What are the most common and predictable sign of excessive pressure? I know some, but any help would be great. Thanks. mvm

It is obvious that you haven't even opened up a reloading manual......

Please disregard the previous post. It is not typical of the courtesy most participants here exhibit.

Sticky bolt lift and features of the bolt face engraved on the case head (ejector cut, etc.) are sure signs of truly excessive pressure.

Signs of marginally high pressures are more subtle and less easily interpreted. Loosening of primer pockets after only a few firings is also a certain pressure indicator.

Reading primers is very difficult, but if you are familiar with the particular gun and have brass that is sized to minimal headspace, AND use only the same lot of primers, then relative (not absolute) differences in pressures can be reasonably well discerned. Of course, if your firing pin fits its hole well and your firing pin spring is not unduly weak, then a cratered (or pierced) firing pin indentation is usually the result of high pressures.

Many shooters attempt to rely on measured expansion of the case head. I don't, in that I feel that the very small increments that you must measure are too small to reliably interpret -- although many will disagree. I'm fairly competent in this area but just have never found this method to be repeatable.

All of these indicators are best used in conjunction with a chronograph. If you are getting unexpectedly fast velocities with a given load, then this MAY BE a result of unexpectedly high pressures.

[ 07-24-2002, 20:24: Message edited by: Stonecreek ]

Disregard my post hell!

The signs of overpressure are listed in every handloading manual published!

If someone is too damn lazy, or too damn dumb, to open the manual and read it, they have no right reloading!

If they are too damn lazy to research a topic before they post their silly-assed basic question, that is their problem!

There is a definate difference between an honest question from a new reloader, who has researched his hobby, and the meanderings of a cretin who want to be spoon fed every drop of information!

Take a look at the recent onset of what I consider "really dumb questions":

"What are the signs of high pressure?";

"How come I can't crimp my .44 Special loads with my .44 Magnum dies?";

"What is the magazine length of a Remington 700?";

"Givbe me all the information on the .30-06 cartridge listing all the powder, primer, case and bullet combinations, as well as all velocities and pressures.";

"Can I just fill a case with powder and shoot it?";

Need I go on?

[ 07-24-2002, 22:21: Message edited by: ricciardelli ]

Steve.....I'm with you on this one. My first reaction was to respond that the surest sign of too much pressure is when the last thing you remember before you wake up to someone picking shards of wood and metal out of your face and hands is a loud "boom" but I decided to pass as people who try these type of posts scare the hell out of me.

I'm the type that wears both a belt and braces when hunting so it shouldn't be much of a suprise when I say I purchased, read, studied and digested all of the reloading manuals I could get my hands on (as well as whatever books I could find) before I even thought about beginning to reload. It's a serious undertaking.

Pshooter asked for "the most common and predictable" signs of pressure and further stated that he is aware of some of those signs. I take it from this that he has read, from some number of sources, the commonly cited indicators, and was inquiring from fellow reloaders as to their experience and opinions of which are most useful and dependable. That's the way I took his post and the way I responded.

There are certainly some posters who ask such obtuse questions as to be valueless to themselves and of little interest to other posters. When this occurs, I ignore them rather than wasting my time and spreading ill will by responding with hostility to them.

Pshooter: I hope you get some additional useful advice. I've been loading for nearly four decades now, but my methods may not be as useful as those of some others.

pshooter: I searched the Internet and found a few sites such as the one below. It includes several pictures of cases that show excessive pressure signs.

In my humble opinion, reading from manuals alone is not enough to learn about case pressure signs, and there is where forums such as this and many others are a great source for learning.

http://www.tisbjerg.dk/ammo/diagnosing%20problems.htm

PSHOOTER,
There are many signs. All the way from mild to whoops! One of the earliest is the expansion ring on the cases body just in front of the extracter groove. The area in front of the extracter groove is the web of a case and the closer to the extracter groove, the thicker the case will be. When a round is fired, the case expands, except where the case is thick enough to resist. The portion of the case that expands to touch the chamber takes on a dull look. The unexpanded portion of the case will still have the new look. Where the new and dull look meet is the expansion ring. If the ring is 3/8" in front of the expansion ring your pressures usually are ok. As the pressures climb, this ring will get closer to the extracter groove. If it reaches the extracter groove, you're already in BIG trouble!

