Pressure Signs?

[Steve1]

I watched a you-tube video yesterday on pressure signs. The main thing shown was to watch for any form of shininess on the case head. At the first sign of this, one is supposed to back off a half a grain.

The problem is that both my 300 Win. Mag. and 270 both shoot the most accurately near maximum loads. There is just the beginning hint of shininess on the 300 loads and a little more than that on the 270. I haven't noticed much difficulty in opening the bolt. The primers are fairly flat. I really hate the idea of starting a new search for a magic load. I recently shot a 1/4 inch, four shot group, with the 270 at 100 yards. The 300 is grouping about 3/4 of an inch at 100. I think with a little tweaking I can get the 300 down to about a 1/2 inch.

I was wondering what you think....Are these loads too hot? I'm willing to sacrifice a little shorter life on my brass. I appreciate your advice. Many of you shoot a lot more than I do....

 

[The Lawn Ranger]

Post pics of the case heads. I get a little extractor scuff on my 7 wsm
and the primers flatten out slightly as well.

You should try to figure out (Quickload) if the pressures are acceptable
for both loads.

 

[rduckwor]

Well, I don't think I would rely on a shiney spot or ring to help me figure out pressure .

Sizing dies can leave what appears to be a case separation ring due to the fact they simply don't size the case all the way to the base or web.

Take a paper clip and bend the tip 90 degrees; just a little short segment say, 1.5-2MM. Run that inside the case and "feel"
for a groove down near the base of the case.

That's where separation begins.

Otherwise, sticky bolt lift, difficult extraction, are good signs of excess pressure loads.

 

[Steve1]

I guess I didn't explain this very well. I'd send a picture but I'm kind of computer stupid and haven't figured that out yet. The shiny spot is on the case end surrounding the primer. It was made by the extractor and bolt face. I know the ring you are talking about. I really do need to check that out too with a paper clip. I've been reloading for years, and have known that trick for years..... but I've never actually done that. I usually find some newer brass before I have reloaded a case too many times.

I did have a case head separation one time.....I hate to say it....You'll probably think I'm really stupid when I tell you this....but one time, I got my powders mixed up.....I guess I'm lucky I didn't blow my head off.....I did learn an important lesson with that though......I always label everything carefully now.....It won't happen again.

 

[HodgdonExtreme]

Pressure doesn't cause CHSs, though it can cause an incipient one to let loose slightly sooner.

As far as I'm concerned, the gold standard maximum permissible pressure (assuming a modern bolt action rifle) is brass flow into the ejector hole of the bolt face. If the brass is flowing, it's yielding. If it's yielding, you're [considerably] over SAAMI.

Primers can be ignored, that is, until you've gotten quite accustomed to your particular rifle and the primer/powder/brass you use to load for it. Once you've learned your combo, inferences can sometimes be made from reading primers.

Stiff bolt lift is an artifact resulting from the aforementioned brass flow, assuming you have nicely sized brass prior to firing.

I should mention by "gold standard", I am assuming you don't have pressure instrumentation, or good, solid, published load data to work with.

 

[milo 2.0]

Well, I don't think I would rely on a shiney spot or ring to help me figure out pressure .

Sizing dies can leave what appears to be a case separation ring due to the fact they simply don't size the case all the way to the base or web.

Take a paper clip and bend the tip 90 degrees; just a little short segment say, 1.5-2MM. Run that inside the case and "feel"
for a groove down near the base of the case.

That's where separation begins.

Otherwise, sticky bolt lift, difficult extraction, are good signs of excess pressure loads.

I'm with Hodgdon extreme on this, your brass should show an ejector mark long before your bolt handle is hard to lift, unless your brass was tight when you chambered it, but if that's the case, you should have never pulled the trigger?
I've seen small primer Lapua brass that will only cough up primer signs, starting to rupture, or pierced primers, and even this is tricky. Sometimes firing pin work or change can alleviate this.

Anyone relying on a stiff bolt for pressure signs is living on the edge.

 

[rw496]

As far as I'm concerned, the gold standard maximum permissible pressure (assuming a modern bolt action rifle) is brass flow into the ejector hole of the bolt face. If the brass is flowing, it's yielding. If it's yielding, you're [considerably] over SAAM.

