Wrong Powder = Disaster

This article is about loads that are unsafe in ANY rifle.  Please do not use the loads in this article for the basis of reloads.  Check your loading data against a reliable source before attempting to work up a load.

 

I’m not going to use names in this article to protect the guilty.  I was sitting in my recliner reading an article while sipping my favorite single malt Scotch whisky and loving on one of my three vizslas who had won the prize of Dad’s lap for this particular evening when the phone rang.

“Hello.”

“Jay, I need you to run a pressure calculation for me.”

“Okay, let me get to my computer.  Ready.  “Whatcha got?”

“.300 Winchester Magnum, 26” barrel, 168 Gr. Sierra MatchKing, 71.0 Gr. IMR-4198.”

“Okay…wait…what?  You mean IMR-4831.”

“No…IMR-4198.”

“That much IMR-4198 will blow that rifle up!”

“You think?  I’m sending you the pictures now.”

While looking at the pictures sent to me I asked, “Is the guy still alive?” In fact, the person who made this mistake was surprisingly barely injured.  One cannot say the same about the rifle.  Apparently, the reloader accidentally grabbed the wrong container of powder.  I did the calculations that the caller had requested. The sheet is shown at the end of this article and is pretty technical.  But, here is the bottom line.  The average allowable chamber pressure for a .300 Winchester Magnum is 62,366 PSI as established by SAAMI.  For IMR-4198, 71.0 Gr. behind a 168 Gr. Sierra HPBT MatchKing bullet would generate a maximum chamber pressure of 115,943 PSI, almost twice the allowable maximum.  Look at the red line in the graph.  On the other hand, 71.0 Gr. of IMR-4831 behind the same bullet generates only 54,364 PSI, well below the safe upper limit.

Given the paucity of ammunition over the last several years, and the high price of ammunition when one could find it, a great number of people have started reloading their own ammunition.  In fact, reloading one’s own ammunition has a lot to offer in the way of benefits including price savings, increased accuracy, increased velocity, the ability to use different premium bullets, and it’s just plain fun.

I started reloading when I was 12-years-old under the very watchful eyes of my twin uncles, who ensured that no harm came to me or the rifles I had borrowed from them.  Over the next 40 years, I’ve learned a great deal about reloading and how to avoid accidents.  Here is a list of rules or guidelines that can save you a whole bunch of heartache.

It seems like it would not need to be said, but sadly, it does: do not use the internet as the sole source of information for a load.  Anyone, regardless of their experience or credibility can post a load on the internet.  I do use the internet to obtain information on loads, but I subscribe to a reputable service: LoadData.com. This website is published by the same people who publish Handloader, Rifle, and Successful Hunter magazines.  I will also use the websites of powder manufactures for information on loading data.  When I find a load on the internet I always use the common sense test to determine if the load might be safe.  I confirm the load using published data and run the load through QuickLoad^© before even considering dumping powder into a case.


If the velocity seems too good to be true, it is!  The laws of physics dictate muzzle velocity and one may never, ever break the laws of physics.  Think back to your high school physics (you did pay attention, didn't you?) and recall the formula for Newton’s Second Law where,

F = ma

 
F is force (caused by the burning of powder in the case),
m is mass (the weight of the bullet), and
a is acceleration (the change in velocity from resting to the bullet's peak velocity).

a = F/m

If we rearrange the formula (applying some of that Algebra you swore you'd never use!), we see that
To make a bullet go faster, one must either reduce the mass of the bullet or increase the pressure of the reaction in the case to increase force.  There is no other way to make this work. The problem is that all SAAMI-recognized cartridges have an industry peak pressure.  Exceed that pressure at your own risk!

Never have more than one container of powder open and on your loading bench at any one time.  In my 40 years of reloading experience, I have only broken this rule a handful of times, and in those few instances I almost made a catastrophic mistake.  Don't break this rule.

Distractions cause mistakes.  I was loading 6 mm HAGAR rounds for a high powered rifle competition a couple of years ago and had the television above my reloading bench tuned to the Saint's game.  Because I was dumping powder into cases, and because the cases could not physically hold a double load (dumping powder into the same case twice), I felt it was safe watching the game.  What I didn't count on was not dumping powder into five cases.  I was well
on my way to winning the Master Class when I squeezed the trigger on the 600-yard line and heard "CLICK" but no "BOOM!"  Oh, no.  It happened five times that day and I dropped a whopping 50 points from "saved rounds."  In a sport where one must never drop more than 15-20 or so points to win the Master Class, it is impossible to drop 50 points in a single stage.  Doom on Jay…
Another thing that one would assume need not be said is, drinking and loading do not mix.  Really.  Don't do it.

IMR-4895 and H4895 (and many other combinations with the same number) are NOT interchangeable. Consult specific data for the powder you are using.
Do not use relative burn rate charts to select an alternate powder you have in your possession for a load using a powder with a similar burn rate that is not in your possession.  This is tricky business and will quickly get you in trouble unless you have years of experience and a lot of reloading know how.