Understanding Pressure

Great Article.

I will echo what Mark204 said in that it was written for the "average folk". The pictures made it very easy to follow and understand.

Thanks orkan!!
 
Temperature increases the RATE of a chemical reaction, which is why loads that work on a 40* day will extrude brass on a 110* day in the sun, not the AMOUNT of energy.

Looking at that Mauser bolt that had the lugs sheared off; unfortunately people aren't very smart these days, lots of stupid going around, and they do not read the loading manuals and load to velocity, they load to what is in the book and wonder why things go wrong.

The only way to truly know what is going on inside your rifle is to use pressure testing equipment such as Pressure Trace and a good chronograph like the Oehler 35p.

Good article.
 
Very helpful article!

BTW the blown-up rifle belonged to Chris Comer (RIP), a shooting buddy, a vet whose father died in WWII on Peleliu, and one of the nicest men you'd ever want to know.

Fulton armory said the barrel was made of a bad batch of steel that was held at too high a temp too long. Consequently, the steel molecules were too big, which eventually caused the blow-up. It was not a high pressure load. That was also shown by looking at the primer of the round in the chamber when it blew up; no pressure signs.

To add insult to Chris's injury, he couldn't replace the rifle as it was grandfathered under one of Kalifornia's goofy AW laws. I'm so glad I left that socialist, leftist hellhole.
 
For a relative reloading newly (only been at it for three years) this was an eye opening article. Made me take a step back and realize how complex accurate reloading can be and how one must never become complacent. Thanks!!
 
Very good read!!! nice to see to step by step surprised that more pressure didn't have the effect that one would think....
 
nice read saved on my computer for future reading. got a 357 mag from my uncle 30 years ago. with some reloads. fired a few rounds then bang pierced a primer. the sound of the shot sounded like it doubled. disposed of the rest of those rounds in a hurry.
 
Very good article!

I’m thinking about getting into reloading and this was an eye opener even about factory ammo! Which after reading it I checked some casings on my once fired .17 Hornet brass. Sure enough, the Hornady 25 grain JHP was hot enough to make the primer look like your early pictures of cratering.

My question about the oil is how do you deal with rifles that get ice all over them, then sweat when brought in? Oil seems unavoidable.
 
Originally Posted By: Flesh Eater
My question about the oil is how do you deal with rifles that get ice all over them, then sweat when brought in? Oil seems unavoidable.

When I get home from hunting in the cold, -15 to -20 at times. I ether leave the gun in the case until it's all at room temp or I take the gun out, dang thing freezes solid, literally, but field strip the gun as much as I can and place the parts over some of my furnace vents and that warms it up and drys it off pretty quick. Plus not having enough lube for it all to be flowing around helps also.
 
Originally Posted By: Rock KnockerOriginally Posted By: Flesh Eater
My question about the oil is how do you deal with rifles that get ice all over them, then sweat when brought in? Oil seems unavoidable.

When I get home from hunting in the cold, -15 to -20 at times. I ether leave the gun in the case until it's all at room temp or I take the gun out, dang thing freezes solid, literally, but field strip the gun as much as I can and place the parts over some of my furnace vents and that warms it up and drys it off pretty quick. Plus not having enough lube for it all to be flowing around helps also.

I've noticed my rifles seemingly dry up within an hour, but they sweat like crazy during the process. I assume if it's sweating on the outside of the barrel, it has to be sweating inside, right?

Do you oil your chamber at all? Would oiling it, then wiping it with a dry rag, or dry swab create the same pressure issues as discussed, or is that usually caused by an excess of oil?
 
Originally Posted By: JMetteVelocity =‘s pressure. That helps a lot if you know roughly where your rifle should be shooting.

To clarify, are you saying velocity is an indicator of pressure?
 
It could be. It’s the closest thing we have to measuring pressure. Nothing is the same in reloading. Everything is different and has variables. But if a safe pressure in a manual states a given FPS with a certain grain. It may take your rifle 1 grain more powder to achieve them same results or it may take your rifle 1/2 grain less. If you’ve got a loose barrel you won’t have pressures therefore you won’t have the velocities. If you’ve got a tight barrel you’ll have increased pressure and therefore you’ll get an increase in velocity with a lower powder charge

Hope makes sense.
 
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