SmallCaliberCentral

i just tried a new load for the revolver, its 24 grains of h110 powder pushing the 240 grain hornady xtp. this is the max load and it shot great same poi as the factory. is this powder going to change when it gets hot, I did test it at 20 degrees.
Sportingly
Cracker

It probably will change a bit, most spherical powders are kinda spooky like that. It might be prudent to keep them out of the direct sunlight if you're planning to shoot them in 90+ degree temps.

+1 to what Glen said. I would suggest dropping back a couple grains and working up in hot weather.

My S&W 629 Classic really likes the Nosler 250 gr PT with 21.0 grs H110.

JD338

with this powder all manuals state not to drop below 23 grains as the min and 24 as the max. I may try some at 23.5 as i like to stay middle of the road for all my loads if they are accurate. by staying middle of the road i feel safe should my powder charge be off a little.
Cracker

cracker wrote:.... by staying middle of the road i feel safe should my powder charge be off a little.
Cracker

I agree with your intent, in theory you are 100% correct. The problem with believing you are safe by being in the middle of the road....there is a multitude of factors, beyond your control, that affect the burn rate & pressure of loaded ammo.

I absolutely, without a doubt, am not even close to being an accomplished reloader, but, EVERY firearm is different, even if they are the same manufacturer, model, consecutive serial numbers, etc....they are different. Firearm is a man and machine made item. There WILL be variance. Some slight, some not so slight.

Believe that 99% of people that reload, skip the most important step in reloading. Start at the minimum recommended load...AND reduce by x% (x varies from reload manual to reload manual).

Trying to read primers for signs of pressure is a farce. If you are flattening or piercing primers, you are MORE than 10% over the max pressure recommended. There are other problems that can produce this phenoma as well - headspace issues, oversized brass, incorrect primers, firing pin protrusion, etc, etc.