Do you have a good pic of what this looks like?

 

[HodgdonExtreme]

Do you have a good pic of what this looks like?

This one is heavy duty...if you can catch a fingernail on the raised "button", you're WAY over.



These are not acceptable, but not as bad... Bottom left case, just ahead of the ".308", and bottom right, just after "Lapua":




Some brass is harder than others, meaning some cases have a higher yield strength than others. You're load should NEVER be in excess of the case yield strength. If you're seeing ejector marks like these, back off.

Note that these primers have radiused corners, are not particularly flat, and show little/no cratering around the pin indent - despite being significantly over pressure... you can't go by "reading primers"!

Also note different rifle designs have different shaped/sized ejectors, so they won't always look *exactly * like these. These came from a Savage. A Remington is similar, but the button diameter is bigger, and won't totally fit on the case head - instead it'll appear like a "half moon". Winchesters aren't round, they're square.

 

[milo 2.0]

This one is heavy duty...if you can catch a fingernail on the raised "button", you're WAY over.

http://i138.photobucket.com/albums/q243/stimpsonjohn/1327293361.jpg[/IMG][/URL]

These are not acceptable, but not as bad... Bottom left case, just ahead of the ".308", and bottom right, just after "Lapua":




Some brass is harder than others, meaning some cases have a higher yield strength than others. You're load should NEVER be in excess of the case yield strength. If you're seeing ejector marks like these, back off.

Note that these primers have radiused corners, are not particularly flat, and show little/no cratering around the pin indent - despite being significantly over pressure... you can't go by "reading primers"!

Also note different rifle designs have different shaped/sized ejectors, so they won't always look *exactly * like these. These came from a Savage. A Remington is similar, but the button diameter is bigger, and won't totally fit on the case head - instead it'll appear like a "half moon". Winchesters aren't round, they're square.

To me, could be the pic, but 1,3, and the whole bottom row show signs of cratering????

 

[Clark]

I back off two grains from the threshold of primers falling out or stiff bolt lift.
The brass is too cheap and my time is too valuable to worry about how many uses I will get out of each case.

When I practice, I shoot 30 rounds a day.
When I hunt, I sometimes shoot one round per season.
I have a lifetime supply of 270 and 300WM brass.

 

[Steve1]

My brass don't have a raised ejector nub, but they do have a slight shiny mark. Maybe I better back off on the powder charge until that disappears.....I just really hate to go back to a load that isn't as accurate. A half a grain lighter and my 270 groups about an inch at a 100 yards. With the load I have now it groups about a 1/4 inch.

It's taking me over a year of testing to get the loads I have now. I also don't want a load that is accurate and slow going down range. The slower the bullet, the more it will drop at longer range. I have lot's of published load data. I know these loads may be hot. I'm just wondering how unsafe they are....I appreciate your advice on this. Is a slight shiny mark really that big of a danger?....I really appreciate your advice. If you say back off I'll start my search over again with probably a different powder.

 

[milo 2.0]

I hate to give this advice, but you may be fine if your ammo never gets temperature warm. Range days keep it in a cooler. While hunting???

I think if you backed off, messed with seating depth, you could bring the load in.
I've ran some questionable loads, but my shooting situations are controlled, and am always aware of the if's. It warms up hunting, sun beating down on metal, ammo collecting body heat?

 

[Steve1]

Thanks Milo 2.0. I think my bullets are a tad too long, and I've been using a crimp that may be excessive. I'll do some experimenting. I usually hunt in cold weather.

 

[milo 2.0]

Thanks Milo 2.0. I think my bullets are a tad too long, and I've been using a crimp that may be excessive. I'll do some experimenting. I usually hunt in cold weather.

Just by losing the crimp, you may reduce pressure. I have to ask, why crimp? I've seen gas gun loads come about with a crimp, but I feel as though it has more to do with consistent neck tension than anything else.

