifles, shooting the exact same load and seating depth, that load came from another guy, it shoots well in every 300 NM I know off.
your 17-shot group is almost twice the SD of mine (5-shot groups don't count). I don't see an argument for load development to be harmful or not helpful when this is the proof that surfaces. I never claimed you couldn't get good SD from picking a load, but you guys made it seem like doing a ladder test is crazy, and yet here I am an SD half of yours.
I do not use a mandrel, anneal, or any other weird stuff to claim the process is better.
You posted one SD of like 9 and the other of 4, so which is it?
I could possibly improve it and actually do have more testing planned, that was just an arbitrary load to shoot a couple and get a medium zero on that rifle.
22 shots at 7.8 and 14 shots at 4.7. Both groups are substantially better than your arbitrary loads - so no, I 'm not very convinced this is a better method.
also lol this took you a month and multiple range trips to conjure up a couple 5 shot tests??? (4/26,5/3 & 5/15 trips) I just post whatever happened last time I went to the range - you really thought you were gonna show up and get me with some cherry-picked groups after a month of shooting...... and this is what you come with!
How would you improve your arbitrary load?
So you don't know if you have a 4.7 or 7.8 SD? There is always variations depending on the sample.
Those may 3rd Chrono readings were actually at a match. April 26 was when I lent it to buddy, and May 15 was yesterday, one range trip.
Those 17 rounds are also a brand new barrel, like those were the first 17 shots down it, likely will settle in a bit.
I am planning to try a couple grains each direction to see if the ES/SD are any better but the load shoots well enough that I have another match in a couple weeks and I'd take that load.
I never said it was a better method, I said you could have likely picked a number in the safe limit and it would shoot just as well.
my head is spinning trying to track all these excuses.
Did you post your friends SD as yours???
Hot damn, you had me at "reciprocal"
Don't make me ask you to compute the pressure integral...that's some dirty talk.
You don't like it that's fine.
The only "excuse" is new barrel and no extra time.
Those 2 slower ones. 2931 and 2921 are from 2 different buddies rifles, just picked a number same load. I never claimed they were mine, I did load the ammo for the one.
Hot damn, you had me at "reciprocal"
I forgot how to compute integrals literally the second I got out of my last calculus course in college - haven't missed the knowledge
@MaurygoId I’ll play.
Load development consisted of “how much powder do I need to put in the case to match my teammate’s dope.”
My load is:
Peterson 6.5 Creedmoor SRP brass
CCI 450
H4350
142gr SMK jumping about 40 thou
A couple of shot strings over the Garmin while checking zero and goofing around:
Load development consisted of “how much powder do I need to put in the case to match my teammate’s dope.”
My load is:
Peterson 6.5 Creedmoor SRP brass
CCI 450
H4350
142gr SMK jumping about 40 thou
A couple of shot strings over the Garmin while checking zero and goofing around:
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IMHO, most times:
load development = Rorschach test
Guys just like to go back and forth to the range burning up all their shit until they think they’re seeing what they wanna see.
load development = Rorschach test
Guys just like to go back and forth to the range burning up all their shit until they think they’re seeing what they wanna see.
A person can make themselves believe anything with small sample sizes.
My ammo shoots a .000" one shot group every time.
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