Question about pressure signs (flattened primers)

[DaveInPA]

I went to the range yesterday and tested some .223 loads. I worked up the batches in small increments. The load data listed 25-27 grains of Varget. I loaded 25, 25.5, 25.8, and 26.0 grains. The most accurate load was 26 grains. The bullet was seated to an overall length of 2.250". I noticed these five rounds had slightly flattened primers, which I know is a pressure sign.

Now, the question is, if I seat the bullets not as deep, say to 2.260", could that alleviate the overpressure issue? I don't want to abandon this load because it's very accurate, and it's weird that a full grain UNDER max is giving me overpressure.

Thanks
Dave

[snuffy]

I noticed these five rounds had slightly flattened primers, which I know is a pressure sign.

Reading primers to look for pressure signs is like reading tea leaves to predict the future. It's an old wives tale, something often repeated until it seems to be true.

Did you chronograph those loads? What bullet? What type of rifle? If it's a bolt gun, higher velocity WITH a stiff bolt lift, along with badly flattened primers would mean high pressure. Flatened primers alone means almost nothing.

[10 Spot Terminator]

primer flattening varies greatly even between different brands some just being softer than others. More importantly would be to look at the firing pin strike dimple on the fired primers. If you start to see a raised ring around the edge of the dent forming this is what is called puddling and is evidence of the primers definitely wanting to escape the case and warrants backing up on your powder . Look around the primer pocket at the base of the brass itself. If you see any shiney spots, hint of a strike mark of anykind again you are too hot. If you have a good micrometer or set of calipers you can measure your cases at the web before and after firing each round being sure to log them on your load data sheet and watch to see at what point they start to show noteable swelling. +1 on the reply about sticky or hard bolt lift being a definite warning sign not to fire any more of those rounds. If you do get this be sure to measure that case at the web and will give you the reading you need for your chambers upper limit for case swelling for future reference . I cant tell you how far to back that number up for your specific upper safety limit cutoff because the starting diameter of your resized brass varies from one set of dies to the next somewhat and a certain amount of case stretch is to be expected. The web is the strongest part of a case and is why to watch for the pressure signs there. If you should see a shiney ring that is forming around the case above the web this warning sign is the start of case seperation and those get the old smash with pliers treatment and go to the scrap bucket. If you are using military brass that has had the primer pockets swaged sometimes switching primers will reduce the flattening somewhat . Remingtons tend to fit a bit tighter than others and has solved loose primer jump for me in several cases, just need to keep them labled and seperated from your other rounds.

[snuffy]

Good post 10 spot, a good guide on how to read primers. But, do you know how to form paragraphs? Hit enter twice when changing thoughts, it makes reading it a lot easier.

What you call puddling, I call dimpling. It occurs at normal pressure IF the firing pin hole is chamfered or enlarged from wear. If the pressure is high enough, and the FP hole is normal, primers can flow/dimple into the FP hole, pushing the FP back into it's hole. If pressure is that high, the primer would be badly flattened as well.

[Stumper]

Dave,You said primers were slightly flattened. You called that a pressure sign-true enough. Then you talked about avoiding this "overpressure sign". I fear that you are jumping to a wrong conclusion,- it MAY be a sign of too much pressure. Some flattening is normal. The degree is an indicator of where you are at pressure wise. Brand of primer, normal operating pressure of the cartridge being loaded and the headspace tolerance of the individual firearm all contribute to "normal" primer appearance for that gun and what may be inferred about the appearance of primers in your loads.Compare to factory loadings ,compare to other known safe loads, compare to other loads in your series (you are starting below max listed loadings and working up ,right?). Primer appearance can tell you things but until you know what you are looking at and for don't jump too hastily to conclusions.

[DaveInPA]

Thanks for the replies guys. Makes me relax a bit. The cases show NO other signs of pressure. I just looked at some once fired factory brass of mine and it looks the same, so I should be good.

I also wanted to add that these are being fired in an AR-15.

