Minimum Loads

I'm sure someone more knowledgable than I will come along soon but my understanding of minimums is that they are there to prevent a 'squib' lodging a bullet in the barrel, then the potential to try and fire another round not realizing the first didn't leave the muzzle resulting in a kaboom. Obviously there are a wide range of barrel lengths along with variations in all the other tolerances so its going to be 'safe for all'. To my knowledge the min's are *Usually* approximately 10% under the maximums but obviously that can change by a lot depending on the burn rate and pressure curve of a given powder.

There is also a rumor / myth (depending on who you ask determines the level of belief in it) that there is a condition of too little of a fast burning powder in a large case that somehow leads to what is known as a "secondary explosion". Many people think its just a 'cover up' for double charges, which are also very easy to do with fast burning powders in large cases.

Congrats on finding a good load that works for you. Just as some people push the limits of max in search of their results; You have pushed the limits of min to find yours. Is it right for everyone else? Nope (could lead to a squib/stuck bullet in someone's 8-10" barrel, if it meets your needs, rock on!

Don't forget W296/H110 that does not play well with light loads more than a few percent below maximum.

If I may add another potential, 'detonation'. Slow burn rate powder in a large case with a lot of air space, has been known to not progressively burn but explode.

When I was young and dumb (er), I was trying to be frugal (well cheaper than normal). I decided that I didn't need all of the velocity and noise I was getting from my 'book' loading in a .303 British rifle. My answer was to just half my normal loading of IMR 4350. One shot fired and it did not go well. I was 13 at the time and didn't know any better. The weapon survived, I still have it, and had to be taken to a Gunsmith to get the bolt opened. Brass case had flowed.... I learned to respect the listed 'Starting' loads.

No it was not a double charge. The case was normally filled to the shoulder with my correct loading.

An observation on 296/H110. I use this powder in my .300 AAC Blackout and have not had any strange or odd results for light/er loadings, sometimes as much as 12 1/2 % spread from high to low. As my bottom loads are at the breaking point where I don't have full function, I have not gone lower.

With the above in mind, stay within the book limits for safety.

I think the minimum loads are subjective as far as pistol rounds with faster powders. I find myself loading at starting or just below starting quite often. And if you look at several reloading books and sites you will see large differences in starting loads.
For autos its probably about the function of the gun. I loaded some rounds for a friend who had bought an old Colt 1903 or maybe it was a 1905. It shot .38automatic and he couldn't find any. I started below minimum with some 38super brass and then just above minimum and the results were interesting. Both rounds fired fine and were accurate but the below minimum did not eject. Most hung up and stove piped. So we knew why the minimum was where it was.
For a revolver who knows? As long as the bullet is stabalized and leaves the barrel. Part of the fun of reloading!

Hondo 60 said:

OK, max loads I understand.
You don't want to go above SAAMI standards.
Bad things can happen if you do.

But where does the "minimum" come from?

My standard .38 Spl load is below minimum, so I won't post it here.
It goes bang every time.
It chronos at 700 fps in a 2" barrel & 750 in a 4".
It has low recoil, so I feel it's good for my S&W M38 airweight.

But what sets the min?
Is it just some arbitrary number? (which I doubt)
Is it a certain percentage under max?

I guess what I'm saying is, I don't understand why minimum loads are just that, minimum.

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I cant see where a 158 gr bullet going 750 FPS from a 4" barrel is below minimum. Thats what i get with 4.0 Gr of 231. Pretty much a standard load....

JIM

One thing Ive noticed, and more so recently is, minimum loads can vary greatly depending on whose data you use.

My Speer manual seems to be consistently hotter across the board, and my Hornady manual the most conservative. Sierras somewhere in between. With some loads, Ive seen Speers listed minimum load being hotter than Hornadays max.

Kind of makes you wonder sometimes. Whos to say who is right?

Other than the obvious bullet failing to clear the barrel, low pressures can cause problems with the brass sealing. I'm not one to use fast burning powders, so I don't have much experience with handgun cartridges in this respect. But when down loading in bottle neck rifle cartridges, it can result in blow by in the chamber, primers can back out and leak too. I've seen bottle neck cartridges in which the shoulders and even the body collapsed, because pressures were so low that the gases were able to blow back, or rather escape down the neck, shoulder, and body of the case.

The most recent incident I saw were some 7 mag hand loads my son bought at a yard sale, in which the IMR-4350 charges were significantly lighter than minimum published data. They all went bang, but the brass suffered collapsed shoulders and the primers leaks, and got backed out pretty good.

GS

If you are going to go for 'below' minimum loads in pistols, I think the main factor is avoiding jacketed bullets and sticking to lubed lead. Proper hardness ( read 'soft' ) lead will fully seal the bore when harder plated or jacketed bullets won't, avoiding the problems others have noted with gas blow by and leading. Bullets stuck in a revolver barrel due to a light charge are much less likely with a lubed lead bullet due to the much lower bore friction compared to jacketed bullets. A good example is the Hornaday manual warning for their jacketed 158gr. in .38 Special: they are very specific about not going below their recommended loads, which just happen to also to be maximum.

If you are going to go for 'below' minimum loads in pistols, I think the main factor is avoiding jacketed bullets and sticking to lubed lead. Proper hardness ( read 'soft' ) lead will fully seal the bore when harder plated or jacketed bullets won't, avoiding the problems others have noted with gas blow by and leading. Bullets stuck in a revolver barrel due to a light charge are much less likely with a lubed lead bullet due to the much lower bore friction compared to jacketed bullets. A good example is the Hornaday manual warning for their jacketed 158gr. in .38 Special: they are very specific about not going below their recommended loads, which just happen to also to be maximum

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Excellent point! I have moved over to loading and shooting lead almost exclusivly except for 38 super. It does take much more pressure to move a jacketed bullet.
I've shot some real soft 44mag loads with 4.5gr of red dot behind a 240gr lswc and its accurate and soft. A long 240gr JHP may exit the barrel ,but you are taking a unnecessary chance.

