What factors cause too high pressure ?

[meatyrem]

I loaded some 280 rem last week to try a load I shot the week before and it seemed pretty accurate, so I loaded up a few more to check it. First shot I couldn't lift the bolt, had to pull pretty hard and it came open. Ejector mark on case, Ejector jammed with brass. Same load shot fine without any hint of pressure the week before. Got ejector freed up and made sure everything was working correctly. Fired another one and it was fine as were all the rest of them. No flattened primers and no stiff bolt lift.

Maybe that bullet was a little larger diameter than the rest?

143 Hammer Hunters, IMR 4955 powder. Remington 700 Mtn rifle.

I would place my bet on an off powder charge over a larger diameter bullet.

 

[C-130 Dude]

1. Wrong powder / too much powder

2. Too tight neck fit / case crimp

3. Bullet too close to the lands

4. Aggressive leade angle

5. Rifle bore "tight"

6. ???

Are the following things not really causes of overpressure ?

1. Tight twist

2. Barrel length

3. Type of rifling / groove width, number of grooves

4. Below "minimum" powder loads

5. Headspace too tight

6. ???


Trying to educate myself before I begin handloading. As an example, if X grains of powder Y produces
a flattened primer, you could possibly either reduce the powder load, HbN- coat the bullets, or cut a
longer leade.
Please feel free to add to my list !

You probably thought of this, but are there any reloaders nearby that you can watch/get mentored by? Really helpful if you can! Purchase and follow published book loads. Prep and process your brass carefully. There no hard fast rule that produces a perfect load. Others have said it: start low and go slow. Double check your work and compare with the book. If you have a doubt, it's a warning. Take note. Nothing is worth taking a chance. And this list goes on....

 

[bonie]

the answer should be towards the front of any of your loading manuals,