Minimum loads and lower safety question

S

Scottish Highlander

New member
I have a question regarding minimum loads or less and are they safe. ???
I'll list in examples to try and explain. Lets say in the book it says minimum load 40 grains which will produce say 2700 ft/sec velocity and you have a max load that is 44 grains and produces 3100 ft/sec.
What I was wondering is if you kept dropping the powder weight in grains below minimum load which is 40 grains what would the pressure do ? Eg: 39 grains = 2600 ft/sec with no pressure signs......38 grains = 2500 ft/sec with no pressure signs........37 grains = 2400 ft/sec with no pressure signs and so on so forth down in powder weight.

What would happen in this scenario ?? I have seen a question else where on the internet and was curios to ask in here since there is so many pro's.
Would the pressure be ok in the rifle but the velocity just fall or would it be dangerous ? My assumption is it would be dangerous....

Any ideas guys ?

Thanks for reading
 
SH,

I had a minimum book reload in one of my 8x57s not expand the case enough to seal the chamber. Felt some gas hit my face. Was glad I had safety glasses on. Since, I've started at 1 -1.5 grains above book minimums for all my rifle reloading.
 
Let's look at a more serious aspect of your question. Which powder for what cartridge. If you're using a powder like one of the 4895's, you can drop down to about 60 percent of the max load without a problem. However, if you're shooting a cartridge using a slow burning powder you're taking a might big gamble that nothing will go wrong. I'm talking the 4350s and slower. With those powders, I don't even go with the starting load but usually a grain and a half above the starting load depending on the cartridge. Using a lighter than the starting load can cause serious high pressure reaction known as Deflagration to Detonation Transition, Pressure Excursion Phenomenon or simply KABOOM. The bad news is you could get away with it for months or even years and then it rears up to bite you in the butt. :eek: Two cartridges notorious for DDT are the .243 Win. and 7MM Rem. Mag. from what I understand but probably no cartridge is exempt AFAIK.
It would help to know which powder and cartridge you're working with.
Paul B.
 
Please read Paul's response at least three times. Never under load slow powders. You would think that less powder means less pressure. Not always so. Some times the pressure suddenly goes through the roof. You never know when it is going to happen, but when it does the results can be disastrous.
 
The people who wrote the book did the experimentation to determine what was safe, and then printed it so you wouldn't have to
 
Thank you for the replys, It was a hypothetical question and some guy was trying to tell me the books are rubbish and you can ignore the load data. Also he said less powder is unlikely to cause high pressure......his words were "only a dumbass would think that " .....seems he's the dumbass :eek:

thanks From Scotaland
 
If you are going under, always try to use the fastest powder you can, or use a powder with known reduced load properties like H4895.

Bulky powders are better, more than 60% case fill is desirable because then there is a higher chance the flash hole will have powder immediately in front of it for positive ignition. Powder position sensitivity often shows up in straight walled pistol cartridges with low load densities (also the reason some shooters get better accuracy when they tip the barrel up and then bring the barrel down before touching off the next round.)

Jimro
 
Thanks Jimbro, the guy claims that you can go below minimum by up to 5 grains on some powders or more. I think I will always stick to load data in black and white!! I also prefer to have as muck of the case volume taken up as possible with powder to make for better ignition. Funny as its the H4895 I'm using just now in my 308 and its a really nice powder to use....
 
Minimum loads, below listed starting loads in rifle cases are not considered safe...you should do as the cast lead rifle bullet shooters do, and use faster powders. Small amounts of slow rifle powders do not produce satisfactory results. Do not go below the suggested starting loads or find listings for light loads using faster powders.
 
Thanks for asking our advice.

Put a small pile of powder on a flat rock and light it. It will flare up and burn. Confine it in a case and it will burn faster. Why? Smokeless powder is formed chemically and physically to burn with predictable, consistent characteristics within certain pressure limits. Let the pressure go above or below those limits and the results are no longer consistent. With often unpredictable results.

Here's a scenario:

A load of powder that does not generate enough pressure to reach its proper performance envelope, but does start the bullet down the barrel. (Sometimes primer alone is sufficient to do this.) And then, because the pressure is not high enough, the bullet stops before exiting the barrel. As the powder continues to burn, pressure rises. But you have an obstructed barrel. In the next few microseconds, you can get waves of pressure echoing between the breech and the bullet's base that can bulge barrels or even rupture things.

Even ballistic scientists disagree on the mechanism of S.E.E. (secondary explosive effect) and even whether or not it exists and what happens when you light up a slow powder at reduced loads, but if you read Hogdon's web site which warns against loading H110 at anything below 97% of max, you get the impression that there is some degree of risk involved.

See also discussions of "quickness" in powders.

Good luck. Be safe. Always, all ways.

Lost Sheep
 
Easier example IMO would be the 38 Spl for the revolver, Speer man. no. 13. Much of the handloads for the 38 have only a single charge listed, not a range, marked DNR (DO NOT REDUCE). It's a balance of what the gun can take and getting a stuck bullet.
 