Conditions of a fired primer may or maynot be a acurate indicater of pressure levels. If the round edge, starts to get smaller, the pressures are climbing. If the round edge becomes square, again, you're in trouble. A cratered primer is not always an indication of high pressures. If the firing pin is excessively smaller than it' hole, a cratered primer will be the result. A cratered primer will also be the result if the firingpin spring has weakened over time. If your bolt is one of those which has the ejector in the face of the bolt, high pressures will result in the case being extruded into the ejecter hole. When the case is removed from the chamber, the turning of the bolt will result in a round shiny spot where the bolt cut the extruded brass off. If you get the shiny spot, a sticky bolt or a case that requires an effort to pull the bolt to the rear STOP IMMEDIATELY!!! You have reached the point where you are flirting with BIG TIME TROUBLE!!!

One thing that may be of some help is to buy a few rounds of factory ammo. Fire them in your rifle and keep them as a reference for pressures signs. Like STONE CREEK, I'd like to apologize for any hard feelings. We were al beginners once. Even those of use who aren't new come across things we need help with from time to time. If we can be of help, please let us know. This site has some real nice people. Good luck.

ricciardelli, I wasn't talkng to you, but you can kiss my a** anyway. As for the other replies adressing my post, thanks. I have been re-loading for 5 years now and i've seen every picture in all 4 of my reloading manuals. And as I mainly don't deviate from published loads I rarely see excessive pressure signs. Flat primers are about it. So I just thought I would tap into the vast sea of knowlege out there. Thanks for the honest replies. As for you ricciardelli...you couldn't pay ME to believe anything you have to say! mvm

pshooter, these are potential pressure signs from AccuLoad :

Primer flattened
Primer pocket enlarged
Primer pocket leaky
Primer loose
Primer backed out
Primer cratered
Primer pierced
Case expansion excessive
Case stretch excessive
Brass extrusion into ejector
Case separation
Case potential separation ring
Case resizing difficult
Case life short
Case extraction difficult
Case stuck in chamber
Case rim deformed on extraction
Bolt opening difficult
Recoil excessive
Velocity abnormally excessive

I hope this helps.

Steve...you are a prickly sob but I'm with you again on this one.

By the way steve, I went to your page with the provided link...what a joke! Sorry, just had to say that I feel much better now. I might even let you kiss me! You stupid self-absorbed peckerhead. mvm

[ 07-26-2002, 03:31: Message edited by: pshooter ]

Well, the 26,121 people who have utilized my pages so far this month, have no problems with my pages.

Maybe it is because they know how to read?

Maybe it is because they are able to comprehend what they read?

Maybe it is because the have a higher intelligence level than a third-grade used-car salesman?

Here is a related question, and before you dump on me, I have been reloading pistol for 10 years.

I always check my reloads with a cartridge headspace guage. I noticed recently that a high percentage of my 9mm reloads would not fully chamber in the guage. Upon closer inspection, I noticed a bulge just in front of the extractor groove.

In the past, I had scrounged some brass from the police range and had gotton some sub-gun brass before I knew better. Since I had to pull all of the failures, I decided to deprime and full length resize all of my brass and check them, before I made another bad batch. After I ran them through the case guage and discarded the bad ones, I reloaded as I normally do on my progressive loader.
This got rid of all my bad brass.

Now to the problem. This just happened again, with a different batch of mixed brass. I haven't picked up any more casings at the police range, so that could not be the cause. I can think of two other reasons.

One might be that I have a lot of brass in advanced stages of case failure. I usually load 9mm in either 115gr or 124gr metal clad or FMJ, at target velocities of about 900fps, so I would be surprised if a traditional overpressure were the cause. If it isn't over pressure, then what?

Anothe reason might be that, this time, I scrounged some brass at a local indoor range. Most of the 9MM pistols they rent are Glocks. I have heard that Glocks have an oversized chamber. I don't know if this is true, but if it is, this might be the reason for the bulging brass.

This is the only caliber that I have a problem with.
Any ideas? It sure is a pain to run them through the press twice.

