slow and fast burning powders

s8mdevo

Well-Known Member
Im trying to learn as much as possible before i embark on the world of reloading! Could anybody offer some advice on the difference between slow and fast burning powders and their different applications.
I will be reloading for a .308 with 125gr bullets, and a .243 with 85gr bullets
Are there certain powders that are best suited for these calibers.
I have a few different reloading manuals and own the ABC's of reloading book and they all give many options for various loads but just wanted to know what the difference in the powders are and what applications to use them in.
I hope this makes sense.
 
I don't know the difference between fast and slow powders as it's something I've never even thought about. I've just picked up the Hornday Manual (8th Edition) and opened it on the 85-87 gr bullets for 243 Win page. I see 10 powders listed that will give me a maximum velocity of 3100 fps. I've scanned the list and see I've three of these powders in the cupboard.

I know I can lay my hands on more N160 if I need, so that would be my pick of a powder this evening. As to fast or slow, it's academic to me. It's a technical detail that I'm letting Hornady worry about.

Regards

JCS
 
They're all made of the same basic stuff, nitrocellulose and nitroglycerine. The burn rate is governed by the size and shape of the granules and the retardant coating that is applied. Slower powders have larger granules, normally. Generally the burn rate is matched to the cartridge characteristics, the bigger the cartridge then the slower the powder, plus the smaller the exit hole from the case versus the size of the body of the case, then the slower the powder you need. Taken to extremes, a .22 rimfire needs a fast powder, a .50 BMG case necked down to .22 would need a very slooow powder indeed. I'd recommend the Vihtavuori reloading manual for more details on powder characteristics, but in practical terms you just pick a powder recommended by the loading data and work up loads doing that. You don't necessarily get better loads using powders at one end of the fast-slow range for the cartridge. Sierra do show their best accuracy loads and best hunting loads, which can be useful.
 
They're all made of the same basic stuff, nitrocellulose and nitroglycerine. The burn rate is governed by the size and shape of the granules and the retardant coating that is applied. Slower powders have larger granules, normally. Generally the burn rate is matched to the cartridge characteristics, the bigger the cartridge then the slower the powder, plus the smaller the exit hole from the case versus the size of the body of the case, then the slower the powder you need. Taken to extremes, a .22 rimfire needs a fast powder, a .50 BMG case necked down to .22 would need a very slooow powder indeed. I'd recommend the Vihtavuori reloading manual for more details on powder characteristics, but in practical terms you just pick a powder recommended by the loading data and work up loads doing that. You don't necessarily get better loads using powders at one end of the fast-slow range for the cartridge. Sierra do show their best accuracy loads and best hunting loads, which can be useful.

I have just bought some second hand reloading equipment and included was some viht N140. So basically the best thing to do is to find the N140 load and work up from the minimum? Are there better powders than others or is it all rifle specific and down to personal preference? Thanks for the advice
 
Think of squeezing a water filled plastic bottle with a cork in the top
you can gently but firmly squeeze it and force the cork out or you can squeeze it hard and fast by stamping on it.

The tighter the cork = the heavier the bullet
The faster you squeeze = the faster the powder

Too fast and the pressure gets too high and the bottle pops!!
 
Many of the reloading books have lists showing burn rates of powders.

i'm loving the idea of the .22-50BMG.....May be a tad over-bored and probably only 50 shots per barrel though!
 
If your reloading data or manual lists a load for N140 in the calibre you're using then you might as well try it first, since you have it. Start 10% below maximum (or use a recommended starting load) then work up towards the maximum checking each case as you go for pressure signs. Having done that then you can load batches of 3 or 5 per tested load then see if they group. If you can get access to a chrono then you could check velocities too, but this is more benchrest or F-Class than stalking. Looking through the Sierra manual virtually every powder is a "best" choice for some combination of calibre and bullet weight, so there aren't better or worse powders in general terms. We all have our personal preferences, but powder supplies are so limited from the US these days that we're all having to try substitutes for our favourites. Even the dedicated 308 accuracy shooters seem to disagree on which powder to use, Reloder 15, N140, N540 and Varget are often preferred, but no-one's proved that one is better than another.
 