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Thanks Jimbro, the guy claims that you can go below minimum by up to 5 grains on some powders or more. I think I will always stick to load data in black and white!! I also prefer to have as muck of the case volume taken up as possible with powder to make for better ignition. Funny as its the H4895 I'm using just now in my 308 and its a really nice powder to use....
Click to expand...

I would ignore anyone who says you can go 5 or more grains below published data, because that isn't safe. The good news is that when you are reloading the 308 Win you can load a 175 gr bullet anywhere from 1000 fps to 2650 fps and everything in between.

H4895 has produced some very good reduced recoil loads for big game rifles.

Generally H4895 is used for reduced recoil loads with light for caliber bullets: https://www.hodgdon.com/PDF/H4895 Reduced Rifle Loads.pdf

But if you want reduced velocity loads for heavy for caliber bullets then
a good option is to use "The Load, 13gr of Red Dot."

http://members.shaw.ca/cronhelm/TheLoad.html

If you are looking to make accurate subsonic ammunition for 308 Win using jacketed bullets, Trail Boss is where I would go.

http://www.imrpowder.com/PDF/Trail-Boss-data.pdf

If you cast your own bullets, it doesn't get much cheaper than "The Load" for shooting. If you want a subsonic 308 Win load with good accuracy, Trail Boss is where I would start. Some guys are getting acceptable accuracy with the 175 SMK and Trail Boss when they need to turn their 308 Win into a short range subsonic shooter.
 
I have experimented with reduced loads.
My guess is that in general more guns get blown up from stuck bullets than overloads.
Unlike specific me, I have lost track of how many guns I have blown up with overloads, but none of mine blew up with stuck bullets.

In lots of guns I have worked down until the bullet stuck [I do not shoot again until the bore is clear] or I was down to just the primer was pushing the bullet out the bore. Usually only a soft lead ball with soft plastic wad do well with just a primer, unless the chamber and bullet are designed to get a seal.

In a lot of load work downs, I am trying to get the BB gun sound level out of a high powered rifle. That threshold is usually between 1/2 and 4 gr of Bullseye or Red Dot. I came up with a wildcat, the 50CB, specifically to run below this threshold of one atmosphere above ambient gas escapement pressure. That is the threshold of supersonic gas.

The only notable problems I have had with reduced loads were:
1) 45 Colt H110 250 gr XTP. The primer would go off, but not the powder. The bullet would get stuck in the forcing cone. The two driving variables were powder charge AND roll crimp.
2) 260 Remington with 308 Lapua Palma brass necked down and neck turned. The CCI 450 small magnum primers could not set off more than ~ 40 gr or H4350. This is the opposite of the 45 Colt where too little powder caused a misfire.

To get stuck jacketed bullets out, I like to put oil in the bore and pound on a piston. Don't get air between the piston [hydraulic talk for cleaning rod] and the bullet. This technique avoids the bullet getting wedged in the bore. With cast bullets this is not needed. Just keep pounding as it is like slugging the bore.
 
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This is why many reloading data sources list reduced loads with certain powders for which it is safe to do so. If you want reduced loads, use the ones somebody else has developed at the expense of THEIR equipment.
 
Clark-
I have lost track of how many guns I have blown up with overloads
Click to expand...

I really appreciate having the voice of experience in these discussions so maybe reconsider what you're doing so we have it for a longer period of time.

Considering the experience you have (and I'm not joking) if you have pictures have you ever considered putting your experience in a book or maybe a series of articles?
 
Dale A, thanks for the attention.

In 1987 I had a paper on power conversion approved for publication, and my employer's CEO [Rocket Research / Olin Aerospace] said they owned me and that would be giving way company secrets. I said it was just math I made up. He told me that they owned anything I made up. This was the beginning of me facing the question, "Do you want a career, or do you want to make money?"
In 1994 I started posting on the usenet gun forum and learning about guns.
I think I have found my voice in TFL.
 
+1 What Dale said.

Clark, you may have saved a number of lives without ever knowing it, by imparting knowledge you obtained by pushing the ragged edge with guns, shooting and reloading.

I know that I rethought the idea of tweaking the 7.62x25 in the Cz-52 pistol, based on your well written if emphatic description of the thin parts of the chamber. Emphatic is good, though. Quiet warnings often go unnoticed.
 
my only comment worthy of mentioning is checking the load data on Steve's Pages. Steve will often show start load data for a particular cartridge/grain bullet/powder much lower than what you'd find elsewhere in some reloading manual or powder company's reloading data Steve's max load data max load will always be higher too.

For example, last week I was curious about his load data for 30-06. I've always used H4895 for reduced loads in this cartridge. Well, I checked his load data on some other extruded powders in the burn rate range of H4895 that Hodgdon shows data for on its website for the 30-06. Steve's start load was lower than what Hodgdon would show...generally it was around 80% of Hodgdon's max load. Hmmmm, Hodgdon shows you can start at 70% of max with H4895 for reduced loads.
 
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