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Discussion Starter #1
OK, here goes. I am working up loads for an M700 I had Shaw re-barrel to 6.5-06 AI. When fed the right stuff it shoots better than I do. I have narrowed it down to two combinations that work especially well. Using the 147gr Hornady ELDM ahead of 56.5gr H1000 and 55.5gr H4831 which are both about max without causing loosening primer pockets, I am getting 2875 and 2850 fps respectively out of a 24" barrel. The problem is most reference books, including Hodgdon's, show there should be a four or five grain difference between max loads for the two powders and not the one grain difference I am seeing. Obviously the problem is either an unusually hot burning lot of H1000 or an unusually mild burning lot of H4831. By extrapolating from several sources, the H1000 is giving just about what would be expected for its charge weight but the H4831 seems to require much more powder than expected to get its measured velocity. Have any of you experienced the same thing? I know all powders vary from lot to lot. The Alliant powders were especially notorious for that.

Because I was trying several different powders, unfortunately I only bought one pound canisters. I'm in the process of settling on one or the other and will go to a 8lb canister and start working up all over again. Thoughts?
 

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1) Using the 147gr Hornady ELDM ahead of 56.5gr H1000 and 55.5gr H4831 which are both about max without causing loosening primer pockets, I am getting 2875 and 2850 fps respectively out of a 24" barrel.
2) The problem is most reference books, including Hodgdon's, show there should be a four or five grain difference between max loads for the two powders and not the one grain difference I am seeing.
3) Obviously the problem is either an unusually hot burning lot of H1000 or an unusually mild burning lot of H4831. By extrapolating from several sources, the H1000 is giving just about what would be expected for its charge weight but the H4831 seems to require much more powder than expected to get its measured velocity. Have any of you experienced the same thing? I know all powders vary from lot to lot. The Alliant powders were especially notorious for that.

Because I was trying several different powders, unfortunately I only bought one pound canisters. I'm in the process of settling on one or the other and will go to a 8lb canister and start working up all over again. Thoughts?

https://www.shootersforum.com/handloading-procedures-practices/52931-read-before-posting-forum.html
https://www.shootersforum.com/handl...82161-realities-about-pressure-beginners.html

If you are relying upon your brass as some magical oracle of accuracy in pressure, you'll be lost at sea for a long time. Neither of your "references" list AI data, nor date tested, nor lot numbers tested, nor nominal lot BR variance, or BD variance. So I can only assume you looked at the 6.5-06 data, put in a different case(AI) and decided it was close enough. You are loading in a different rifle, with a different case than they did. Shouldn't be a surprise that the results are different then. You can't look at min and max charges and velocities and simply scale things up linearly; she don't work that way. Burning rates shift with case volumes and case fill, that's why burning rate charts are ALWAYS cautioned as a relative reference only.

Alliant is a marketing brand name, they don't make rifle powder. Who they bought powders from and who they buy powders from aren't the same. So what you think they may be "Well known for" is a bit off base. Whether or not something is Rambo-Extremo or not, has always been application specific and not a universal property.

If you honestly want to know what pressures you are running, buy a Pressure Trace system. It will only cost you about what that rifle costs at the Evil Empire. Then you can see for your self what your burning curves are or aren't doing, what pressures you are or aren't running.
 
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Welcome to the Shooters Forum, glad to have you with us.

This is a fairly common subject that comes up in reloading, and one that certainly deserves the time to properly address. If you've been reloading for a while, you've probably heard all of this before, but here's goes anyway.

When performing load developments pay close attention to common pressure indicators. Although published data is safe to use as a guide, we must know how to discern and read pressure signs, one of which is chronograph velocities, but certainly not limited to just velocities alone. Not all barrels produce the same velocities at the same charges. I have seen examples of this with many rifles, in which two identical models will produce very different velocities.

Bolt lift - Feel for more than usual or obvious significant resistance when lifting the bolt, this right here is very important. Problem with bolt life though, is that when you start to feel obvious resistance you're already into the red zone.

Primer flow or flattening - This can be iffy depending on how well you know your primer brands, but chances are if the primers are flowing out to or nearly completely out to the edge of the pocket, you're likely into some excessive pressures. Top hat appearance of decapped primers is usually an indication of excessive pressures also. However, some primer cups are softer and will exhibit flattening with normal pressures, know your primers.
As far as cratering, cratering can be unrelated to excessive pressure, if factory ammo doesn't exhibit cratering, but your reloads do, than you're more than likely experiencing some higher than acceptable pressures.

