How do you calculate powder weight to bullet weight?

[Recon Racoon 49]

Is there a formula to calculate powder charge to bullet weight? If there is, what is it?

 

I've tried searching, but all I get is gram to grain conversion, or just information about different powder brands.

 

So, NJGF reloaders: whats your secret?

[Pizza Bob 1,488]

There is no direct correlation of bullet weight to powder weight. There are many, many powders to choose from and dependent on the burn rate the charge weight will change. You use a reloading manual - optimally, several - to arrive at a charge weight. Then you start low and work up to where you want to be. Oversimplification, but it's a start.

 

Adios,

 

Pizza Bob

[Pizza Bob 1,488]

Great minds....

[Recon Racoon 49]

OK, so start at the low end for 150 gr bullet which is 46.8 gr of Accurate 4350 and work the load up from there. Seems simple enough, and I don't plan on getting close to maximum powder charge for my caliber (7.7 Jap) which is 52 gr.

 

I'm going to go with 174 gr bullet, and start at 47 gr of Accurate 4350 and max out at 49-50. For the load data I have, that should be enough for the bullet, and still be safe enough for the rifle.

 

If you guys have any more advice, lay it on me. I'm all ears.

[Vlad G 345]

So ... Accurate's website doesn't seem to list any data for 7.7x58 so where did you get it from?

[Recon Racoon 49]

EDIT: PDF didn't upload.

 

Screen shot of ACCURATE.pdf, page 288.

 

[Vlad G 345]

Good to know, it wasn't on their website. It looks like that powder is not at all ideal for the cartridge. It looks like a compressed load that is still way under pressure and under velocity. On the bright side for a plinking load it is foolproof, hard to mess it up.

[xkon 0]

As it was said, make sure you use several references for any load. With accurate arms, who has changed makers several times over the years, make sure to have the most up to date out there. Right now, accurate arms manual is edition 3.5. I had edition 3.4 and when compared to 3.5, there were many loads that varied significantly, as much as a few grains.

 

Specifically, for the 454 casull, I am using aa no 9. I had referenced modern handloading 2, lymans 49th ed, and accurate 3.4. They all had a starting AND max load which is now under a starting load in accurates 3.5 edition.

[Recon Racoon 49]

Good to know, it wasn't on their website. It looks like that powder is not at all ideal for the cartridge. It looks like a compressed load that is still way under pressure and under velocity. On the bright side for a plinking load it is foolproof, hard to mess it up.

 

Velocity difference between factory Hornady loads, and ACCURATE load data are roughly 300 fps. I'll be looking through a couple different books and comparing. But for the longest time, this was the only information I could find on it.

[zoid 24]

Correct me if I'm wrong but I don't think it's possible to have a direct formula or relation for bullet weight to grains of powder because

the rate at which powder burns differs from powder to powder. Also not all bullets require the same amount of powder (ie lead, vs plated,

vs jacketed). So if two of the numbers are variable in the formula it's almost impossible to have a direct correlation.

[Recon Racoon 49]

Correct me if I'm wrong but I don't think it's possible to have a direct formula or relation for bullet weight to grains of powder because

the rate at which powder burns differs from powder to powder. Also not all bullets require the same amount of powder (ie lead, vs plated,

vs jacketed). So if two of the numbers are variable in the formula it's almost impossible to have a direct correlation.

 

Thats what Nick and Pizza Bob have said already. I had a feeling that something like this wasn't measurable. At least in a formula sense of measuring. Its essentially a process of trial and error, without going over the max load, or going under the minimum so much so as to create a squib.

 

The only PDF I have on load data, ACCURATE is the only one that has 7.7 Jap data in it. I have the ABC's of Reloading on the way from Amazon, and I'm going to get Hornady's Handbook of Cartridge Reloading, 9th Edition.

[Parker 213]

I have a Hornady manual which has 7.7mm Jap data. Since it's old it only lists Hodgdon & IMR powders, nothing from Accurate.

 

47.8 grs. of IMR 4350 is max. for the 174 gr. bullet according to this manual. I know if you nose around on http://forums.handloads.com/ you'll find a recommendation for IMR 4064 powder as a good all-around one to use for the 7.7.

[xkon 0]

OK, so start at the low end for 150 gr bullet which is 46.8 gr of Accurate 4350 and work the load up from there. Seems simple enough, and I don't plan on getting close to maximum powder charge for my caliber (7.7 Jap) which is 52 gr.

 

I'm going to go with 174 gr bullet, and start at 47 gr of Accurate 4350 and max out at 49-50. For the load data I have, that should be enough for the bullet, and still be safe enough for the rifle.

 

If you guys have any more advice, lay it on me. I'm all ears.

 

Just for another source, in modern reloading second edition, it lists for a-xmr-4350:

 

150 grain jacketed, 46.8 starting and 52.0c load max. 3.175 oal

180 grain jacketed, 46.8 starting and 52.0c load max. 3.150 oal

 

Same charge for both, different oal.

[Socom 19]

I think he's speaking in terms as in some people or company's fill by volume not measurements.