A quick question back to you...does the "bulge" go totally around the case, or is it just in one area?

I load my 9mm a bit hotter than you load yours...

Sierra 115 JHP at 1297 fps
Lyman 121 #356402 at 1125 fps
Speer 115 JHP at 1227 fps
Nosler 115 JHP at 1384 fps

So I do not believe your problem is pressure related.

I have yet to experience the "bulge" you are referring to, but generally I use only factory new brass, except a few months ago I picked-up 2000 "processed, once-fired" pieces of brass. That was a poor experience, and will never do that again! Brass was poor quality, military crimps, AMERC brass, and some of them were obviously not "once-fired".

I did notice that quite a bit of it was fired in a Glock, and the cases were mal-formed. (Possibly due to an unsupported chamber.)

I fire my 9mm's in two Firestar Plus's, a Smith 659, Ruger BN-36X and a Ruger P85. I have noticed no "odd" cases after firing in any of those firearms.

Another post that has invited anecdotal replies from self-made "experts."

So, gentlemen, is there a correlation between casehead expansion (measured with a blade mic, to tenths) and excessive pressure ?

If yes, that correlation is :

At the risk of making an on-topic post... :-)

An excellent sign is that if you can load a case about 7 times without the primer seating becoming easier, then you have clearly not exceeded the elastic limits of the brass case. You need to be using a hand priming tool rather the priming on a press to feel the difference, IMNSHO.

Yes, it is a bit of a pain to keep track of how many times you have loaded a given case, but it ain't rocket science to do so.

I've found that several "good" loads which I arrived at by watching all the pressure signs listed above (in another on-topic post) actually allowed only 3 reloads of a given case before primer seating got a bit too easy -- clearly a load a bit over the top because it was stretching the head of the brass. The small expansion is difficult to measure with a micrometer for a single shot, but the cumulative effects of 5 or 7 shots can be felt when you seat a primer.

HTH,
jpb

[ 07-26-2002, 14:56: Message edited by: jpb ]

That particular question annoyed me because the person who posted it started his question by stating that he has loaded his ammo to be 0.015" off the lands of his rifle, and then he wanted to know if his loads would fit in his magazine! Damn! If he has the rifle sitting in his lap, and he has loaded specifically for it, he SHOULD have been able to either measure the magazine, or run a few rounds through the rifle to see if his loads fit!

As for the SAAMI pressure question you mentioned...I do not recall the exact phrasing of your question (but I will research it!). The reason the pictures are posted is because, "A picture is worth a thousand words."

(slight pause while I search)

Okay...I went back to that particular post. You had originally asked about the pressure differences between the 6mm Remington and the .243 Winchester.

I stated that I shoot both, but prefer the 6mm, and gave my loading data for each (which is well under the 65K SAAMI recommends). The picture was included because I also stated that best accuracy is not always obtained with maximum or over-maximum loads.

[ 07-26-2002, 17:59: Message edited by: ricciardelli ]

If you can measure case-head expansion in tenths of an inch (0.10") then you have gone well past anything that's safe...in fact the case is probably stuck in the chamber while the remainder of the rifle is scattered about the range.

Pardon my intrusion, but on subject again, re: case head expansion.

As I stated earlier, I don't use it because I've never been able (skilled enough? properly equipped?) to consistently measure such small expansions as the venerable Ken Waters has used for decades in his Pet Loads series -- and I think highly of Ken and his writing.

I think many people misunderstand, however, that the area of the case head that is too be measured is always in the unsupported area, meaning that the size of the chamber has nothing to do with how much expansion occurs there. Ken always used the rim on a rimless cartridge or the belt on a magnum; neither of these areas are supported and are free to expand as much as they will dependent on how much internal pressure is generated by the load.

Here are the problems I see with this method: (1) The case head may not be perfectly round to begin with, meaning that the measurement must be taken precisely across the same two points to be meaningful. (2) The generally accepted expansion is on the order of .0005", which is less than I can dependably measure. (3) The expansion will vary considerably with the same pressure, depending on how hard or soft the case head is. This WILL vary from brand to brand and probably even from lot to lot with a brand.

For these reasons, I just don't have much faith in case head expansion as a dependable pressure reference.