Bolt face transfer impressions - Ejector button transfer impressions can usually be interpreted as excessive pressures. However, I've found that some brass is really soft and will flow around the ejector button channel even with conservative loads. I see this often with RP brass. And an out of spec ejector button can produce transfer impressions, but if you see these impressions with factory ammo then you might need to have the button re-fitted.

Primer pocket stretching - If you're using once fired or new brass and the pockets get loose within the first couple loads you're likely running some higher than acceptable pressure loads. But there are circumstances in which this can be related to the brass, something I've experienced with new FC brass on factory ammo.

If you can input enough detailed information and know someone who has Quickload, that might shed some light on this for you. I'm not familiar with the cartridge you're loading, so I can't really help beyond offering the above recommendations.

In retrospect, velocities are not the only, nor are they the most reliable means of discerning pressures. When developing loads, one must apply all the pressure indicators available in order to draw a conclusion, powder lots, temps, and individual firearms can produce very conflicting velocity and pressure results. The chamber and barrel you have may be tighter than a typical production grade barrel, this right here can have a noticeable impact on achieved pressures and velocities.

HBC
 

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Want to welcome you to the shooters forum.

Depending on the brass to indicate pressure is dicey at best and downright dangerous at the worst. Before conventionally accepted pressure signs show, a person can be way over pressure. Going the other way, soft brass will display the same signs at a much lower pressure, leading a person to believe you've reached the end of the string.
 

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Welcome to the Shooters Forum, glad to have you with us.

This is a fairly common subject that comes up in reloading, and one that certainly deserves the time to properly address. If you've been reloading for a while, you've probably heard all of this before, but here's goes anyway.

When performing load developments pay close attention to common pressure indicators. Although published data is safe to use as a guide, we must know how to discern and read pressure signs, one of which is chronograph velocities, but certainly not limited to just velocities alone. Not all barrels produce the same velocities at the same charges. I have seen examples of this with many rifles, in which two identical models will produce very different velocities.

Bolt lift - Feel for more than usual or obvious significant resistance when lifting the bolt, this right here is very important. Problem with bolt life though, is that when you start to feel obvious resistance you're already into the red zone.

Primer flow or flattening - This can be iffy depending on how well you know your primer brands, but chances are if the primers are flowing out to or nearly completely out to the edge of the pocket, you're likely into some excessive pressures. Top hat appearance of decapped primers is usually an indication of excessive pressures also. However, some primer cups are softer and will exhibit flattening with normal pressures, know your primers.
As far as cratering, cratering can be unrelated to excessive pressure, if factory ammo doesn't exhibit cratering, but your reloads do, than you're more than likely experiencing some higher than acceptable pressures.

Bolt face transfer impressions - Ejector button transfer impressions can usually be interpreted as excessive pressures. However, I've found that some brass is really soft and will flow around the ejector button channel even with conservative loads. I see this often with RP brass. And an out of spec ejector button can produce transfer impressions, but if you see these impressions with factory ammo then you might need to have the button re-fitted.

Primer pocket stretching - If you're using once fired or new brass and the pockets get loose within the first couple loads you're likely running some higher than acceptable pressure loads. But there are circumstances in which this can be related to the brass, something I've experienced with new FC brass on factory ammo.

If you can input enough detailed information and know someone who has Quickload, that might shed some light on this for you. I'm not familiar with the cartridge you're loading, so I can't really help beyond offering the above recommendations.

In retrospect, velocities are not the only, nor are they the most reliable means of discerning pressures. When developing loads, one must apply all the pressure indicators available in order to draw a conclusion, powder lots, temps, and individual firearms can produce very conflicting velocity and pressure results. The chamber and barrel you have may be tighter than a typical production grade barrel, this right here can have a noticeable impact on achieved pressures and velocities.