 

[Steve1]

I was having trouble with not enough neck tension after resizing. I started using a Lee crimp die to help hold the bullet in, better. I have a long throat on my Remington rifles. Most of my handloads are almost touching the rifling. I'm going to sand down the expander ball slightly, on my resizing die. I can probably quit crimping then. I have started to use less of a crimp, and I don't think it affects the bullet any.

 

[LawnMM]

Get a Redding neck die to adjust neck tension

 

[bruddah]

Tag

 

[punkwood2k]

Does anyone have a copy of QuickLoad that can run some numbers for me? I get ejector marks on almost every load I use.. Raised enough to feel with your fingernail, and NONE of my loads are at Book Max according to Lymans.. I get those ejector marks on almost every round, for 700+ rounds through my R700 so far, so I've come to essentially ignore them since I'm not pushing published max loads, and over 0.10" off the lands.

 

[mtrmn]

Does anyone have a copy of QuickLoad that can run some numbers for me? I get ejector marks on almost every load I use.. Raised enough to feel with your fingernail, and NONE of my loads are at Book Max according to Lymans.. I get those ejector marks on almost every round, for 700+ rounds through my R700 so far, so I've come to essentially ignore them since I'm not pushing published max loads, and over 0.10" off the lands.

I don't know about a bolt gun, but I got these pressure signs in an AR when I was bumping the shoulders back too far and getting a self-inflicted problem with excessive headspace. The load was well within specs, and I backed out my sizing die a little and the problem went away.

 

[punkwood2k]

I don't know about a bolt gun, but I got these pressure signs in an AR when I was bumping the shoulders back too far and getting a self-inflicted problem with excessive headspace. The load was well within specs, and I backed out my sizing die a little and the problem went away.

I am bumping my shoulders back between .002 and .004, Cases are max length 2.013 at MOST.. So I dont think that could be the problem.. ??

 

[mtrmn]

I am bumping my shoulders back between .002 and .004, Cases are max length 2.013 at MOST.. So I dont think that could be the problem.. ??

No doesn't sound like your problem if you're only bumping that much.

 

[Jackomason]

So I've been reading through but it seems like some mixed ideas on what's serious. I've started load development on a 7 mag, and I made the mistake of using hornady brass and it seems like its giving me indicators out the wazoo...

I'm using 162gr eldx & H4831, not ideal, but I was hoping to get me to 2900fps but even down at 2825 I'm getting ejector marks. I pushed it close to my goal but I'm not really liking what I'm seeing. Do I just back it off more or should I try a powder better suited? Say H1000?

Also how do I stop the carbon build up on the neck? Even at my starting load I had this problem.

 

[918v]

My 300WM shows pressure signs prematurely with heavy bullets close to the lands. Back off the oal.

 

[Xander3Zero]

Also how do I stop the carbon build up on the neck? Even at my starting load I had this problem.

Isn't the carbon buildup on fired necks just an unavoidable consequence of neck clearance, and that the carbon residue makes its way onto the outside of the necks before the neck expands and "seals" the chamber?

 

[Milo 2.5]

Isn't the carbon buildup on fired necks just an unavoidable consequence of neck clearance, and that the carbon residue makes its way onto the outside of the necks before the neck expands and "seals" the chamber?

This^^^ carbon on the necks indicates sealoff points. Now if carbon makes it's way to the shoulder, now you have issues because buildup here messes with your headspace.

Way to dig up an oldie, lol

 

[Xander3Zero]

Lol, someone bumped it up prior to me...

I was more just curious about carbon residue on the necks and if there were any guidelines/rules of thumb/methods as to how far down the neck the residue should go, or if any specific practices can reduce this buildup, or if it is pretty much guaranteed.

 

[Milo 2.5]

Lol, I knew you didn't bump it, I just stated your advice was correct. In the sequence of firing, gas takes the path of least resistance, it's coming back at you, the neck sealing off prevents us from getting a face full. That is why neck clearance in a chamber is important, too much no good, too little and you have pressure.

 

[Jackomason]

Sorry, had to resurrect it! Seems like a good group of knowledgable pressure people.... didn't want to start a new thread onthe same topic!

I think I'm going to run to town and pick up some H1000 today, I'll aim for 2900 and hope my case can deal with the lower pressure at that speed. What do you guys think?