Where in the powder charge range works best?

T

tpcollins

New member
I've seen on some forums where guys like to use the maximum powder charge allowable and even exceed it just a tad and claim to shoot keyholes with those charges. I've never been that fortunate.

It seems like I get my best groups using 40% - 50% of the specified powder range on the Hodgdon website. Just wondering if others have found the same or is it just me? Thanks.
 
CAUTION!

Well, this is dependent on what you are shooting. In a lot of handguns, cartridges producing low velocities using fast powders are best for target shooting because what you describe is common. In rifles, using rifle powders, what you describe is actually dangerous. Dr. Lloyd Brownell showed decades ago that shooting rifle powders (his were mostly IMR 4198, 3031, 4895, and 4064 in a .30-06 at that time) at 40% case capacity would occasionally produce a measured 2X maximum pressure spike, well over proof load levels. He said the barrel of the gun they used in his tests (a nickel steel Springfield '03) had bulges in several places before they finished testing.

With rifle powders you should generally avoid loading below 70% fill of the space in the case under the bullet (70% load density), and never go below 60% unless the manufacturer states specifically that it is OK to do with a particular powder whose characteristics are unusual in this regard. Having seen Brownell's pressure plots, I won't do it even then and keep 60% as a hard limit.

At 40-50% loads, pressures are going to drop very roughly in proportion to an exponent of around 1.5 to 3, depending on the powder, so you are at 1/3 to 1/16 of normal operating pressure. With typical rifle powders, this is going to produce very dirty burn (lots of residue left behind) because slow powders burn very incompletely at such low pressures, so most of the powder is wasted. Switching to a bulky fast powder like Trail Boss is much better for such slow loads and will use much lighter charges that burn much more completely and cleanly and will save you money in dollars per foot per second at the muzzle.

If you are working with rifle loads, the accuracy you see will be at short ranges and is due simply to the recoil moments and pressures being too low to distort and whip the barrel around. Once you get beyond 200 yards, the large arc in the trajectory will make for a lot of vertical stringing because the low loads will product inconsistent muzzle velocities. Making higher pressure loads shoot accurately, particularly in a rifle with a light weight barrel contour requires tuning the loads to coordinate the moment of the bullet exit from the muzzle with a calm spot in the whipping cycle and in barrel distortion. I and another board member are starting to explore a new approach to this, but for now Dan Newberry's OCW method seems to be the best one around. Once you get a bullet correctly synchronized with the muzzle, you should get good groups and have the velocity consistency and flat shooting that will let you shoot well for hundreds of yards.

Let us know what chambering, barrel length and bullet you are loading, and w can make recommendations for light loads for short range. For long ranges you will find you actually need more velocity.
 
I assume you are trying to say mid-range, not 1/2 max. But yes, off max is usually better. Competitive shooter in my office would confirm. I can confirm with .308 and Benchmark. Stay within book, always IMHO, YMMV.

I have also found that if I limit to mag max COAL, that performs best. Bolt and 1 at a time would require more work. I'm not interested.
 
What types of cartridges are we talking about? low pressure revolver loads, magnum revolver loads, rifle loads, semi-auto handgun loads or something else? Without knowing this any answer is sheer speculation.

As Unclenick noted shooting 50% of max in a rifle load is going to cause problems. And for that matter 50% of anything is probably going to be a problem unless it's a magnum revolver load and then it will probably just be dropping you into "special" territory.

If you're talking about loads right in the middle of the min / max for a given load recipe it is not uncommon to have the best accuracy here. The min and max listed are to keep all the loads in a similar ballpark for pressure without any regard to accuracy.
 
Ah! Jeff may be correct. The OP will have to clarify. I took the percentage literally and not as applied only to the difference between minimum and maximum. If that's the case, then he is safe.

The bottom line will still be the barrel time synchronization. Benchrest competitors are usually the ones reporting max load levels and beyond to be best. They often have very heavy, rigid barrels that don't suffer the same degree of pressure distortion and flex that sporting rifle barrels do. Richard Lee suggested middle range loads always work best for him in less specialized rifles as well. This is just one of those things you have to test in your gun, though. As you might imagine, a loose chamber or an extra long freebore may get you only to middle range pressures even with a maximum load.
 