If your reloading data or manual lists a load for N140 in the calibre you're using then you might as well try it first, since you have it. Start 10% below maximum (or use a recommended starting load) then work up towards the maximum checking each case as you go for pressure signs. Having done that then you can load batches of 3 or 5 per tested load then see if they group. If you can get access to a chrono then you could check velocities too, but this is more benchrest or F-Class than stalking. Looking through the Sierra manual virtually every powder is a "best" choice for some combination of calibre and bullet weight, so there aren't better or worse powders in general terms. We all have our personal preferences, but powder supplies are so limited from the US these days that we're all having to try substitutes for our favourites. Even the dedicated 308 accuracy shooters seem to disagree on which powder to use, Reloder 15, N140, N540 and Varget are often preferred, but no-one's proved that one is better than another.

Thanks, I have done a fair bit of research and a lot of people have suggested N140 for .308 so i guess i will start with this and see my results. It is an absolute minefield for a novice but i think i am hooked before i have even begun!
 
As a general rule, as the bullet weight increases the burning rate of the powder decreases, so light bullets fast powder, heavy bullets slow burning powder.

Ian.
 
s8mdevo,
Perhaps, it is just the phrasing of your question that needs to be changed. However, when you ask for "advice" on the difference between slow and fast burn rates, it makes me believe that you have more homework to do.

If you have read the equivalent of the NRA's Guide to Reloading and reloading manuals such as Speer, Hornady, and Lyman, your questions should have been answered. You ABSOLUTELY must have your theory down before you begin your practice.

I would suggest that you get a few manuals, I use the ones listed above. Read all of the Intro's and basics. They are all the same, fundamentally, but have unique specific differences you may find interesting. Extra manuals are great to cross reference load data to ensure safety.

Next, find a basic recipe. Cross check that recipe with the other manuals. Then starting at the lowest powdered load, try a few.

Ideally, find a forum and someone that is reloading for your make, model, barrel/length-twist, and style (long distance, hunting, precision, ...) and ask them for their favorite bullet/powder/primer combo. Most people are happy to share and their research could save you time and money.

I also suggest that you study all of the manuals and then find someone who has experience to help you with your first batch.

Lastly, don't worry about optimization at this stage. Your main concern is not having catastrophic failure.

Sorry if this comes off harsh or condescending, it was not meant too.
 
Your main concern is not having catastrophic failure.

At the risk of being shot down in flames, I'd like to offer the OP the benefit of my own very limited experience.

I was as confused as he is but after a lot of reading, watching videos and asking questions at my RFD, I made a start without the benefit of a mentor.
I believe that, provided you use common sense and follow everyone's advice to start at the lightest recommended loads, it should not be a frightening business and is very satisfying.

I'm sure catastrophe is a possibility as we are dealing with explosives, but with all the information available in manuals etc and the constant emphasis on safe practices I think you would have to seriously deviate from the recommendations for it to occur.

It's important, while emphasising safety, not to scare newcomers away from a process which is, after all, not rocket science.

Richard
 
s8mdevo,
Perhaps, it is just the phrasing of your question that needs to be changed. However, when you ask for "advice" on the difference between slow and fast burn rates, it makes me believe that you have more homework to do.

If you have read the equivalent of the NRA's Guide to Reloading and reloading manuals such as Speer, Hornady, and Lyman, your questions should have been answered. You ABSOLUTELY must have your theory down before you begin your practice.

I would suggest that you get a few manuals, I use the ones listed above. Read all of the Intro's and basics. They are all the same, fundamentally, but have unique specific differences you may find interesting. Extra manuals are great to cross reference load data to ensure safety.

Next, find a basic recipe. Cross check that recipe with the other manuals. Then starting at the lowest powdered load, try a few.

Ideally, find a forum and someone that is reloading for your make, model, barrel/length-twist, and style (long distance, hunting, precision, ...) and ask them for their favorite bullet/powder/primer combo. Most people are happy to share and their research could save you time and money.

