Extrapolate powder loads ..

[tommac919]

I was chatting with a bud about loading some 10mm.
He stated he didn't have/find any data for his cast bullets....

I told him, I was taught to go with the next higher weighted ( same type ) bullet he could find and start there as the powder weight would be ok for work ups in a lighter bullet.

He insisted on using a lower weighted bullet and starting there but dropping the gr by the same % of the bullet weight.

I told him, just let me know when u shoot them so I'm not next to u.

Expert info requested ... and why

tia Tom

ps yes will have a Chronograph

[The_Shadow]

What cast bullet and weight does he want to use and what powder does he have to work with?  I have plenty of loading data that may show what he could work with...

BTW, this is exactly why I recommend getting as much data that is available and posted links to old data, to make informed decisions about working with variables.  I especially like data that has pressure values to see if the pressure is already high or would allow for some swapping of bullet type or primer types, etc. 

[sqlbullet]

Since this is a 10mm specific reloading forum, I will state:

I see no issue with using jacketed data for cast bullets of the same weight and general profile.  Special attention should be paid to ensure the to bullets bases are seated to the same depth.  And, as always, starting loads and work up.

The "why"...

Cast bullets are softer, generally have less bearing surface and as a general rule of thumb will develop less pressure than than a jacketed bullet of the same profile with the same load.  There are cartridges where common sense tells you the jacketed data will not work well for cast bullets, but that is generally not the case in the 10mm.  300 win mag is a very different story.

I would also add that the Lyman Cast Bullet Handbook is stupid cheap compared to 1000 commercial cast bullets, and should be on the shelf of anyone who is going to shoot cast bullets.  Not primarily for the load data, but for the wealth of other information which aids in making decisions like the one above.  Richard Lee's Modern Reloading also has a great chapter about lead alloys and pressure.  I am not convinced I completely agree with his conclusions, but reading about his process is a first rate way to learn about developing cast bullet loads, and following his recommendations will facilitate the development of many safe and accurate loads absent specific data.

[475/480]

For many years now I have used the jacketed bullet data for cast bullets, for THE reason sqlbullet states.
In 10MM I have used 180gr JHP data for 190 gr cast loads with very good results.

Sean

[tommac919]

Ok guys, tks... I understand using jacketed for cast...

But above really didn't answer if you work from a lower weight bullet up OR a heavier bullet down like I was taught.... and why too.

[The_Shadow]

I have worked both ways, from lower weights and higher weights, but always started lower and worked upward for the most part.  I have even worked blindly in the beginning, when no data and not much data existed for some powders for the 10mm.  I used Blue Dot because I knew it very well, as I used it with other cartridges.

If you need some data to get him close just provide the what he wants to use, could even scan a page or post a pic from a manual if that would help. 

This is where I posted links to getting all sorts of manuals either in print or pdf format for download.
http://10mm-firearms.com/reloading-10mm-ammo/2014-reloading-guides-available-for-download/

[tommac919]

Tks.. i have that link and copied all... can't have to much data.
And kudos for the work you do.

more ifo to come