Excess Pressure - Request for Pictures

[Koa]

I'm getting back into reloading after being away for several years. When I reloaded previously, I never really had a good method for working up loads. After doing some reading on here I've decided on a method. As is always recommended I'm going to start from the bottom (charge wise) and work up.

As I embark on this method I know I need to be careful to look out for signs of excess pressure. I've read about them, seen a few black and white pictures, and seen pictures of full on case failures. Problem is, I'm having a tough time picturing what some of the signs actually look like on the lower end of "too much."

Anyone out there have some good pictures I could consult to get an idea of what I’m looking for?

 

[joelkdouglas]

Do you have a chronograph? The best sign of excess pressure, without a pressure gauge, is measuring velocity. If you get velocities higher than "max pressure load" velocities, you've likely exceeded max pressure.

I believe you don't start seeing ejector marks until about 68,000 or 70,000 psi, and those indications are unreliable.

 

[Oldtrader3]

Using a chronograph is how I judge my handloads for pressure above any other method. I have been handloading for nearly 50 years now and am very careful not to have any loads that are running on the edge of being too high pressure or even showing signs of high pressure at any time. I stop adding powder long before that point is reached.

Usually a particular rifle will shoot good groups when the velocities are the most consistent for that group of components. The best way to check that is with a chronograph. I also tend to use the same loads that work well and accurately in my rifles for a long time and do not do continuous load development once I find a combination that gives me consistent and accurate loads.

Plus, in my entire loading experience, I do remember creating more than a few cases that showed any pressure signs at all. I immediately backed off and did not make any more of these cases, when that occurred. I would not have even tried to take pictures of them or create more by loading higher.

 

[DrMike]

The best sign of excess pressure, without a pressure gauge, is measuring velocity. If you get velocities higher than "max pressure load" velocities, you've likely exceeded max pressure.

I believe you don't start seeing ejector marks until about 68,000 or 70,000 psi, and those indications are unreliable.

+1

By the time you see signs of excessive pressure, you're already over. The best advice is to stay with a good recipe that has been pressure tested. As you gain experience, you will eventually recognise pressure signs intuitively (change is report, sticky bolt lift, etc.).

 

[6mm Remington]

Dr. Mike, Joel, JD338, Brian, Scotty, Guy, Kurt, nvbroncrider, (many others too numerous to list) and some of you experienced guys tell me if this is correct also. I have read and feel that if I am going along starting light and working up a load and each load is 1/2 grain above the previous one, If I am getting consistent 30-40 fps increase or there-about's for each 1/2 grain of powder increase, and I all of a sudden get a 100fps increase, I likely have just hit a pressure spike and am at maximum or slightly over, and that load should be reduced by at least one full grain. I have never noticed this with low end or medium range loads shown in manuals, but only as I approach or am slightly above what they show for the rifle the loading manual is chronographing the loads in. I also feel that you might be getting into no-mans land when your next powder increase does not show any fps increase or only just slightly, and then the next 1/2 grain increase shows a big jump in velocity.


Like Dr. Mike, a lot can be felt by how the bolt lifts or the action opens after firing. Is it comparable to a factory load or a known safe load in that rifle? It's after the fact, but if you cases are only lasting for three loadings and your primer pockets are expanding to where the new primers are seating to easily, or the cases take a bit more pressure on the reloading press (which can be felt), then that is too hot of a load, even it it does not exhibit typical pressure signs when you shoot that round.
Is that a fair assessment in your opinions?
David

 

[Oldtrader3]

Yeah, I would say a sudden, bigger spike in velocity and some "s" deterioration in velocity spread consistancy, shot to shot. When I see that, I am done. Some rifles with longer freebore (i.e. Weatherby) don't show bigger velocity and spread dispersion that same as a standard chamber. For my Mark V, I use stiffer bolt lift changes and marks on the case from the ejector clearance hole.

 

[6mm Remington]

Yeah, I would say a sudden, bigger spike in velocity and some "s" deterioration in velocity spread consistancy, shot to shot. When I see that, I am done.

I knew you would know the answer to that Charlie same as I expected from those other wise men I listed. Lots of good folks with a ton of experience on here. I'm like you in the fact that I like to fine "the one load" for each rifle and I quite and am quite happy! That is all I need. One good one for each.
David

 

[nvbroncrider]

Yeah, I would say a sudden, bigger spike in velocity and some "s" deterioration in velocity spread consistancy, shot to shot. When I see that, I am done.

I knew you would know the answer to that Charlie same as I expected from those other wise men I listed. Lots of good folks with a ton of experience on here. I'm like you in the fact that I like to fine "the one load" for each rifle and I quite and am quite happy! That is all I need. One good one for each.
David

Except the 6mm Remington!

 

[6mm Remington]

Yeah, I would say a sudden, bigger spike in velocity and some "s" deterioration in velocity spread consistancy, shot to shot. When I see that, I am done.

I knew you would know the answer to that Charlie same as I expected from those other wise men I listed. Lots of good folks with a ton of experience on here. I'm like you in the fact that I like to fine "the one load" for each rifle and I quite and am quite happy! That is all I need. One good one for each.
David

Except the 6mm Remington!

Okay, I'm a weak man. I do have three rifle to load for in 6mm Remington though so does that count as an excuse?
David

 

[Oldtrader3]

David, no foul, no crime certainly. I am just more inclined to use another caliber for a different load with a different bullet diameter. Part of that is mental laziness on my part. That way I only have to remember one set of numbers for each rifle, instead of several. I guess it just depends on how many rifles that you have. Both systems work fine!

 

[Guest]

In the spirit of the original request, I'll include a couple of pictures I have of some over-pressure signs. The first is ejector marks on the casehead:

Notice the ejector marks all around 8 o'clock on the case heads? These are faint ejector marks, and didn't even shear to a shiny finish when I opened the bolt. I felt resistance on the bolt when I was opening it, though, and my usual check of the case found these faint marks.