I also suggest that you study all of the manuals and then find someone who has experience to help you with your first batch.

Lastly, don't worry about optimization at this stage. Your main concern is not having catastrophic failure.

Sorry if this comes off harsh or condescending, it was not meant too.

FISMA,

This is exactly the sort of advice i was looking for, its good to be critical i do not want to do anything that could be potentially dangerous and am trying to gather as much advice before i begin. I have a few friends who all reload and i will definitely be getting help from them along the way. I have all the equipment ready to go and am just now finding out what i think will work best in my rifle before my first load of cartridges. I appreciate your advice, thanks.
 
S8

In response to your initial question a quick look at Vihtavuori website shows N140 loadings for a wide range of 308Win bullet weights. - It is a great powder for that cartridge.
For your 243Win with 85 grain bullets (& heavier) their data shows no loads for N140 - You ideally need a slower powder for 85 to 100 grainers. N160 is indicated for that range.
If however you shoot lighter 243 bullets (eg 75 grains) the N140 will do an excellent job & you could safely use it for both 243 and 308.

A good rule to follow as a beginner reloader is to copy the cartridge overall length of commercial (factory) rounds which are loaded with the same style and weight of bullet as you are reloading. - You don't want the bullets too long either for your magazine and especially important the bullets shouldn't touch the lands of the rifling when chambered. (That can give dangerously high pressures) Also you don't want to seat bullets too deep as this reduces the volume inside the case and increases pressure too. Some powder manufacturers' load data includes cartridge over all length & that is a good place to start too - if you cross check data from different sources (eg powder vs bullet makers data) and it matches you will be ok & safe.

Enjoy

Ian
 
Post 15 by Yorric is very sensible.
An advantage of the faster burning powders is their smaller kernel size which makes measuring or metering more accurate.
Viht N140 is ideal for both .243 and .308 cartridges.

HWH.
 
Post 15 by Yorric is very sensible.
An advantage of the faster burning powders is their smaller kernel size which makes measuring or metering more accurate.
Viht N140 is ideal for both .243 and .308 cartridges.

HWH.

Looks like I got lucky on the powder with the kit I bought then, that is good news.
 
S8

In response to your initial question a quick look at Vihtavuori website shows N140 loadings for a wide range of 308Win bullet weights. - It is a great powder for that cartridge.
For your 243Win with 85 grain bullets (& heavier) their data shows no loads for N140 - You ideally need a slower powder for 85 to 100 grainers. N160 is indicated for that range.
If however you shoot lighter 243 bullets (eg 75 grains) the N140 will do an excellent job & you could safely use it for both 243 and 308.

A good rule to follow as a beginner reloader is to copy the cartridge overall length of commercial (factory) rounds which are loaded with the same style and weight of bullet as you are reloading. - You don't want the bullets too long either for your magazine and especially important the bullets shouldn't touch the lands of the rifling when chambered. (That can give dangerously high pressures) Also you don't want to seat bullets too deep as this reduces the volume inside the case and increases pressure too. Some powder manufacturers' load data includes cartridge over all length & that is a good place to start too - if you cross check data from different sources (eg powder vs bullet makers data) and it matches you will be ok & safe.

Enjoy

Ian

Ian, thanks for the tip on measuring factory cartridges I had not thought of that. Great help from all on this forum thanks.
 
N140 is a great powder for 308 and I have a mate who uses it for 87gr in his 243 and gets great results. All the advice above is spot on. I struggled with lighter bullets in the 308 and always came back to the 150gr which is my go to bullet.For the 308 with a 150gr bullet you will find a node point between 43-44gr which is towards the bottom of the ladder keep the COAL at 2.810. There will be a node point higher up if you want to search for it, but the advantage of the 308 is that the bottom point is always deer legal on energy unlike the smaller calibres. Once you get a group that is ok you can alter the OAL which will tighten the group further. My old 308 liked 43.1 gr at COAL 2.825. My present one likes 43.8 at 2.805. This is part of the fun fine tuning the load to your rifle. It will also give you the confidence when you pull the trigger the bullet will go where you want it to.
happy reloading.
BE
 
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