HBC
This is good information. Best is to not use the chrono to work loads. Find accuracy first and then check for fun to see what you get.
Primers are hit and miss as said. Most times a flat primer is a little too much head space from moving the shoulder back but a flat primer with perfect head space is too far with pressures. It is not wise to look for harder primers. A top hat primer is no good, there is a lot of pressure in the flash hole that will throw the firing pin back in the bolt and the primer cup will flow into the hole. Most every shot will give a double hit to the primer anyway. Even revolvers with over power hammer springs can send the hammer near full cock.
Canister powders are held very close to the center of the burn rate per batch. Every batch of powder is never the same but they do a good job getting close for each can we buy. Any burn rate off will be sent to ammo makers that can measure the burn rates and adjust for it. If you worry about lot to lot you are maybe in a danger zone already. There is no sense looking for velocities that your gun can't reach.
I have been in trouble calling a procedure something that I won't say here because it was taken as a personal affront to someone. There is always someone that treads where Angels fear to tread and will say it is OK.
Follow what you are told here and be safe. This might be the only place where everyone will tell you to stop searching for book numbers. Thank and respect them.
 

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I think sometime's we pretty much over think thing's. If I see a load like you saw, as long as it's published, I'll start low and work up. I watch for sticky bolt, extractor mark on the case, extremely flattened primer's, gas leak around the primer's and watch for flame cutting around the pireing pin hole in the bolt, that is really pushing it.. Any of those show up and I back off. But I do run high pressure and usually withing five rounds, shoot my primer pocket's loos. High pressure sign but not dangerous in my opinion. Worst thing that does is shorten case life.

Learn to watch for sign's and which mean something and which don't. I've seen a lot of people think their primer's are flat and they really aren't. They are looking at primer's made with soft cup's. Unless the primer really fills the primer pocket, look for other sign's as well. Get to or three signs, time to stop was probably a grain or so back!
 

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Discussion Starter #7
Ok. Let me clarify. When I refer to Alliant powders I was referring to the Reloader Series R-25, R22, R19, etc. I've used them all and had good luck with them but they did, as I remember, have lot to lot issues and high velocity/temperature variations. I live in Arizona and do most of my load development at temps over 100 and hunt in 40 to 50 degree weather so that's an issue.

You're right, I did not refer to 6.5 AI data. I looked at 6.5X284, 6.5-06, 270 Win and a few others to get an idea of burn rate/pressure in each cartridge for the two powders I had narrowed it down to. They universally showed about a 4 to 5 grain difference between the maximum loads for H1000 and H4831. Much higher than the 1 to 1 1/2 grain difference in my max loads, hence my question.

I have found that many of the pressure indicators I have traditionally used have not been that useful in the AI cartridges I have loaded for. Seems straighter walls of the AI's grab the chamber better and the usual set back causing extractor grove extrusion and hard bolt lift show up later. Well past reasonable max loads. Primer cups are not reliable indicators either since their hardness and thicknesses vary so much. I have been forced to rely on primer pocket expansion as the ultimate indicator. I work up until I get perceptible primer pocket expansion as demonstrated by loosen grip on the new primers when seating, then back off for my max.

I've been reloading for almost 50 years so I've done this before. The only question I had was concerning Lot to Lot variations in H4831. I am a creature of habit and loyal to what worked for me in the past. When it comes to 4831 I always used IMR. It was the claims of low temp variations of the Hodgdon Extreme powders that finally got me to switch. I have been really happy with the groups I am getting but just haven't had that much experience with H4831 to know how far I am going to have to drop my loads when I change lots. If my next lot is more in line with what manuals show, theoretically my max load with this lot could blow primers or even freeze my bolt.

I've experienced a couple of grain difference between lots before but never a potentially 10% difference. Just wanted to know if anyone else had noticed a big variation in H4831.
 

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Hodgdon says they keep the burn rate to ±3% for the Extreme line of powders and ±5% for the IMR line. However, there were complaints in the 90's about different lots of Varget having more variation than that, and I gather that somewhere around 2,000 they beefed up their QC system and that ceased to be an issue. But if your powder is older than that, then it may have more difference than current ones do. You could always contact Hodgdon and ask about your particular lot number and tell them what you're doing.

Edit:

I modeled your round in QuickLOAD by taking the 6.5-06 A-Square and increasing the case water overflow capacity by 1.8 grains, reflecting the difference between .30-06 and .30-06 AI. You can measure yours for concurrence. I used a COL of 3.340". In that configuration, if I use H4831, I get your 2850 fps stated velocity with 54.7 grains, 0.7 grains less than you are using. However, the ±3% burn rate variation takes that velocity from 2804 fps to 2891 fps. So if I up the charge to 55.5 grains, the velocity range goes up to 2844 fps to 2930 fps. Also bracketing your 2850 fps number. So I think your lot, as compared to the one used to develop QuickLOAD's model, is about 2.6% slower, and that is within specifications. For H1000 I had less luck, but not impossible. I show your lot has to be about 7.7% faster. That is outside the 6% window that would be present if QuickLOAD's tested lot was 3% below average and yours was 3% faster. That said, we have left the gun out of the equation. Assuming yours is not at tightly chambered as a SAAMI standard test barrel (these have minimum chambers within half a thousandth of an inch) and that your bore cross-sectional area may not match exactly, giving you a slightly different expansion ratio, then the apparent differences may be accounted for. But either way, you do seem to have lots at the opposite extremes of the tolerance range. Also, it takes some time for a barrel to settle its fouling pattern once you have established one load, so you may see that.