[Parker 213]

You can Google "Powley's Internal Ballistics Formula," but you'll need a slide rule and a propellor beanie to comprehend it. (Only kidding.) This was done for IMR powders. However, math scholars will delight in looking at this. Some variables remain constant, some change, however temperatures are not taken into account. And as loads get "warm," outside temperature comes into play and may give signs of pressure not seen at colder termperatures. Warm loads that shoot fine at 15 degrees may not do so well in 90 degrees.

 

http://www.mindsprin...ber1/powley.htm

 

or

 

http://www.scribd.co...256/Powley-Math

[Pizza Bob 1,488]

. And as loads get "warm," outside temperature comes into play and may give signs of pressure not seen at colder termperatures. Warm loads that shoot fine at 15 degrees may not do so well in 90 degrees.

 

There are some powders that have an inverse reaction to ambient temperature also.

 

Always use the most up to date load data. Old loading manuals may be way off. Speer #8 manual was still using visual pressure signs (sticky extraction, flattened/cratered primers). In Speer #9 they started to use a pressure transducer and some of the loads changed drastically. Latest manuals are most likely (and I don't know this for certain) arrived at strictly by instrumentation, not observation.

 

Adios,

 

Pizza Bob

[Parker 213]

There are some powders that have an inverse reaction to ambient temperature also.

 

Always use the most up to date load data. Old loading manuals may be way off. Speer #8 manual was still using visual pressure signs (sticky extraction, flattened/cratered primers). In Speer #9 they started to use a pressure transducer and some of the loads changed drastically. Latest manuals are most likely (and I don't know this for certain) arrived at strictly by instrumentation, not observation.

 

Adios,

 

Pizza Bob

 

I agree. I've found that a lot of old load manuals are somewhat more gracious when it comes to powder charges than newer manuals today, which seem less forgiving. I was one of those guys who read a lot by O'Connor, Keith, Askins, Milek, Jamison, Davis, and Hagel and would always try loads they would list in their articles and/or books. Some of Hagel's loads were off the chart but worked extremely well for me in many cartridges. (His 7mm Rem. Mag. loads will never be found in any load manual.) Powder brands and types were limited in selection forty years ago when compared to today's dizzying array.

 

Not related to the original post, but I've found the most inconsistences with slow-burning shotshell powders in colder weather (minus temps up to freezing.) Not so much the powder's fault, but more attention needs to be paid when reloading with the right components. I know not to use straight wall hulls like Federal's (although they are confirmed in load data manuals) and I stick with tapered hulls like R-P or AA's for my hunting loads in 20 ga.

 

http://www.ballistic...tcoldpowder.htm

 

I have not experienced any issues with metallic cartridges but I'm pretty fastidious when it comes to those.

[Recon Racoon 49]

That formula you posted, is WAY to over my head. I would need to study that thing for a while to truly understand it. But thanks for posting it. I registered on handloaders forum, and I'll be asking a couple questions over there once I get my books in.

 

Doing some basic math, I figure OAL using 174 gr projectiles is 3.155 inches using XMR-4350, thanks to xkon for posting those figures. If I use BT bullets, do I need to do corrections to this figure on OAL?

[Greydaddy 2]

reloadersnest.com is a good site too!

[xkon 0]

Do the projectiles you are using happen to have a cannelure on them?

[Parker 213]

That formula you posted, is WAY to over my head. I would need to study that thing for a while to truly understand it. But thanks for posting it. I registered on handloaders forum, and I'll be asking a couple questions over there once I get my books in.

 

Doing some basic math, I figure OAL using 174 gr projectiles is 3.155 inches using XMR-4350, thanks to xkon for posting those figures. If I use BT bullets, do I need to do corrections to this figure on OAL?

 

OAL will be controlled by a number of variables: how close you want the bullet seated to the lands, the length of your magazine box, whether you are crimping the bullet in its cannelure, and how much powder you put in the case. This is a pretty inclusive read to guide you to what you are looking for. You'll find the same info in your reloading manuals when they arrive.

http://blog.sinclair...-seating-depth/

 

Some more forum sites for rifle shooting and/or reloading dope and how-to's:

http://forum.accurat...r.com/index.php

http://www.longrange...com/forums/f28/

http://blog.sinclairintl.com/

[Recon Racoon 49]

Do the projectiles you are using happen to have a cannelure on them?

 

I think so.

 

http://polygunbag.com/7.62x54RTracerTipsLargerView.html

 

I plan on using them, or these:

 

http://www.midwayusa.com/product/165542/hornady-bullets-303-caliber-and-77mm-japanese-3105-diameter-174-grain-full-metal-jacket-boat-tail-box-of-100

[xkon 0]

I think so.

 

http://polygunbag.com/7.62x54RTracerTipsLargerView.html

 

I plan on using them, or these:

 

http://www.midwayusa...tail-box-of-100

 

If it has a cannelure I would crimp it there and see what the oal would be. Most likely it will be in spec with the given overall lengths given

[Recon Racoon 49]

If it has a cannelure I would crimp it there and see what the oal would be. Most likely it will be in spec with the given overall lengths given

 

Gotcha. Just got my brass and Hornady 9th edition manual in the mail today, now I'm just waiting on the press.