Overcharges?

M

Mosin-Marauder

New member
An Overcharge doesn't make a rifle unsafe to fire, does it? I was reloading last night and wondered this. If a rifle fired something like 1-5 grains over max, would that be enough to reset the lugs in the action or do any other damage?
 
In short, yes, it could potentially harm the rifle and the shooter. That's why "maximum" charges exist.

If you're lucky with an overcharge, you might just put a ring in your chamber or throat. If you're unlucky, you could be pulling the trigger on a pipe bomb that you've conveniently pressed your cheek against.

The risk of overcharging isn't necessary putting too much pressure on the lugs of the bolt. The pressure of a round going off expands in all directions. If the pressure exceeds the ability of the bullet to get out of the way fast enough, it's got to expand somewhere, likely out of the side of chamber or sides of the barrel.

All that being said, there's going to be someone who comes along and says that most modern rifle over overbuilt for the pressures of the cartridges they were designed for, and that they were careful when developing their load and they've shot thousands of rounds loaded over max through their rifle.

Of course there are exceptions, people have been hot rodding cartridges since cartridges were invented. People have also been blowing up guns since guns were invented.

Unless you have a lot of experience and completely understand what you're doing, I see absolutely no reason to exceed maximum published load data.
 
An Overcharge doesn't make a rifle unsafe to fire, does it?
Click to expand...

Rifle: No, and then there is that 'depends'. In the old days reloaders preferred Winchester cases for rifles because straight across the options the Winchester had the most capacity then there was that thing about Winchester cases weighed less than other cases by other manufacturers.

then there is that thing about barrels that are +/- in diameter. Then there is the reloader. To answer your question a reloader should know the effect pressure has on the case when fired. A case head upsets when fired. How much? normal case head upset is considered to be .00025" with factory loads. A case head that expands .001" with the first firing is the effect of the 'from 1 grain to 5 grains' over the maximum.

We spend a lot of time talking about case life.

F. Guffey
 
Some loads in some guns can be damaged before you reach max. That is why they have a starting load and tell you to "work up" from there. If max load was safe in every gun, there would be no reason for starting loads. Many people get the false idea that starting load to max load is the range that is safe for their gun as opposed to the point of where to start, and where to stop only when no problems are encountered on the way up.
 
"...1-5 grains over max..." One, not likely. Five, more likely.
Like F. Guffey says, then there is that 'depends'. Manuals change over time due to the testing using different powder lots, much better testing equipment, etc. And they vary from one manufacturer to another, but Max is Max.
.00025" is insignificant. That's 1/100,000th of an inch.
 
The thing is, to find the max for your rifle slowly, by working up. Ken Waters discusses this in the book Pet Loads complete volume.

There's ways to do it as well. Like Guffey mentioned, using a case with more case capacity. Then there's loading longer than book OAL (not at lands or into lands.
 
Lets assume the cartridge case does not rupture. Firearms are built to carry a load, but they are not built to indefinitely carry a load, a reasonable number of load cycles would be between 5000 and 10000 rounds. At the end of its service life, you would expect cracks in the locking mechanism due to fatigue failure. A locking mechanism could be built that fired indefinitely, but it would be awfully heavy.

So given the action is to carry a load, and the lifetime is around 5,000 to 10,000 rounds, if the load is increased, the fatigue life is lessened. How much is very unpredictable, about the best answer is sooner.


These are examples of modern mechanisms that cracked, obviously with over pressure loads. If gas has spilled back into the action, because of cartridge rupture, the shooter could have been hurt. All I know is that these pictures were posted on the web, and I assume the shooter walked away unhurt.

Commercial Mauser FN 264 Win Mag






M70 FNSPR 300 WSM






 
One thing to consider about reloads, is that you check your work as you go and check it again, then check it again. Rule No. 1 is, if in doubt, throw it out, just like the stuff in the refrigerator. At least you get to dismantle the round and use the components again in the correct amounts. If someone gives you some handloads, and you were not present when they were made, to verify the loading, accept them if you must, but dismantle them and use the components yourself. Pope Francis could give me a box of his favorite Swiss Guard loads, and I would not fire them, be they blessed or not.

Damage to your rifle is cumulative, like hearing loss. The metal is malleable to a point, then brittleness occurs and it's a given that failure can then occur at any time, even without a hot load. The right combination of receiver temperature and the next pressure event, meaning the next round fired, can cause a failure.

In addition, a lot of rifles are old. As in 75 years old, for a rifle made in 1940. Look for signs of metal aging and fatigue in your surplus rifles, such as surface cracks or crazing. Use a good magnifying glass. Wartime production lines may not have used the best components or processes to make the steel, or properly treated the metals, or have been reliable about rejecting minimally acceptable materials or machining that would not have been tolerated in peacetime.