Note that differences in primers and other factors will also affect how these powders compare to the way they did for Hodgdon or other users. If I don't alter the QuickLOAD burn rates at all, then it does take about a 4.5 grain difference in charge weight to get the velocities you are reading. If your chronograph is optical, change in light conditions from firing one load to firing the other may move velocities around a bit. So, an exact comparison becomes difficult. In neither model, incidentally, did peak pressure prediction exceed 59,000 psi.
 
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Discussion Starter #10
Guess I'll have to be a little cautious. It's been my experience that if I work up to similar velocities with the new lot the pressures should be similar as well. Fortunately, I started pretty light with this workup, so if I use the same starting load and get a similar velocity as with this lot, I should be golden. Either way I should get a general idea on what to expect.
 

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It was the claims of low temp variations of the Hodgdon Extreme powders that finally got me to switch. I have been really happy with the groups I am getting but just haven't had that much experience with H4831 to know how far I am going to have to drop my loads when I change lots. If my next lot is more in line with what manuals show, theoretically my max load with this lot could blow primers or even freeze my bolt.
When I finally got my original reply done I was falling asleep at the wheel, so to speak, so If I seemed a bit course it was not my intention.

Those claims by Hodgdon are not universal, they are designed for. As an examply, What we call Varget was designed to be used in the 7.62 NATO with ball ammo. Works very well. In the 223 many people SWEAR by it, and will provide very good groups. But in work done by Denton Bramwell, he showed that relative to H335(1930's patent date) it was quite temp sensitive.
Sensitivity is real, and can be an issue. Just don't be quick to blame a powder universally, is my point. RJ has found RL-17 to be quite sensitive in one of his cavernous monsters, but I have the pressure traces to prove that isn't the case when used in the Creedmoor.
Also, Hodgdon is very famous for silently changing suppliers without any PSA. IMR 4064 is a good example. Roughly a year ago, the 8# jugs were comming from Rhinemetal, where the 1# bottles were still a General Dynamics powder. Hodgdon told us that the "New" copper cleaning revolution was brought to the world by them from tech developed for the US military.
Actually those compounds were discovered and used for that purpose by the French, around 1900. The Powder that spawned CFE223 has been in refinement by General Dynamics for over a decade in the "green ammo" project however.

So, as always, never ignore a sound caution. But when the marketing arm of a surplus re-seller/powder blender that still uses CUP data tells you they have an elixer that will stop your hair from falling out, keep your wife in love with you, and will wash the dishes for you... Take that for what it is, and not what you wish it was. No different than the "Just the tip" line used by a certain company and college kids, and with the same sincerity. :D:D

As far as how much drop, the bottle tells you 10% between lots. I know 3-5% tolerances get tossed around a lot as what Hodgy told someone somewhere. They CAN have lots that close, but THEY aren't as a matter of course; I've pressure traced 14% lot variations.
If they really were that tight, why wouldn't they list that? They would be able to brag that they have better controls than the other company who does list variations. Because they couldn't flop suppliers at the drop of a hat, and would limit what they can blend and sell.
 

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I can understand heat. That can be much more then lot to lot. It is why the 4227's never go in my .44's. I see a change after only one shot and as the gun gets hotter it keeps getting worse with velocity and pressure increase. It is the only powder I do not recommend for the .44 mag.
But even old powders like 4831, 3031 and many others never gave me a problem. I now love Varget for the 6.5 Swede.
I still say it is wrong to look for only velocity to see how high you can go.
 

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Discussion Starter #13
Hey Darkker, I just got back from the mountains and read your post. Very informative. When I think back to workups we did for my son's 280 AI, it helps explain why we got some surprising pressures form loads with IMR 4831 loads that should have been mild based on similar loading I had done with my standard 280 using the same lot. It just didn't act the same as what comparisons with other powders did. Thanks for the info.
 
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