I believe having detailed written steps for everything you do for a load is critical to insure every load is constructed the identical manner every time. This includes new brass prep, fired brass prep, fireforming steps, bullet jump measurements, load steps, scale calibration steps, primer seating, crimping settings, (ad nauseam). With written load documentation.
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Causes of OVERPRESSURE
- Thread starter Coyote Shadow Tracker
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memtb
Well-Known Member
Doing your testing/ load development on a cool day....then shooting on a hot day, or having left the ammo in a vehicle getting hot!
I do all of my load development on hot days, as I could shoot anytime during the 4 seasons! memtb
Web expansion seems to be a common topic lately, clickers, gas blow back, primer craters, and of course good old reliable indicator - pierced primers
Doom2
Well-Known Member
Not to hijack this thread but I have recently come to the conclusion that having written procedures is a real benefit in reloading. When I was reloading for two bolt guns and only necksizing it was simple but throw in two semi autos and full length sizing, throwing charges and using a Chargemaster it gets more difficult to do things consistently. Having notes in a logbook is nice but updating a procedure to include pertinent information keeps it in the process.
esshup
Well-Known Member
In addition to all the above causes are:
1) Not removing case sizing lube from the case
2) A low powder charge will push out a primer. While not overpressure, it sure looks like it!
1) Not removing case sizing lube from the case
2) A low powder charge will push out a primer. While not overpressure, it sure looks like it!
Mike Matteson
Well-Known Member
You missed one. Case length to long, putting the case neck into the bullet area. Which will blow the rifle or brake the bolt.
MagnumManiac
Well-Known Member
Interesting theory.
All the chambers I have measured and the reamers that go along with them have had .030"-.040" EXTRA length beyond MAX case length…so, if you are letting your brass flow that much, then you are doing it wrong anyway.
My brass takes a long time to grow that much, as many firings as 10 to even grow within .010" of that number.
Cheers.
milboltnut
Well-Known Member
You wouldn't be able to chamber a case that's too long.
PddPdd
Well-Known Member
milboltnut,
So if you don't heed the max case/brass length guidance in every reloading book, how do ensure your brass isn't being slightly crimped into your bullet on the closure of the bolt?
Do you use case gauges to measure your chamber and ensure no crimping?
milboltnut
Well-Known Member
I use a case gauge to check case length. I used to try and chamber them before I got the gauge. You use headspace gauges to measure the headspace of your chamber but you already knew that right?
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Solid projectiles especially with long bearing surfaces will run pressure up as well as cases with thicker walls and less volume. As has been mentioned jamming bullets into the lands. Definitely mistaken powder identification, this got me once!
Moisture in the chamber or wet cases.
As an aside, for all of these reasons, I like moderate loads. A 2.5% decrease in velocity negates most of these hazards
As an aside, for all of these reasons, I like moderate loads. A 2.5% decrease in velocity negates most of these hazards
PddPdd
Well-Known Member
I'm talking about "chamber length gauges" sold by Brownells/ Sinclair that are used to measure & determine your max case length as determined by measuring your chamber.
Sounds like you are measuring your brass with a go/ no go gauge, correct?
Ammo that's been loaded for a long time, especially if it is a compressed load. I had loaded some 338WM when I lived in Alaska, then a few (read 30+) years later I got pressure with the first round that I shot, so I decided to pull the bullets and start over. I found two things wrong. First, the bullets were very hard to pull because the dissimilar metals of bullet and brass had actually welded the two together through a process called electrolysis, which is more common in damp environments. The second thing I found was the H4831 was a solid mass that I could barely dig out of the cases with a screwdriver. I ended up destroying everything except the bullets. Afterward, I tried avoiding that problem by seating bullets longer until I needed the ammo, then seated them to proper depth. Now, out of respect for the importance of neck tension and its effect on accuracy, I try to load and use together as much as possible.
