Do these primers show signs of high pressure?

[fguffey]

"Do these primers show signs of high pressure?"



Rmeju, you need to compare the diameter of the case head with with the diameter of the case head before you fired them, you need to measure the diameter of the case head at the bottom of the extractor groove with the same case before you fired it. Then there is the diameter of the flash hole before and again after firing.



Then there is the standard, meaning there has to be a base line when comparing. At one time factory ammo was used, the factory case head was measured before firing and again after firing, the difference in the diameter of the case head was the standard. The difference was .0002" + a little. 5 firings would results in a case head diameter increase of .001",



Scary, I have measured case head expansion of from .007 to .011", some of the shooters have asked me to if I had the other shell holder, meaning the case head expansion prevented the cases from fitting the shell holder without using a case friendly hammer.



F. Guffey

 

[Rmeju]

@Gamestalker: I measured the chamber using the Hornady chamber gauge and a 162gr A-Max bullet, which showed 3.755" for me after several measurements on 5 different bullets. I measured using a comparator to get a measurement off the ogive. I measured every single round to make sure none went into the lands. Every round was powder trickled to exact charge weight, working up in 0.6gr increments to get to the next charge. I chambered a few to make sure no rifling marks showed up on the bullets. While I was at the range, the bolt worked like butter. No problem lifting it that I noticed. I don't have a problem seating the rounds I have a hair deeper if that will make them safe, I just read that seating up close and personal was common, and even preferred. If I'm wrong, just let me know.

@fguffey: I have some unfired rounds I can check. It's not the same thing as the actual round, but maybe it can give me a rough idea if there's some kind of major enlargement going on. Assuming I won't ruin my gun by shooting a few more, I can check the before/after of the unfired rounds next time I go out. Honestly, my caliper doesn't go to 4 zeros, but I might know someone that has one, so I'll check it out.

@Arch: You're right. The bullet wasn't in post 11...actually your post alerted me to the fact that I inadvertently left it out. I couldn't figure out what the heck you were talking about in your post until I went back and looked, and sure enough it wasn't there, so I corrected it. I didn't mean to be sneaky, although looking back, I can see how it might have appeared that way. I'm really just trying to figure out if my loads are safe, and if they are not, I simply want to correct the problem and move on with my load testing.

As for what I'm doing shooting the loads I listed at 100 yard paper targets, I was working up a load. Lower charges might make for more pleasant short range shooting, but I don't plan on being at 100 for long. That was my first day out, with my first bolt gun, and I figured I'd remove the variable of the longer ranges, especially since it was such a windy day that day.

 

[fguffey]

Rmeju,

“ @fguffey: I have some unfired rounds I can check. It's not the same thing as the actual round, but maybe it can give me a rough idea if there's some kind of major enlargement going on. Assuming I won't ruin my gun by shooting a few more, I can check the before/after of the unfired rounds next time I go out. Honestly, my caliper doesn't go to 4 zeros, but I might know someone that has one, so I'll check it out”

I have a Pratt & Whitney gage that went to .000005, not practice, I remove the electronics and replaced it with a dial indicator on the stylist. It is a good ideal to save a few rounds from one lot to use as reference, as to the 4 places to the right, when developing a load a .001” case head expansion should get the reloaders attention.

F. Guffey

 

[Rmeju]

Thanks for the help.

I'll do some more poking around to see what the other signs of high pressure are. I see that primers aren't, but I guess I'm still not sure how everyone else is using velocity and bullet weight to determine pressure, or to figure out when seating close to the lands is a good idea vs. when it creates undesirable pressure.

 

[scottishkat]

I shoot 70 g H1000 in my 257 wby

You can use the 7mm RM brass to make 257 wby. I would not be worrying about 64 g H1000 in the 7MM RM max loads are 5 or 6 grains over that. As stated by others when you shoot lighter loads of magnum rifles you can create higher pressures hornadays data is on the light side IMO. That's a great cartridge you didn't buy it to shoot light loads.

 

[243winxb]

Pressure Signs

http://www.shootersforum.com/handloading-procedures-practices/58763-pressure-signs.html These are the main ones. Look at link for others.

1. Case bulging, particularly near an unsupported part of the head.
2. Case head expansion may mean high pressure (for the brass), but an isolated example may mean nothing as the pressure that causes it can vary 2:1 from case to case).
3. Case primer pockets getting loose in five reloads or fewer.
4. Case, extractor or ejector marks on head, especially after increasing powder charge.
5. Case, won’t fit back into chamber after firing.
6. Hard bolt lift.
7. Increase in powder charge gets unexpected velocity.
8. Primer cratering (may mean high pressure, or it may mean a worn firing pin or firing pin tunnel, or may mean you have a new production Remington bolt with chamfered firing pin tunnel).
9. Primer flattening (may mean high pressure, or may mean long headspace; some loads always make flat primers; softer primer cups (Federal) flatten more easily than harder ones (CCI), so it also can mean nothing at all).
10. Primer, piercing (may mean high pressure or may mean incorrect firing pin protrusion or incorrect firing pin nose shape).
11. Primer, leaking gas around primer pocket (may mean high pressure, may mean loose primer pocket
12. Case, sticky or hard extraction
13. Case, torn or bent rim (from hard extraction,
14. Case, primer pocket expanded and won't hold newly seated primers firmly
15. Primer, loose or falls out when opening the action

Look at photos here- http://s338.photobucket.com/user/joe1944usa/library/

 

[FROGO207]

^^^ As posted above the main thing I have noticed is not all brands of primers are made equal in respect to strength of metal. Some will flow/flatten with normal loads. I still watch them but do not use this as a really good sign of problems anymore. The above post is a great guide for the beginning realoader IMHO.

 

[fguffey]

"Primer, piercing (may mean high pressure or may mean incorrect firing pin protrusion or incorrect firing pin nose shape). "

Add to that one, the firing pin spring, it is a .7854 thing, the spring must be able to overcome the pressure inside the primer, it is does not, the pressure will push the dent out and the firing pin back, causing? a hole in the primer.

F. Guffey

 

[jim243]

Don't know, I don't use that brand of cases. The primer pockets seem a little large. Many reasons the primers would flatten, head space problems, hot charges, worn primer pockets, wrong or undersized primers, bullets being set right to the line and groves (long OAL).

Most do not look too bad, did you have any problems extracting them, that would be a tell tale sign of high pressure. If the bolt opened without any problems and extracted the shells normally, then I would not be too concerned.

Jim