Letting pressure be your guide

[longrange772]

I have been reloading for a while, generally using Lyman manual, hodgdon site or Hornady app. Reading through some of the recipes, I haven’t been able to find loads for popular powders (e.g., H4350) that are even close to what I see in some of the recipes. Some look like they are pushing 6.5 CM close to PRC speeds. Most seem to be working up loads and watching for pressure signs (flattening primers or ejector wipe). Is there any documented guidance on what ballpark pressures those pressure signs equate to? Doesn’t seem to just be recipes found on here. I have come across pro recipes that are fairly hot as well but they may have custom barrels that can take additional pressure. Just wondering if I am missing something or people just basing loads on previous experimentation and success as to what is too much pressure.

 

[Feniks Technologies]

I have been reloading for a while, generally using Lyman manual, hodgdon site or Hornady app. Reading through some of the recipes, I haven’t been able to find loads for popular powders (e.g., H4350) that are even close to what I see in some of the recipes. Some look like they are pushing 6.5 CM close to PRC speeds. Most seem to be working up loads and watching for pressure signs (flattening primers or ejector wipe). Is there any documented guidance on what ballpark pressures those pressure signs equate to? Doesn’t seem to just be recipes found on here. I have come across pro recipes that are fairly hot as well but they may have custom barrels that can take additional pressure. Just wondering if I am missing something or people just basing loads on previous experimentation and success as to what is too much pressure.

Best bet would be to true up software like Gordon’s or Quickload (get it predicting the actual velocity or close to it), and using the pressure as a *very* general guide.

Without knowing things like the hardness of brass and such, pressure signs can vary greatly. There have been documented cases of ammo being ~20k psi over saami max and no obvious pressure signs on brass.


You’ll find that many times (especially in BR cases) many shooters are at or above the max recommended safe pressure.


I’m of the opinion that if you want to run around the top end of pressure/velocity for a certain cartridge, then you should step up to the next size. You rarely accomplish much by hotroding.

High pressure rounds and receivers excluded that is. Talking about regular receivers and regular cartridges.

 

[roostercogburn98]

I’ve never been one to head straight to the max charge of a particular round. Usually you can get good results at a medium charge on most rounds. I’m in agreement with feniks about not hot rodding. Not only does it wear out brass earlier, it’s just a tad too risky for me. I like my fingers and face where they are.

If I can’t find a load recipe in one of my books or the new online tools, I will find another powder similar in burn rate and try. I know that’s not always possible in these current times.

My opinion is playing in the pressure zone is not worth it.

 

[Supersubes]

I have been reloading for a while, generally using Lyman manual, hodgdon site or Hornady app. Reading through some of the recipes, I haven’t been able to find loads for popular powders (e.g., H4350) that are even close to what I see in some of the recipes. Some look like they are pushing 6.5 CM close to PRC speeds. Most seem to be working up loads and watching for pressure signs (flattening primers or ejector wipe). Is there any documented guidance on what ballpark pressures those pressure signs equate to? Doesn’t seem to just be recipes found on here. I have come across pro recipes that are fairly hot as well but they may have custom barrels that can take additional pressure. Just wondering if I am missing something or people just basing loads on previous experimentation and success as to what is too much pressure.

By “reading hrough the recipes”, do you mean the recipes here on the hide? If so, just ignore them, many people are just pushing too hard and either dont care about the pressure, or dont know its there.

 

[Steel head]

By “reading hrough the recipes”, do you mean the recipes here on the hide? If so, just ignore them, many people are just pushing too hard and either dont care about the pressure, or dont know its there.

 

[DarinC]

Good read for you. I know it was for me.

Understanding Pressure :: Primal Rights, Inc

Reading pressure is a required skill that all shooters must have. Whether you are shooting factory ammunition or your own handloads, you absolutely must be able to detect and interpret pressure signs on your fired brass.

rob.primalrights.com

 

[rustyinbend]

Rules for me are generally ... (a) start low, (b) work up, (c) watch for one of the key pressure signs (heavy bolt, primer craters, ejector swipes), and (d) back off slightly and test for groups and velocity nodes.

It's more "art" than "science", and every rifle/bullet/powder/load will be different.

 

[Doom]

You have to understand that looking for pressure signs is in essence testing to failure, be it primer or brass. Any of the usual signs are signs that the component is nearing failure. That said different primers may fail at different pressure, different brass different pressures. The most consistent indicator is hard bolt lift which can very from rifle to rifle and cartridge. Hard bolt lift probably means pressure are in the 70K psi range.

The maximum pressure you see indicated is a guide for manufactures to use as a mean design pressure for the production of ammunition. It is a statistically significant number and sets the maximum limit for a lot of ammunition. You should probably read the SAAMI spec to understand this.

The people that look for pressure signs and find them are above design pressure in almost all cases. If they load near these indications they typically are above the design pressure. They are operating in a range of pressures somewhere between design pressure and the failure pressure of their components.

 

[918v]

The problem is brass. There is soft brass and hard brass and in between brass. People want to squeeze out every last FPS out of their components so they load to what their brass/chamber/coal will allow. Whereas reloading manual data is based on factory coal in a minimum chamber using soft to moderately hard brass. Hardness basically acts like a pressure sensor and tells you your load is too hot. It does that by allowing pressure to enlarge the primer pocket so your subsequent primers seat loosely, and/or force brass to flow inside the ejector tunnel, and/or expand the case beyond its elastic limit and increase bolt lift effort. The harder the brass, the more pressure you can run before these signs manifest themselves.

If you try to replicate their performance in your rifle not understanding how they got to where they are, you will damage things: brass, bolt, your face maybe… There was a thread on here where a guy sheared off both lugs of his bolt and by the grace of God didn’t die. You might say it won’t happen to me but why risk it? That extra 100 FPS isn’t worth it.