Yeah, I'm working up to max. Load range was 25-27 grains. This happened at 26.

Thanks!
Dave

[bigalshootmupper]

Dave, I think this may be normal in AR's. Maybe somebody else with experience in AR's will comment. I am trying to get in reloading myself for a 308 AR. My factory loads are showing a lot of puddling. This is with Federal factory ammo. I may be wrong but I believe these primers in the Federals are soft. I had one that the firing pin punched a hole right through the primer. Bullet didn't even hit the target at 100yards and there was a lot of smoke. The primer and case looked normal except for that hole. It also may be due to the design of the AR - loose fit of the firing pin to the bolt face.

[Unclenick]

As to the original question, flattening alone, as has been said, is not a meaningful indicator of excess pressure. I've had lots of military ammo flatten primers. I would add the comment that since one of the many pressure signs is that groups start opening up due to metal stretching and introducing new moments for harmonic vibration, it is most unlikely that an exceptionally accurate load creates excessive pressure in your particular gun. The exception would be case failure preceding such a degree of stretching which could happen with bad brass or a gun whose bolt lugs had been set back and had both excess headspace and too much brass exposed. Also, keep in mind that peak chamber pressure is determined by the volume your case expands into inside your chamber, and not the size the case has been sized to before firing.

There seems to be quite a variety of terminology in this thread. For one, the misuse of the term “web” to refer to all the thick casehead brass is common, and I’ve misused it myself. The word web, by the dictionary, refers to material that connects two items or locations. For example, newsprint running between the rollers of a high speed roller press is called the web. The vertical center portion of an I-beam that connects the two outside flanges is called the web. In the case of cartridge brass it is the portion of the head brass that connects the inside of the case and the bottom of the primer pocket. If it stretches, you have a loose primer pockets (another pressure sign). You can find this and a lot of other terminology in the extensive glossary at the SAAMI web site. Measuring case head expansion or case pressure ring expansion are long used methods of detect peak pressure limits in a gun. Statistically, they don't work any better than primer flattening.

I’ve never heard the term “puddling” used before except in welding. Nor can I find any other reference to it. That doesn’t mean it isn’t used—just not in my neck of the woods. The description, a raised perimeter surrounding the firing pin indentation is commonly called cratering. That is due to its resemblance to a lunar crater with a raised crater wall. It can be due either to high pressure forcing the metal to flow into the normal small space between the firing pin and the firing pin tunnel, or at normal pressure it may be caused by an oversized firing pin tunnel or an undersized firing pin.

Another common primer pressure sign is mushrooming. This is where the primer cup expands below the sides of the primer pocket at ignition and is squashed back flat so that the head of the primer cup extends out laterally beyond the edges of the primer pocket. It can be caused by overpressure or by excess headspace letting the primer back out so far before the head stretches back at the corner of the web that normal pressure expands it.

Actual primer piercing or leaks are another pressure sign. There are plenty. But as to the OP’s question, he clearly hasn’t got there yet.

[Gun 4 Fun]

One thing I didn't see an answer to is, if you seat bullets out farther to alleviate pressure, your accuracy isn't going to stay the same in all probability. This is due to the fact that you have just introduced one more variable to the accuracy equation. Some bullet/powder/oal combinations shoot better at one depth than another. You'll have to experiment to find what works best in your particular gun with any given combination.

[dahermit]

From Hornady's Fifth edition, page 69. "These are signs of loads becoming excessive: 1. An increase in case head expansion as measured by a very accurate micrometer."
I will not list them all because you should have read them, or similar in that loading manual or another one...before you started to hand load. As you have seen, on public forums you will get some very good advice but also some opinions and/or very bad advice. You should be taking your advice and knowledge from the most reliable source...the hand loading manuals.

[Dave P]

"I had one that the firing pin punched a hole right through the primer. Bullet didn't even hit the target at 100yards and there was a lot of smoke."

That sounds like an ultra- hot load; pierced primers are caused by high pressures. High pressures move the bullet (too) fast, and that particular bullet self destructed in the air.

