223 reloads

[xtry51]

This is what I'm talking about when I say "flattening" the primer. This a fired next to unfired 77gr Sierra HPBT over 24.5gr of Varget. If you look at the perimeter of the primer, the radius has gotten smaller on the fired cartridge when the primer was forced against the bolt face. This flattening is the first sign you are approaching max safe loads.

(Pics are from my rounds)




The next danger sign after flattening is "cratering". This is when the primer begins to mold itself around the firing pin causing metal to flow into the tiny gap between your bolt and the firing pin. It creates a raised lip around the primer strike that makes the strike look like a meteor impact crater. It can be felt when dragging a fingernail across. If you see this happening STOP and back your powder load down.

(Pics not mine)




If you load beyond primer cratering you will pierce a primer and damage your gun when the hot gases escape thru the primer shell and melt your bolt face or firing pin.

 

[M1911a1g17]

@xtry51 thank you! I have only had cratering once with Hs-6 on a 9mm. I have noticed that 357 magnum tends to flatten no matter what. Even on factory loads I have shot. Is it safe to test with how it ejects from the cylinder with that?

 

[xtry51]

@xtry51 thank you! I have only had cratering once with Hs-6 on a 9mm. I have noticed that 357 magnum tends to flatten no matter what. Even on factory loads I have shot. Is it safe to test with how it ejects from the cylinder with that?

Flattening amount and onset can vary a lot with primer brand and cup thickness. If you load some identical bullet/powder load/brass rounds with CCI400s and others with CCI41s, the flattening will not be the same even though the load is.

Ejection ease can be related to things outside of loading so I wouod be careful conflating the two. If you aren't resizing your brass enough, yoy can get high extraction forces without high loads and vice versa.

The primer tells you the best knowledge as it is 99% of the time the weak point. There are some exceptions on fatigued brass and being able to identify when that brass should be thrown out, but that is a different topic.

My advice is pick a primer brand/model for each caliber you are loading and don't change it. You'll learn more and be safer.

I only use CCI400s for 9mm and 223.

 

[akma]

@akma Yes it is for sure!! I have some varget. Do you crimp? If so how much? What does that tool do exactly? I just looked at the link and saw it makes sure for uniform seating depth. How does it do that?

I crimp only 55/62 FMJ.

It establishes where the bullet in relation to the lands. When you are using different brands and types of bullets if you record the seating depth of each you can return to that dimension if you change your die setup. It is essential for accuracy development.

As @paul73 said Varget is for 69/77 gr bullets. I can easily cover 5 shots @100yds with a dime.

 

[M1911a1g17]

@xtry51 that is good to know. I was under the impression that with 357 mag that was a good tell to overpressure as well. I have been trying to do that but also getting what I can primer wise. It’s been tough!

@akma thank you! That is very good to know. I am going to try to pick one up. Saw them in stores before.