There are lots of reasons not to use hot loads, certainly a lot more than there are excuses to use them.
 
Depending on the load, powder, rifle bullet, etc., it isn't unusual to see guys load .5-1 gr over published max loads. Occasionally as much as 2-3 gr. But they are working very close to the edge in my opinion. That load might be safe in 1 individual rifle, but not another. It might be safe at 70 degrees, but not at 100 degrees.

As said in some combos it could be dangerous even below a max load. I 've never known of anyone trying 5 gr over max listed loads. I wouldn't advise going over published numbers.

Now at times you'll see numbers in one loading manual that are 2-3 gr different for a max charge compared to another manual. I might use the load showing more powder, but would start low and work up carefully.
 
Yes, an overcharge can certainly make the rifle unsafe to fire, that's a pretty vague statement, I know. But I can share a anecdotal story I witnessed many years ago. During a rifle target shoot, A rifle was loaded with a hand load and fired. Whatever was wrong with the round caused the bolt action to fail and the bolt came out and struck the shooter in the face. It was fortunately not a serious bodily injury, but a smack to the face is not any fun.

I did not personally know the re-loader/shooter so I did not become privy to all the specifics, but the incident did leave a lasting impression on me.

I never go over published numbers, and in some cases I stop well short of published maximums, either because of pressure signs or it's more accurate that way.
 
Most cases- 1 GN- probebly not-5 GN's-probebly yes. Most rifles will handle hot loads to a point. Not one I would want to find out though. Also IMHO- I have never found a load in the max range that has shot as accurate as a Mid Range load, so no reason to go there. It is also hard on brass.
Re-edit- 1 Gn in rifle loads-probebly not-Pistol loads it could be very bad JU JU depending on what powder you are using. Titegroup--1 GN is very badddddd JU JU.:D
 
depends on a lot of things, case volume for one.

5gr over in a 223 will be bad, 5 gr over n a 300 Rum would hardly make a difference.
 
CAUTION: The following post includes loading data beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.

In strong rifles, I work up to brass failure, and back off on the powder charge by a safety margin I design per the variables involved.

I wear safety glasses and hearing protection when target practicing or varmint hunting.
I do not wear safety glasses or hearing protection while big game hunting.

When I am trying to blow up a gun, I do it with a work up, and write down everything that happens. I try to distinguish primary failures from secondary failures. I try to calculate the gun's strength and predict what will fail at what load. Lots of strong guns will not break in a work up, but when the brass fails, gas cutting will damage a lot of the gun. Lots of weak guns just blow up. What separates weak guns from strong guns is the thickness of the steel. It does not matter WHAT kind of steel it is, if it is 5 times thicker, it is stronger.
 
There can't be a generic answer. A caseload of bullseye may blow the receiver to dust an overcharge of other powders could cause metal fatigue and weakening. Your case may rupture, and if the metals of the gun are weak, who knows what will be damaged?

Any quality firearm is able to withstand high pressure and abuse. They all have limits.

I have a book by one of the best designers ever, and he stated that 5000fps was right around the corner. He predicted that over fifty years ago. This tells me that no matter what we do, there are limitations. Projectile weapons in this class may never go much farther than what we have achieved. If we could design powders that accelerated, so that the pressure remained constant, who knows?
 
Its funny but I have found some rifle loads where the case wouldn't even hold published max. :D


Then you have .25 acp where 1 grain over max would be a double charge.
 
TimSr
Then you have .25 acp where 1 grain over max would be a double charge.
Click to expand...

Cartridge brass is C26000 [ 70% copper, 30% zinc] temper H06 [extra hard] that has a tensile yield at 65,300 psi.

But as a cartridge case it is not a simple shape and is not just in tension. To calculate the stress on a case to predict the pressure at which the primer pocket will get loose, the accurate way to do it is with Von Mises calculations.
https://en.wikipedia.org/wiki/Von_Mises_yield_criterion

If we do that for various cartridges and compare it to the registered SAAMI max average pressure, we see we live in some kind of Bizarro world where things may be the opposite of expectations.
https://en.wikipedia.org/wiki/Bizarro_World

The hierarchy I have found through experiment along with a theory freind has calculated with Von Mises calculation:

Starting at the weakest going to the highest strength:
10mm
25acp
7.62x39mm Large Boxer primer pocket
.
Mauser case head with Large Boxer [22-250, 30-06, etc.]
.
Belted magnums
.
222 Win case head [223 rem]
--------------------------------
So strong it does not matter below this line
-----------------------------------
6mmBR [small Boxer]
.
30-30 [despite the nonsense in the Speer load book]
.
.
32 S&W [ strongest case known to man, registered at 15 kpsi]
 
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