Jeff may be correct. The OP will have to clarify. I took the percentage literally and not as applied only to the difference between minimum and maximum. If that's the case, then he is safe.
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"It seems like I get my best groups using 40% - 50% of the specified powder range on the Hodgdon website".

I was concerned how that would be received. I'm going to load some 105gr Hornady BTHP with Varget and the powder range is 31.0 - 33.0 grains.

Loading towards the max has never seemed to work well for me, so the 40%-50% I was referring to would be in the 31.8 - 32.0 grain starting point. Thanks.
 
All of my most accurate rifle loads are in the middle to upper 75% of the max charge.

I can see loading near max if you need more velocity for bullet expansion.
 
There seems to be two nodes.

One lower down and one higher up.

I go for lower down as I don't need the better trajectory at 100, its easier on the barrel if you do a lot of target shooting (or all) like I do.

I work with some in the upper so when I do get to the 300 yard range I have a better one suited to that.
 
Standard reloading doctrine for generations has been that max loads usually don't produce the best accuracy. But also that every gun is different and there are combinations where it is possible, but these combinations are not the general rule.

The difference in group size may be small, or may be large, every gun is different. Most are very similar in performance in this aspect, but there are exceptions.

What point in the range of published charge weights works best? The one that shoots the smallest groups from your gun. YOUR gun. The only way to find out is to shoot different loads from YOUR gun. The only way to tell if your gun "runs with the pack" or if its at either end of the bell curve is to shoot it.

There's no other way to know.

And, FWIW, the same gun can be in the middle of the pack with load A, and also be at the extreme end (either end) of the performance curve with load B.

Again, only shooting it with the ammo in question will tell. Everything else is just a guess, and may, or may not be the way your gun & ammo combination works.
 
In handguns, I don't see a big difference in my groups...whether I load at the minimum published or the maximum published.

I tend to go to the mid-range between the Min and Max published by Hodgdon.

I never exceed the published Maximum ...or go below the published Minimum ...its not smart in my view. I most often rely on the powder co's published loading tables...over the bullet company or others.
 
In my auto-loading pistols I work a load from suggested starting load up to the maximum listed load while paying attention to the operation of the gun and the ejected cases. I then work from the starting load down to find a minimum load. NOTE: if a hang fire or squib load is encountered I stop. I check the barrel and gun and mark the next load up in the range as the minimum. The rest of the batch it disassembled and recycled.
 
It Depends...

Interesting question. For my M14s, the best accuracy seems to occur at the lower end of the powder charge range. For the AR308s, they seem to prefer the higher end of the powder charge ranges. I don't know why.:confused:
 
Depends on the gun. My .204 and .308 like hotter loads in the 75% range than my .260 which likes them dead in the middle of the spread. Like someone above said there always seems to be 2 nodes. I choose the lower of the 2 for barrel life if it gives me the velocity to stay supersonic out to the target
 
I'm with RC20!!

I have found that there are usually 2 nodes where accuracy is best/ most consistant.

Most reloading manuals recommend finding a load/powder thhat most completely fills the case, without overpressure..
 
I let my rifles determine where the best or most accurate loads are.
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+1

Unclenick wrote a long and well informed post about issues with low charges. As a general rule, don't go below the recommended levels in reloading manuals because, now days, the guys who are making up that data are looking at the pressure curve and seeing things you won't. Alliant deleted everything they had on Blue Dot and rifle cartridges because they saw small changes in components lead to great changes in the pressure curve. There are a number of characters out there recommending Blue Dot in 223, one of them Seafire, and a number of rifles have blown up. This is one:

Catastrophic Failure of Rifle Due To Double Charge of Blue Dot

https://thefiringline.com/forums/showthread.php?t=341348&highlight=blue+dot+257+weatherby+mag

The owner thinks he double charged a case, what is more likely is that he encountered an incompatible combination of powder and case volume.

