The reason I ask is two fold. First of all, the only "signs" I think I have ever had with my hand loads is VERY small primer cratering. I am talking very small here. Once I see that, I don't go any further.
The second reason I am asking is for safety. I have read in the reloading part of this site that Saeed will sometimes have a hard time opening the bolt after shooting some very high pressure loads. To me that seams like WAY too much pressure. I always though that once you get to that point you are getting close to blowing up your action.
If you can educate me further on pressure, I am all ears.
Thanks, this site is great!!
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Monyhunter
The radius of the primer edges also has more to do with the headspace of a particular brass case in your chamber than with pressure. Low pressure loads fired with longer headspace show extremely "flattened" primers, whereas higher pressure loads fired with very tight headspace may show little primer flattening at the radius if the primer cups are "hard" or thick.
First indication: Sticky bolt lift. This will happen before bolt face imprints.
Second indication: Expanded case head measured at the rim or belt. This is tricky to measure, and remember, the original case may not be perfectly round so you have to measure at a pre-referenced place. I don't even start to believe that guys who claim they can measure 1, 2, or even 5 one-thousandths inch expansion. But if you get measurable expansion, you load is too hot.
Third indication: Losened primer pockets. Directly related to above, but easier to detect, especially with a hand seating tool, which you should always use.
Fourth indication: Case head engraved with mirror image of bolt face, such as ejector hole or slot mark, etc. If you see such, you are definately too hot (and probably had to use a rubber mallet or the heel of your shoe to hammer the bolt open).
Finally, look at the pressure ring near the head where the brass becomes thick enough that it does not expand to fit the chamber, but holds the pressure itself. On lighter loads, this ring will be further forward (toward the mouth of the case). As pressure goes up, this ring will move progressively rearward toward the head. There is no "gauge" or objective measurement for the pressures involved, but using new brass from the same lot, the pressure ring will be further aft with higher pressure loads than with lower pressure loads.
There is a tremendous margin of safety with modern bolt actions. Even with weaker action types, the brass case usually gives up long before the integrity of the action is breeched. So, what you worry about with high pressure is how does the action handle the high-pressure gas spewing from the primer hole or from a crack in the case head (not about the bolt lugs shearing off and sending the bolt back through your cheek). And in practical terms, you worry about slick feeding and not having to hammer the bolt open as that wounded elk tops the ridge on its way to the next state.
The most practical way is to measure case expansion at the junction of the case wall and solid head. Get a base line from factory ammo. Measure to four didgits with a mic. Do this at several radial loctions, pick the largest one. Your chamber might not be perfectly round. Ok, now you have measurement like o.4735". Check your handloads the same way. Those that give a measurement of 0.4735" are the same pressure as factory. Larger is higher pressure samller is lower. For most cartriges I load to factory pressure. SAMI and the factory boys have more resources for load developement that we can imagine. I figure that I want safe ammo that shoots straight so I make it like they do.
Measuring the expansion at the rim is probably not the best since by the time the solid head is flowing you have gone way to far. Primer eyeballing is un-reliable for many reasons. Sticky bolts fore tells bad stuff, that is way to hot. I am a bit skittish about pressure. I have trashed a couple of rifle by eyeballing and winging it. Since I started doing it his way, I have not had a single primer fall out or a bolt get sticky. Best part is that you can plot your pressure against velocity and see trends and avoid disaster. You will actually see velocity gain slow as you increase the charge past a certain point.
Check out "Pet Loads" by Ken Watters, it goes in to detail regarding this method.
As the material changes its properties (elasticity, thickness of walls) with continuous firings, the procedure is not as simple as it seems to be, and it needs the experience of a Ken Waters who could judge by measurement how hot a cartridge had been loaded.
Primers can tell you something if components are routinely used but, as stated above, they can be misleading.
Knowing your factory load pressure ring dimensions and using them as a barometer is a good way to go. With belted cases, I have a jig that allows consistent measurement of the forward half of the belt only, which serves the same purpose as micing the pressure ring on beltless cases. Ken Waters' system is a good one but it relies very heavily on the consistent use of specific components, for which, one will "get a feel for" over time.
Bob Hagel had a similar but more aggressive system which was better suited to the belted magnum cases. His is the method I use most, with a bit of my own stuff, thrown in.
I recommend Hagels' book "Guns, Loads & Hunting Tips" along with Waters "Pet Loads" mentioned above.
The only "rule-of-thumb" I'm willing to use when I suspect excess pressure is getting close is to reload the same case 5 or 6 times with a load....if the primers still seat firmly I don't worry. If the pockets show any sign of becoming loose I back off.
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Ray Atkinson
[This message has been edited by scot (edited 10-17-2001).]