confused on starting grains on bullet grains

Boltcarrier

Boltcarrier

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i am starting to learn how to read the load data chart

so i am loading 6.5 x55 swedish

using H4895 powder

on the chart for 85 grain jacketed bullet the start grains is 40.0

and then for 120 grain jacketed bullet the start grains is 34.0

so i am confused, shouldn't the heavier bullet would need heavier start grains, ie the 120 gr bullet should need more powder than the 85 gr bullet

but why is it that the 120 gr bullet needs only 34.0 gr of powder when 85 grain bullet needs 40.0
 
I do not know what "chart" you are referring to? Should be fairly straight forward to understand. Powder does not "push" the bullets - it burns and produces gases which expand, and the gases push the bullet. Your rifle is designed to withstand a certain amount of pressure - same amount of gases pushing on a heavier bullet with create greater pressure. So, to keep your rifle (and fingers and face) in one piece, have to keep pressures below what your rifle can withstand - within the same cartridge, heavier bullets get less powder, or a different kind of powder, so as to keep the pressure within standard.

Instead of a "chart" - get a reloading manual - about the first 1/3 to 1/2 of those books will explain this, and how to reload, and how to evaluate pressure, and so on. People have been safely reloading for firearms for 200 (?) years - and some have been blowing them up for about that same length of time. So, by and large, READ and UNDERSTAND, before DOING. And, advice from the Internet is worth about what you paid for it, my post included...
 
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Potashminer hit the nail on the head.
It's all about pressure and a heavier bullet resists moving down the barrel more than a lighter bullet does so using the same powder amount will result in higher pressure.
It's all in the reloading manuals, they're a great investment for the beginning reloader.
 
To expand on the above, each cartridge is rated for a maximum allowable pressure (MAP). That MAP will be reached at a lower powder charge, when the bullet weight is increased, because it is harder to move that bullet down the barrel (higher weight and greater bearing surface)

Finally, H4895 is a poor powder choice for 6.5X55, except for the very lightest bullets.

The 6.5X55 works best with heavy for caliber bullets (140 gr. and up) because of the long throat and fast twist rate. Slower burn rate powders will work better and allow you to attain higher velocities, without exceeding the MAP. You should look for powders such as N560, IMR4831, IMR 7828, RE22 or RE 25, Norma MRP.
 
Philthy1 said:
It may seem counter intuitive for new reloaders, but yes, heavier bullet = less powder.
Click to expand...

true if you're using the same powder for both bullet weights. But heavier for caliber bullets will perform best with slower burning powders, which will have higher charge weights. An example would be loading 30-06 150gr with RL15 (52gr charge weight), and loading 220gr bullets with RL26 (58gr charge weight)
 
Heavier bullet take more space in the case when loaded SAMI. As stated above, higher pressure - harder to push out.
Slow powder or quantity dot not produce more velocity necessarily.

Stick to manual. Part of selecting a powder after choosing your brand/bullet weight, is to look for the powder that give the fastest velocities.

But since you start reloading, have a look at Sierra Bullet manual ($6/$7. online edition) they indicate the best combination - for accuracy and hunting they found in their lab testing.
This is always have been a good start and good loads to begin with.

Read the first section of your manual about reloading before going into the table...you will have accurate technical explanation to your questions :)
 
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Potashminer said:
I do not know what "chart" you are referring to? Should be fairly straight forward to understand. Powder does not "push" the bullets - it burns and produces gases which expand, and the gases push the bullet. Your rifle is designed to withstand a certain amount of pressure - same amount of gases pushing on a heavier bullet with create greater pressure. So, to keep your rifle (and fingers and face) in one piece, have to keep pressures below what your rifle can withstand - within the same cartridge, heavier bullets get less powder, or a different kind of powder, so as to keep the pressure within standard.

Instead of a "chart" - get a reloading manual - about the first 1/3 to 1/2 of those books will explain this, and how to reload, and how to evaluate pressure, and so on. People have been safely reloading for firearms for 200 (?) years - and some have been blowing them up for about that same length of time. So, by and large, READ and UNDERSTAND, before DOING. And, advice from the Internet is worth about what you paid for it, my post included...
Click to expand...

thank you for a very good explanation. confirmed by the rest of the commentators

i actually am reading the Lee reloading book but i guess i misunderstood about the section on pressure.

i think Lee should have used your explanation at the beginning of the chapter then things would have been easier to understand. He got a bit too scientific with charts and test results that actually really confused me.

interestingly enough, after your explanation, i went back to the chapter and now things started to click.

thanks again.thanks all.
 