DB Bill
When dealing with measurments, only a carpender thinks a tenth = .10. For most people familiar with measuring equipment a tenth is read as a tenth of a thou. or .0001.
Stonecreek
Mitatoyu (and others) sell mic's that read to a tenth (.0001) directly, no interpration needed. Mine has the mechanical (odometer style) digital display on it, along with the standard spindle scale and a vernier scale for the tenth's.

Now were getting to the meat and potato's of it all! I guess my question wasn't so stupid after all! And all this is covered in chapter 438 in all my reloading manuals! Sometimes uneducated people just get in the way of progress. You guys have helped me a great deal, as there is NO load data for a 300WSM in a 15" bbl. So you got to start somewhere and where is here! Thanks to you professionals...but not to you asses. mvm

Case head expansion probably does not have enough resolution to be very precise. As sort of a ballpark, a rifle cartridge might expand in the neighborhood of .0005" at 50,000 PSI. The best you can hope to resolve is around .0001", which means your resolution is sort of 10,000 PSI'ish.

On the other hand, there has been some interesting work done that will soom appear in Varmint Hunter. The new technique involves watching how much the brass "springs back" toward its initial dimensions after being stretched to chamber dimensions. I think that this new technique will be much more satisfactory than case head expansion, and it works on firearms where you can't really add a strain gauge.

Thanks guys. But what I am wondering about is if you use powders designed to work in the longer tubes (24+") they can't be the most effecient powders to use in the shorter (16-")tubes. Published pressures won't even be close. The case expansion theories have merit to me but are still just theories. But maybe that's all there is to go on. That's what I'm trying to find out. I don't have a stress guage but I am at home with a mic. The published data i've found is for a 26" config. and is way away from the 15" pistol I want to build. Again my objective is a 15" bolt gun that will achieve 3000fps with a 150gr bullet. Can it be done safely...I still don't know, Thats why all the questions. Thanks again. mvm

Try the fastest powder thats recogmended for a rifle (in the manual, and start with the minimum charge. However even the slowest powders will have reached their max pressure in your 15' tube, and might just be the ticket your looking for.

As far as getting 3000fps out of it, I wouldn't bet on it, more likely in the 2900 range.

Without exceeding the recogmended load max, watch the velocity/gr numbers as you go up, when they stop climbing at a steady rate, your at the max charge for that combo.

Excessive pressure occurs before common and predictable signs. If you find that your unique brand of fun has to be pursued in the absence of published load data developed by experts with access to a pressure barrel/gun, I would recommend a paranoid level of caution, conservative expectations, and a chronograph, preferably an Oehler 43P. Keep telling yourself, the Oehler is going to be cheaper than a new gun and a trip to the emergency room and lost work and looking stupid.

The A-Square Manual is an invaluable source of prudent advice with regard to this issue.

If you read the work of some of the very best gunwriters over the last twenty years, you find that some of their old wildcat development finished with loads that we now know were wildly dangerous. If it were not for good fortune (one very hot day could have been disastrous) and the merely adequate safety margins to which firearms are built, there could have been one more lesson for all of us to keep in mind. One writer reported that his .45 Colt (five-shot Ruger?) revolver loads, which had seemed safe, when tested produced pressures greater than the maximum for .300 Weatherby. The same writer also liked .338-.378 loads that were 200 fps faster than the current maximum factory loads. This should not be set against the reputation of the writer. He did the best he could with the technology and standards available to gifted amateurs at the time. Old data developed without a pressure gun is suspect.

Against the vast experience of such writers, you can hope to do no better, at least not without the 43P and a calibrated pressure transducer. Try hard to be careful and cautious and to have low expectations.

Hey pshooter, Looks like a very diverse set of opinions on this subject.

First off let me say I'm not a fan of the Strain Gauge devices for knowing when your Handloads are SAFE. That is because; 1. The inherent variances involved with attaching them to a chamber. 2. I REALLY dislike the idea of having a Strain Gauge attached to the barrel of one of "my" firearms. 3. The Calibration of the entire system is done with an "Unknown" which means any decisions made concerning a Load are just guesses. 4. The actual(unknown-calibrated) Pressure information is Second Hand since it does not come directly from the actual case. 5. And the cost of the things are a bit stiff for many folks.