Back in the day, frauds such as P.O Ackley published insanely hot loads based on the assumption that if the gun did not blow up immediately, it must be safe. One poster wrote that someone he knew copied a P.O. Ackley load and the large rifle primer brass could have been re primed with a shot gun primer!. What little pressure tested data I have seen of Ackley's loads, is that his cartridges were operating 15,000 psia above SAAMI max. His own data published in Handloader 1 show the "lower" loads for 30-06 AI were operating at 65,000 psia, whereas the standard maximum pressure for the 30-06 was 50,000. Ackleyites were pushing loads at and above proof pressure loads.

Gunpowder does not burn nice and linearly like a candle. The slope of the curve is exponential and pressures change exponentially. It is best practice to have as full a case of powder as possible to ensure consistent pressure curves. Air space is a variable that can cause strange phenomenon. There are lots of well characterized light loads, I don't have a worry about using them, but when you start experimenting on your own, you don't have pressure equipment and you don't really know what is going on inside your barrel.


There are many who monkey with maximum and over maximum loads, some of the F Class shooters I know are really pushing things. If your rifle gets best accuracy with a maximum load, so be it. However, maximum loads are very tricky and if you shoot enough of them, you will have have problems. Some of the problems may require someone to unscrew your barrel to remove the stuck case and bolt. Unless the maximum load removed the barrel all by itself.
 
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The adage that loads below maximum are more accurate was coined back when bullets were a lot less uniform than they are now.
You can get good accuracy about anywhere on the chart, but as said benchrest shooters load heavy because a case filling load is more uniform and Long Range shooters load heavy because they are trying to minimize wind effects.

My top .308 load for F TR is below Hodgdon's maximum for Varget because if I go max, brass life is short. I am still somewhat above factory velocity.

My top .223 load for F TR is kind of an oddity. I bought a 6.5 twist barrel for 90 grain bullets. I could load SMKs to Sierra maximum with no problem, but they were not supersonic at 1000 yards. If I pushed the load above Sierra maximum but below Hodgdon maximum, I had disappearing bullets. They were deforming and breaking up in flight. So I went to JLK and Berger bullets. They all make it all the way to the target at load levels that will destroy Sierras, still supersonic for good accuracy, and I am still not up to Hodgdon maximum.
 
I load for 308, and 6.5 Creed mostly with some 30-06 and 300 WSM. It depends on which source you use, but according to some sources my loads are over max by .5 to as much as 1.5 gr. But according to other sources I'm finding the best accuracy somewhere between .5 to 1 gr below what is listed as max charge.

I use my chronograph as my guide. Most typical factory loads for 308 show a 150 gr bullet at about 2820 fps. Somewhere around that speed is usually where I also find the best accuracy with 150 gr bullets. I use the same guide when loading other bullet weights and cartridges. I see no point in hand loading any round and not being able to match factory speeds, and it is usually not hard to do that and also match or better factory loads accuracy.

In more modern rounds like the 308, 6.5 and 300 WSM I can't beat factory speeds and still get good accuracy. But older factory loaded rounds like 30-06 are generally loaded very conservatively. I have always been able to beat typical factory load speeds in 30-06 by at least 100 fps with great accuracy and a load that is still below listed book max.
 
As 44 AMP stated in post #9, depends. I am currently loading my 200 gr. and 230 gr. 45 acp down to 600 fps. without any loss of accuracy in my revolver, 1911, Glock, and XD. 38 spl. in a 160 gr. bullet loaded down to 750 fps with no loss of accuracy from a S&W and from a Python. All you guys loading them rounds up at maximum and above are causing the powder shortage.:eek:
 
Along the lines of erratic pressure...An old hand loader I used to talk to back home warned me some years ago never to download a rifle cartridge below the minimums listed in the manuals.

The example he used was not technical, but does make the point that Unclenick and others have made, albeit less eloquently.

He stated that, if you load a rifle case too light, rather than burning mostly from back to front, it can ignite across the top igniting much more powder initially than would occur if the case were full or nearly full. Essentially, imagine the case is less than half full, if you turn it on its side, and the flash hole is totally uncovered by powder, you could, in theory, immediately ignite a column of powder the full length of the case.

However, if the case is full with the bullet keeping everything in place, it will not matter how you tip the case because the powder cannot move around much.

Now I am sure someone on here can correct where I am wrong about this, but, I have found the best accuracy in loads that are almost or slightly compressed and I have always attributed that to consistent ignition/burn.
 
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