Picture number two is not as well focused, but if you look at the primers, you will see the raised ridge around the firing pin of a cratered primer:

Again, these are not horrible, but they are cratered. Look back at the first picture and you'll see the ring visible on the primer, as well.

I hope these are helpful. As others have said, the single most valuable tool is a chronograph. You can get a decent one for $80-120 if you shop around. If you have the funds, you can spend several hundred dollars if you want more features.

 

[PJGunner]

Dubyam. This is not to contrdict you in any way but I have a Remington M700 BDL in 30-06 that will do cratered primers even with light gallery loads using 5.0 gr. of Unique and a 115 gr. cast bullet. :shock: It took me a while to figure that one out but the hole for the firing pin looks like it had been chamfered at the factory. :?: It had to have been done at the factory as I bought that rifle brand new in the box at J.C. Penney for a great price ($110.00) when they were getting out of the gun business. it was discounted a whole bunch plus my wife worked there so I got another 10 percent knocked off. Other than that, the gun shoots just fine.
One thing I have noticed lately though is some of the factory ammo for even mildly loaded rounds will sometimes crater the primers. I ran into that with some Winchester 7x57 ammo with 145 gr. bullets. Now they chronied right at where they were supposed to so I'm thinking, is Winchester using ball powder in those loads and could that powder sift down through the flash hole and could that powder, if actually there, create higher pressure within the primer area causing cratering or flattening of the primer? It wouldn't more than a few granules to cause that to happen, I'm thinking. My usual powder for the 7x57 is W760 and I get cratered and flattened primers on occasion with loads that are only half way to the maximum. I don't get that with H4350. Velocities with the W760 and those cratered/flattened primer are right in line with the shots where primers looked OK.
Might be something to think about.
Paul B.

 

[shoots_5]

I'll add a note to the cratered primer picture....that depends a lot on the rifle and its firing pin. I have a rifle that will make that mark in any cartridge you put in it. Drove me nuts when I first started loading for it and thought I was getting pressure at minimum loads, and with factory loads. Just wanted to throw that in there that a cratered primer can be caused by the rifle and not by pressure.

 

[DrMike]

Don't depend upon cratering to indicate pressure. The previous posts are correct in noting that some rifles showing what most would call cratering, and it is indicative of nothing at all. Other rifles I have shot show no cratering despite giving significant brass flow. Cratering can be an indicator, but not necessarily.

 

[RiverRider]

Pressure is what produces velocity, and knowing the velocity yield of a load and comparing it to a reasonable prediction is a whole lot better than trying to interpret visible pressure signs on brass and primer. Even measuring case head expansion (IMO) is problematic because the hardness of brass could vary from manufacturer to manufacturer or even from lot to lot making the method valuable only for relative comparisons between different loads using the same brass.

The best answer is a chorongraph.

 

[Guest]

I will agree wholeheartedly that cratered primers are not, by themselves, a sign of dangerous pressure. But they can be a sign, and a good photo (okay, a fair photo) will allow recognition when they occur. Once you find them, tracing down whether it's pressure or an enlarged firing pin hole, or a weak firing pin spring, or soft primer cups, or whatever, is the key. But knowing what they look like is the first step.

In the case of the primers pictured above, I'm pretty sure they were a sign of pressure, as the starting loads didn't have craters, this load did, and the next load had ejector marks. That's a clear progression for me. Velocity was right in line with where I expected it to be, so from that standpoint it didn't strike an alarm note, but with cratered primers and sticky bolt lift, I took notice. I also tested this load with a different primer and got the same results, so I pursued a different powder for this rifle. It's all about learning how your rifle performs.

 

[tjen]

Great to have a forum where you can get sound advise like this forum.

I have to ask, do you have a reloading manual? If not stop reloading untill you do and have read it cover to cover. Their full of pictures on every thing you need to know before you reload.

With that said I have not seen any signs of pressure from any of my hand loads but stop if the velocity hits max listed. I have seen cradering on the 221rem but had very round primer edges, but I did have chamber marks on the case too. The bolt opend easy and the case fell out and can be rechambered easy too. You can have faster than listed velocity in some cases my 35rem and most I know will get 100fps more than the list hornady max. with out any hard extraction issue which is the first sign of pressure with its lower pressure spec.

I was give some brass (twice loaded) and I saw first hand what ejector marks look like and these had two each. I tossed them they had two clearly over pressure loads shoot in them. I could feel the heigth differance with my finger too.

To much velocity, ectraction issues, flatend or cradered primers. It only get worst after that.

 

[Koa]

I haven't invested in a chronograph yet, and am working up loads with an autoloader (M1A). I do have a few reloading manuals (and have read them), and so far have stuck to the components (brass, primers, ect.) and charges listed. I think until I get the chronograph, I’ll just have to keep my eyes and ears tuned for anything unusual.

 

[Oldtrader3]

You don't want to shoot loads that are too high in pressure either in a rifle which is a semi-automatic action. This is partially at least, because you want to promote easily chambering of rounds and full action bolt lug seating. Some shooters with semi-autos even use small base, die sets for full length resizing brass if they are going to reload for a semi, in order to promote easy chambering.

 

[tjen]

You don't want to shoot loads that are too high in pressure either in a rifle which is a semi-automatic action. This is partially at least, because you want to promote easily chambering of rounds and full action bolt lug seating. Some shooters with semi-autos even use small base, die sets for full length resizing brass if they are going to reload for a semi, in order to promote easy chambering.

I think some manuals might list loads just for the Garand. Or at least comented on loads for it. H4895 seems to come to mind as a good powder for it. Do you load for the garand? I thought you may have post on it once.