I also see using "Measured Velocity" from a Chronograph for the "Main Pressure Indicator" as VERY DANGEROUS. A very WRONG concept has floated around for a couple of years now that "Pressure = Velocity" which just isn't true. Pick any Hodgdon Manual and you can see where Loads of similar Pressure create very different Velocities. The manufacturing variances in Barrels, Cases, Primers, Powders and Bullets also keep this method from having a high confidence level in any deduced pressure levels for "me".

With all that said, I still think both of the above methods are somewhat useful when combined with other Pressure Detection Methods.

I've used Pressure Ring Expansion(PRE) and Case Head Expansion(CHE) for many years and have had excellent results. "BUT", they are not perfect either. Some of the problems inherent to these methods are listed by other Posters in this Thread and they are correct.

I have a File on how to use PRE and CHE that I'll be glad to send to anyone. Only problem is I'm headed out of town on Sunday and won't be back near this computer(containing the File) until sometime next month. So, if you would like a copy, post your email address and let me know you want it before Saturday night.

...

In my opinion, you should use "EVERY" Pressure Detection method available to you. And that includes Velocity and Strain Gauges if you have them, but I would encourage people to use them as Support Info only.

Tailgunner...when talking to posters who ask really vague questions I've found it safer not to assume any knowledge of the finer points of the topic...in most of these cases it isn't what they don't know that will get them in trouble, it's what they think they know and don't.

For those who still believe that "faster" powders provide better velocities in short barrels than do "slower" powders.....it ain't necessarily the truth. This has been tested and refuted many times. Here's the way it works! Pick any center-fire cartridge and chamber it in a 30" barrel and test all the powders you want to the point they reach their individual maximum velocity..ie pressure won't let you go any further. Cut 2" off the barrel and refire the same load and then continue to do it until you are down to the legal minimum. GUESS WHAT.....the powder that gave the highest velocity with the 30" barrel will continue to provide the highest velocity all the way down until you reach the minimum barrel length. AND, none of the powders used will change their relative position compared to the other powders...the 2nd fastest will stay the 2nd fastest, the 3rd etc all the way down to the slowest. The relative differences between the powder may change but the rankings will remain the same. Now there are some cartridges that do their best with "faster" powders but the WSMs aren't one of them.

So DB Bill, have you tested the 300wsm in a 15"bbl?

DB Bill
Your correct (again) on both points (powder and assuming).
Had pshooter mentioned his level of in-experance ("I have been re-loading for 5 years now") and just exactly what he was looking for ("load data for a 300WSM in a 15" bbl.") in his first post, instead of a vague boring 'never shot a gun before' begineer question, he would not have gotten a bad-attitude responce from anyone, and this whole pissing contest would have been avoided.

Tailgunner, DB BILL, and others with an attitude. I posted in exactly the manner I wanted, to try to get all the different kinds of experience that was out there. And for the most part that's what I got. What I didn't expect to get was the level of sheer stupidity and HOLIER THAN THOU ATTITUDE that shone through on some of the posts. If replying to my post aggrivated you stay the hell away. I assume that you woke up one day and were the self appointed KING of reloading and knew more than any in the known universe? As for a pissing contest...YOUasses shot the first shot. What pisses me off the most is that you assume that you know something about me, YOU KNOW NOTHING, AS I YOU, AS WELL AS ANY CREDIBILITY THAT YOU THINK YOU HAVE WITH ME !! Its a shame that a few arrogant asses like yourselves think you can impose your conditions on MY question...piss on ya! I've been nice as long as I can stand to. Sorry to you other respectable posters and to the moderator. If posting my questions pisses you off I think I'll post alot more of them ! It would bring me great joy to screw up your next few weeks!!! By the way, Are any of you SELF appointed so-called experts hunters, or do you just punch paper. If you don't hunt then you immediatlly disqualify yourself with me. Just one of MY rules. If I do succeed you can bet your sweet ass that you'll never see the load data! If you came into my business I'd through you out on your ass! Thats all for me. MVM

[ 07-27-2002, 18:27: Message edited by: pshooter ]