I have not had the experience thus far of having a load go too far (because I usually find the best group under max). I can usually get to the developement in a cooler month, like march-may, but when I go to shoot crop damage permits, it can often be 90 degrees.

First, what are the things that point to over-pressure (other than pushing primers backwards)? How do I find them? measurements?

Also, does anyone know where I might find a list of temperature sensitive powders versus non-sensitive powders?

Thanks

There are several indicators, none of which by themselves necassarily mean high pressure.

The most obvious is a blown primer. Stiff or difficult bolt lift is also a pretty good indicator. Primer condition has some merit but is probably the worst as there are many things affecting them, not the least of which is variances in the cap material in hardness and thickness, as well as firing pin impact.

Measurement of the pressure ring is one indicator widely used and is covered by Waters in his bood of Pet Loads.

ALL propellants are sensitive to heat, even the Hodgdon Extreme line. I've found them not much different than any other when the temperature is above 75� or so. Supposedly the ball powders were formulated for military use to be tolerant of heat but I've personally never found it so.

[ 02-26-2003, 23:42: Message edited by: Bob338 ]

This was linked by someone else previously and I, for one, found it very educational. It's extremely long but you can figure out who to listen to and so forth and then scroll through to other messages. Oehler himself even has a message in this thread towards the end. I encourage you to take the time.

Reed

http://talk.shooters.com/room_48/8525.cfm

Start your load workup from at least 10% below maximum, or at the recommended starting load given in the manual. Work up toward max. in small increments, this depends on the size of the cartridge and speed of the powder you are using. I work up in half-grain increments with cartridges the size of the .30/'06 when using powders like 3031 or slower; I use one-fourth grain increments with cartridges like the .222 Remington. If, before you find your most accurate load, you notice that the bolt seems a little harder to open than it did on the previous shot, you are arriving in excessive pressure territory. Unless you have a very highly polished chamber or a minimum-taper case, this should happen BEFORE you start to stretch primer pockets or, worse, blow primers!! When you get difficult bolt lift, drop your powder charge by several grains and quit experimenting with that powder. You might now want to start your load development over again with a slower powder!!

Also, examine the case head of each fired case after removing it from the gun. If you notice any kind of bright spot made by the bolt face, or ANY marking of the case head made by the bolt face that is not on the previous one, drop your powder charge by several grains and quit, or start your load development over again with a slower powder!! If you get to the point where you have a blown primer, reduce your powder charge from there by AT LEAST 10%, or start your load development over again with a slower powder!!

[ 02-27-2003, 19:07: Message edited by: eldeguello ]

thank you gentlemen.

When you have to pull the bolt out of your forehead . . . back off 1 grain.

Sorry, couldn't resist

JohnTheGreek

yea, or when the barrel splits down the middle.

I thought that was what was meant by "breaking-in" the barrel. You guys mean I overcharged my loads

I suppose I just add 50fps for each inch of my extra barrel length correct?

On pressure signs it might be any of the common things as mentioned above. Any one of them stops me right there. But unless you have a wildcat or something wrong with the gun the maximum loads listed by the powder mfgs or in manuals stops me also.

I have had only one blown primer in 50 years of handloading and that was when I was starting out and the little yellow piece of paper that Hogdon sent with the keg of ball c was wrong. I learned from that and always check at least two sources.

For barrel length effect on velocity use 25 fps/inch.

For velcoity just average two manuals. This is close enough.

FPS per inch. Seen a lot of different things written.
Some claim as little as 25fps, some as much as 200fps. Lots of variables.
Like powder burn rate, caliber, tight/loose bore, twist, bullet type etc. For example, taking two inches off a 24" barrel will not make as much difference as taking two inches off a 20" barrel.
Chronographs can be had cheap,find out the truth yourself.

Re. barrel length -- Charlie Sisk has posted tests with several cartridges on 24hourcampfire.com -- I think he generally figures 20-30 fps.