If your mind works like mine, I visualize the area under the pressure curve as the powder burns and the bullet moves down the barrel. Heavier bullet, less powder, or slower powder that doesn’t ramp up the curve so fast. Same as t by e difference between a high reving Indy motor and low rpm high tq diesel. The idea is to keep the peak pressure under the max with the biggest area under the graph you can get. Pushing not quite hard enough to break anything, if you are looking for max velocity. Accuracy isn’t necessarily at max velocity though. Depends on your application. That’s why there is a Grand Caravan in my driveway.
 
Interesting parrallel made with an internal combustion engine - my understanding as well. As the bullet leaves the cartridge and moves down the barrel, the expansion chamber is getting bigger, so that the gas volume from a suitable powder is actually not growing in a straight line - you want gas production to increase as the chamber gets bigger, or you stop accelerating the bullet. But, if the bullet is too heavy, or the wrong powder is used, that same amount of gas is going to be created from the burning powder and will "push" - whichever way it can - until something lets go - in theory it should be the friction of the bullet against the bore, and its inertia, that "gives" first, but if that is not enough, or fast enough, that gas will find other ways out of the confines!!!
 
Boltcarrier said:
interestingly enough, after your explanation, i went back to the chapter and now things started to click.

thanks again.thanks all.
Click to expand...

And that is another reason to read, then re-read the reloading portion of the manual. Then, get a couple of other manuals and read them. Each will have something to say and when learning how to reload, while they eventually usually get to the same point, the differing paths of the explanations and tips are invaluable.
 
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Boltcarrier

The Swede is an interesting round to load. The bullets tend to be long ( like bullets in the 130 to 150 gr range) and long bullets have a long bearing surface, so can generate pressure quickly if the barrel is a bit tight, etc.

So, with the Swede, I think it is particularly important to start at the Start load in the book and work up. don't be surprised if your rifle needs more or less powder than the one they used in the book.

If this is your first load with the rifle, I suggest loading 5 each, starting at the START load and then up to the MAX, in o.5 gr increments.

Shoot these off the bench, looking to find an accurate load in your rifle, and watch for pressure. Any extra resistance in lifting the bolt means you are into proof pressure range. Way over the Max.

When you do a test like this, be prepared to bring some hot ammo home and pull the bullets.

The Swede works best with a slow powder. I suggest 4350, 4831 or RL22.
 
Potashminer said:
Interesting parrallel made with an internal combustion engine - my understanding as well. As the bullet leaves the cartridge and moves down the barrel, the expansion chamber is getting bigger, so that the gas volume from a suitable powder is actually not growing in a straight line - you want gas production to increase as the chamber gets bigger, or you stop accelerating the bullet. But, if the bullet is too heavy, or the wrong powder is used, that same amount of gas is going to be created from the burning powder and will "push" - whichever way it can - until something lets go - in theory it should be the friction of the bullet against the bore, and its inertia, that "gives" first, but if that is not enough, or fast enough, that gas will find other ways out of the confines!!!
Click to expand...


Geez, i looked at pressure as the air in the tires, the more air the higher the pressure (thus more powder more pressure). i guess i will have to work my way up to the engine level :>)
 
Ganderite said:
Boltcarrier

The Swede is an interesting round to load. The bullets tend to be long ( like bullets in the 130 to 150 gr range) and long bullets have a long bearing surface, so can generate pressure quickly if the barrel is a bit tight, etc.

So, with the Swede, I think it is particularly important to start at the Start load in the book and work up. don't be surprised if your rifle needs more or less powder than the one they used in the book.

If this is your first load with the rifle, I suggest loading 5 each, starting at the START load and then up to the MAX, in o.5 gr increments.

Shoot these off the bench, looking to find an accurate load in your rifle, and watch for pressure. Any extra resistance in lifting the bolt means you are into proof pressure range. Way over the Max.

When you do a test like this, be prepared to bring some hot ammo home and pull the bullets.

The Swede works best with a slow powder. I suggest 4350, 4831 or RL22.
Click to expand...



Being ignorant, i bought a bunch of 6.5x55 bullets with 85 gr and 120 gr jacketed with lead tip.

Sierra pro and match

and some speer spitzer

thinking that smaller gr = smaller powder loads to start - which now i know to be not true

i like your explanation on the long body in relations to the bearing surface and pressure.

guns are getting so darn interesting.
 
rick357 said:
And that is another reason to read, then re-read the reloading portion of the manual. Then, get a couple of other manuals and read them. Each will have something to say and when learning how to reload, while they eventually usually get to the same point, the differing paths of the explanations and tips are invaluable.
Click to expand...

A real fine gentleman, a CGN member, calibrecarstairs, is kind enough to give me a bunch of readings on reloading.

i agree with you 100% that different paths will lead to the same point, i always thought pressure was tires when it should be internal combustion engines.
 
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