You sure that was a factory load???

[bigalshootmupper]

Yep, my pierced primer was definitely a factory load. Federal Power Shok 150grain soft point. I have shot about 200 of these with no problems except for that box. 2 of the primers from that same box would not fire. I tried firing them each a second time and the primer still had no indention at all. I believe this box had a batch of bad primers. I fired another box after that and no problems. I have since checked my bolt and firing pin (DPMS 308). No problems that I could see. BTW, I was shooting about 1.5MOA that day, most of that from me as I believe this gun would do way better.

[C Bass]

From Hornady's Fifth edition, page 69. "These are signs of loads becoming excessive: 1. An increase in case head expansion as measured by a very accurate micrometer."
I will not list them all because you should have read them, or similar in that loading manual or another one...before you started to hand load. As you have seen, on public forums you will get some very good advice but also some opinions and/or very bad advice. You should be taking your advice and knowledge from the most reliable source...the hand loading manuals.
Today 05:10 AM

No offense but this is the kind of response that gets under my skin. Should people not ask questions on this forum if the information they're seeking could be found in a manual somewhere? I'm fairly new to reloading and I love reading posts like this because it's very informative and contains information that I can put put in the back of my mind for when I'm out working up my loads. I have not read all the manuals but the few that I've read seem to have some gaps and certainly can't list information for every scenario and that's why I love this place. Yeah - you can get some bad info and it's up to you to be weed the good from the bad.

[Foxbat]

Actually, that was a great advice. A lot of incorrect opinion gets stated on forums like this. If it was about collecting stamps or knitting, then who cares? But reloading is a potentially dangerous activity, as anyone who has seen ruptured case or damaged gun, or worse... can testify. We all make mistakes, even after decades of doing it, and it is thousand times more applicable to anyone just starting.

What is so outlandish or extravagant about buying a readily available book that can save you from a major disappointment in your life?

[dahermit]

Yeah - you can get some bad info and it's up to you to be weed the good from the bad.

If you do not have a good background in hand loading (are new to the sport), how do you know the good from the bad?

[kelbro]

I have read a lot of 'advice' on internet forums ranging from questionable to downright dangerous.

Never read anything like that in a factory bullet or factory powder loading manual.

[C Bass]

OK guys - perhaps I've misunderstood the purpose of this forum. No more questions that can be found in reloading manuals.
I got the impression from that post that perhaps DaveInPA should not have asked this question because he should have already known the answer. I guess if we all already know all the answers... than why come here? I don't think that was a basic question that everyone should know- especially since he's shooting an AR and I would assume that maybe the signs are different when shooting an AR compared to a bolt action. But maybe they're not... I certainly don't know and that's why I enjoy people asking questions looking at the responses.

[C Bass]

I have read a lot of 'advice' on internet forums ranging from questionable to downright dangerous.

Never read anything like that in a factory bullet or factory powder loading manual.
Today 04:55 PM

Sure - that's true on any forum. It's up to you to do your own homework and use the information you get here to hopefully point you in the right direction.
So you don't ask questions on this forum or any other forums because of bad internet advice?

What is so outlandish or extravagant about buying a readily available book that can save you from a major disappointment in your life?

Foxbat - C'mon now... You got that from my post?

[bigautomatic]

A chronograph can be a valuable tool when starting to see pressure signs.

[CPTMurdoc30]

I agree what many others. Get a chrony some are under $100. I have some loads in my 223 that flatten the primer on a bottom end load and some that are smoking hot that don't show a single sign of over pressure.

I have one load with VV N133 that is pushing 3700fps with a load that is 2 gr under max.

[Unclenick]

A couple of salient points: There is bad manual information, too. Most is in the form of older manuals which have been observed to have overly hot loads. I had a starting load in the first Hornady manual for .44 Special that caused cases to stick in a Charter Bulldog. Partly that is due to the loads having been worked up in guns that were not as typical as the manual authors may have believed. Partly it is that some old information is simply out of date with respect to powders whose processes have changed. The newer manuals tend to be more conservative, but that doesn't mean you don't have to be on your toes. As has been said before, each gun is a law unto itself.

