Guys, bear with me here. I'm a long time shooter but short time reloader.

What I need help with is interpreting or adjusting a load when the AOL I plan to use is different from what the load guide says.

For example, if for a cartridge the manual lists 45.0 grains of powder X at an OAL of 2.850" but, with all other components being the same, my rifle prefers an OAL of 2.950". If for example I'm switching powders but want to keep the longer OAL how do you adjust the start loads up so you don't waste a ton of time. I've found that by lengthening the OAL the pressures typically go down. Thus the start loads are overly conservative and development takes for ever. Also, how does one estimate what a new reasonable maximum is? This is not an effort to increase capacity in hopes of cramming in more powder. I just find that on some rifles, not all, they shoot better when loaded to a longer OAL.

Thanks.

Any time you change any component you have to re-work the entire load. That includes the OAL.

That goes without saying.

What I'm asking is, is there some method by which you can calculate or otherwise conservatively estimate a new, presumably higher, starting charge?

Poleax,

Steve is right though some further explanation might have helped.

Just because you seat the bullet out further and increase case capacity doesn't necessarily mean you can start at higher loads or even necessarily increase the max load.

Why is because, you don't know how close to the lands the bullet was that was used to work up the data in the load book. So, while you may be gaining capacity with a longer OAL that may be negated by the fact that your bullet could be much closer to the lands. Always best to start low and work up.

I'm thinking you are talking a .308? If so I ran your idea past quickload and if going closer to the lands doesn't make a difference in pressure which I personally don't think it would or it would be minute.....then about 1 grain of powder additional would yeild a very close match in pressure for that extra 1/10 inch case capacity/seating depth.

Even though Quick load and Kracky may be right, why screw with the unknown. You certainly aren't going to get any practical gain. If it is a quest for understanding and knowledge ; start a little lower , work up and learn.

Get the basics down pat before becoming adventurous if you must. If you error it is better to do so by being knowingly cautious than ignorantly bold. Wow! Did I say that?

Kraky,

Yes, its a .308. Thanks for the help. I figured that was about right. I really ought to get that quickload.

I also broke down and called sierra and they pointed out the obvious. In addition to saying exactly what Z1r did, they had some helpful advice about working up loads. I was making sets of 5 with incrementally larger charges. That takes forever and if you hit a point where you suspect pressure it often requires breaking down those that are over. They said just work up one round each in 1 grain increments until your are starting to approach book max then wswitch to 1/2 grain increments. The idea being that you are just looking for pressure indicators. I suppose I had been trying to kill two birds with one stone. Looking for accuracy and also maximum at the same time.

Their suggestion