AK103K said:

One thing Ive noticed, and more so recently is, minimum loads can vary greatly depending on whose data you use.

My Speer manual seems to be consistently hotter across the board, and my Hornady manual the most conservative. Sierras somewhere in between. With some loads, Ive seen Speers listed minimum load being hotter than Hornadays max.

Kind of makes you wonder sometimes. Whos to say who is right?

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True on Hornady being conservative. I was baffled by how far under the other guys they were with a Herco recipe once.

I actually get baffled pretty often when i compare recipes in all of these manuals. Theyre all over the board.

Don't forget W296/H110 that does not play well with light loads more than a few percent below maximum.

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The only issue with low doses of H110/W296 is inconsistent ignition and the possibility of sticking a bullet...

From Hodgdon's website:

Reduce H110 and Winchester 296 loads 3% and work up from there. H110 and Winchester 296 if reduced too much will cause inconsistent ignition. In some cases it will lodge a bullet in the barrel, causing a hazardous situation (Barrel Obstruction). This may cause severe personal injury or death to users or bystanders. DO NOT REDUCE H110 LOADS BY MORE THAN 3%.

http://data.hodgdon.com/main_menu.asp

That said, this site has done successful testing with low density loadings with H110/W296 (reference .357 180gr and go from there)...

http://www.gmdr.com/lever/lowveldata.htm

People often get confused about information found in load manuals. They take a bit of information given in one instance and apply it universally to all further information rather than understanding context.

I've never seen "minimum" loads listed in a manual except for certain volume sensitive powders, notably H110 and W296 and that is done with a note saying to effect "do not load below start level". This is NOT a universal warning for the majority of powders that are not volume sensitive.

The minimum load for a round is where if you go below you stick the bullet. Generally a bit of common sense should be used. Start loads are set at 10% below max for most powders except as mentioned above. Most powders can be loaded well below the start load but if you are working down you will eventually see poor performance, smokey loads, or carbon staining on the outside of the case from poor chamber seal when pressure gets low. This is where you should use your common sense and begin thinking you are getting too low. The worst that can happen is you stick a bullet but you should be watching for that and then you have to just drive it out of the barrel.

For a higher pressure magnum cartridge, using lower data for the non magnum version in a magnum case is quite safe, for example .38 spl data in a .357 mag case for lower power ammo. Shouldn't take a genius to figure that one out. Some will worry about the slight difference in case volume but if you want, try it. A chrono will tell you how much that small amount of volume difference makes in the load and watch out for sticking a bullet if you are trying for absolute minimum velocity.

In snubby revolvers, can you have the bullet exit the barrel with just the primer and no powder like a .22? If so yes, you can work down if you want 500fps or so.

A lot of reloaders think the the first number given in the load manuals is the minimum charge weight but it's usually the "starting" charge weight. Now days they don't even come by it using a mysterious method. It's as simple as once they determine the Max charge weight they reduce that charge by 10% to find the starting charge weight... (like said above)

(yes, yes, yes, except for W296/H110 which is only 3%)

stressed said:

In snubby revolvers, can you have the bullet exit the barrel with just the primer and no powder like a .22? If so yes, you can work down if you want 500fps or so.

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Not in my experience with 125-grain plated bullets, but others may have seen different results.

But what sets the min?
Is it just some arbitrary number? (which I doubt)

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Don't be too sure about that. Sierra's Max loads are an arbitrary number.

Don

Hondo 60 said:

By the way, this is about 125 gr plated bullets & Tite Group powder.
Berry's says to use low to mid range jacketed data, which Hodgdon says is 4.3 - 4.6 gr

My load (tested over 1,000s of rounds) is lower than that, but within lead parameters.

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You can use lead bullet data and mid-range jacketed bullet load data so your load which is lower than the jacketed data is perfectly fine and in agreement with what Berry's recommends for their bullets.

This is directly from the Berry's site:

We recommend using hard cast load data or start with mid-range jacketed data. Make sure data is below 1250fps unless you are using a Thick-Plated bullet that we list a higher max velocity for like the 9mm 124gr HBRN-TP that can be shot to 1500fps in open class guns like a .38 Super. Keep in mind that since our plated bullet has the same pressure curve as a hard cast bullet, the published cast data will be very close to what you will get with our plated bullets. If you use Jacketed data with our plated bullets you can get from 5% - 8% increase in velocity using that data.

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What further confuses matters with the H110/Win 296 is if you read the Hodgdon 3% warning it is for non tested loads.

Look at some of Hornadys data using H110. The spread tested is a lot more than 3% reduction!

Say a 44 Mag with 240 gr XTP the range is 20.7 up to 24.8

A 357 mag with 158 gr XTP is 12.7 up to 15.6

Around a 20% difference,

So the 3% warning is kind of nebulous.

I got a first hand lesson in minimum loads last week with a 1911. I decided to put together some plinker loads using 164gr LRNFP's over AutoComp. In order to get the little buggers to feed reliably I lengthened the COL a little and used load data for 180gr lead boolits.

Suffice it to say, I think I found out what is BELOW minimum!! All the boolits left through the hole in the front under their own power but I got some good practice on tap & rack. Even though most cycled the gun they also failed to seal the brass causing enough blowback that I could feel it. The part that really irritated me was the fact that it took an hour to clean up the gun from all the soot and unburned powder.

I'm still gonna get these things to work but I'll be dropping the COL to 1.100 and upping the charge a couple of tenths. Hopefully sooner rather than later one of them will fly in a somewhat straight line.