As also has been said, don't believe everything you see in print. That applies whether it is in print or on the Internet. A case in point would be Dahermit's Hornady manual quote about case head expansion as a pressure sign. Follow the second link in my first post to see actual examples of casehead expansion occurring well below dangerous pressures and also not until after entering proof load pressure ranges. It's been awhile since i read that article myself, but IIRC Bramwell showed the same exact measured amount of case head expansion caused by something like a 40,000 psi difference in chamber pressure. This was all in the same gun with brass that had the same loading history. It's another one of those things that works better in some guns than in others.

Seating a bullet out doesn't always lower pressure. For a typical medium to high power rifle cartridge there is a pressure minimum at just one seating depth. Seating deeper or seating further out from that point raises pressure. In the former case it is due to shrinking the volume the powder burns in. The the latter it is due to the bullet choking off more of the bypassing gas as it gets nearer the throat. What the minimum pressure seating depth is depends on the bullet ogive shape, the freebore and throat geometry, the case geometry, and, of course, the powder used. No generalization about its location is possible AFAIK. Just be aware that any change in seating depth could cause pressure to go up and keep your eyes peeled for pressure signs, accordingly.

[kelbro]

Sure - that's true on any forum. It's up to you to do your own homework and use the information you get here to hopefully point you in the right direction.
So you don't ask questions on this forum or any other forums because of bad internet advice?

No, what I am saying is that inexperienced reloaders should be very careful about advice posted by anonymous folks on internet forums. There is nothing better than a mentor and a set of books to reference. I have also seen tons of good advice on internet forums. Knowing how to separate the wheat from the chaff is the key. If people do not use more than one or two sources,and one of them is a message board, they are asking for trouble.

I have seen people post up loads that they know are hot in their gun. I know they are hot in my gun. Joe Newreloader, who doesn't 'have time' to work up a load properly may just take those numbers and load up a batch. I might be the one sitting at the bench next to him when he blows the bolt out of his rifle.

This post is about overpressure situations. 99.99% of us do not have known, reliable, tools to measure pressure. Many guess. Many quote some self-professed guru using the latest measurement tool that they are trying to hype and sell. Many just don't care. Either way, this can be a dangerous hobby and I would hate to see someone risk life or limb based on a post on an internet forum.

My point was that the stuff you read here or elsewhere should just be ONE data point of many that you use to formulate your loads.

[Ozzieman]

First you say “pressure signs is like reading tea leaves to predict the future It's an old wives tale,.”
Then you say “Good post 10 spot, a good guide on how to read primers.”
Then give him a hard time about paragraphs structure.
Yours would be easer to read it you would stick to your recommendations.
Saying that pressure signs on primers is a “Wives tale” is just plain wrong.
IT IS one of the best ways to tell excessive pressure and as 10 spot worded so well, certain aspects of pressure signs on primers tell a great deal and I don’t need to repeat since 10 spot said it so well.

[C Bass]

This post is about overpressure situations. 99.99% of us do not have known, reliable, tools to measure pressure. Many guess. Many quote some self-professed guru using the latest measurement tool that they are trying to hype and sell. Many just don't care. Either way, this can be a dangerous hobby and I would hate to see someone risk life or limb based on a post on an internet forum

Very true... and this seems to be somewhat of a gray area in the manuals I've read and what I've read on this forum. There seem to be few different interpretations of over pressure signs and what to worry about and what not. I think it's great that Dave was able to post his question and people are able to point him in the right direction for him resolve his issue. I was able to learn a few things to look out for in the process!
I may have over reacted dahermit's post a little and I appologize for this. I had just spent a few hours reading posts and doing some searches where I came accross a few where members had been a little less that helpful and a little too much "preaching" for my taste. I got a little worked up before I came accross this thread. I'm still new hear so maybe I should lay low