Does this look like an over pressure situation?

[High Lord Gomer]

I've just started trying 3.9 grains of WST behind a 200 grain Lead Truncated Cone cast bullet with with an OAL of 1.155. I'm using Federal Small Pistol primers, which seem soft to me.

[Jman]

Yes. WST is to fast for a heavy bullet IMO. Try Unique for lead. Start at around 3.8grs and slowly work up. You need a chronograph or at least access to one.

Jim

[High Lord Gomer]

Thanks!

Forgive my ignorance, but what is it about them that shows signs of presure? Is it because they seem to have flattened out to fill the edges of the pocket? Is there anything about the marks left by the firing pin?

I've got a chrono, but I've had such poor consistency using it indoors that I'm not even bothering with it until I get a box with lights built.

[Jman]

The flatted edges and the raised "crater" ring around the striker/pin indentation.

Jim

[Jman]

Use this to compair...

Jim

[Matt Cheely]

Looks a wee bit hot there.

[High Lord Gomer]

Thanks, guys!

I really did do several searches because I know I have seen examples posted, but I couldn't find them.

I don't think I've ever seen any of my primers look that "original", Jim.

[Jeff686]

So, this might be a stupid question, but I have to ask...

How so you know this is a sign of overpressure? Is it some ancient wisdom passed from father to son since beyond time was recorded? Did someone see this in a reloading manual? If so, how old is the data?

I don't mean to be picky here, but this seems like an extremely arbitrary metric. There are so many variables at work, how can anyone possible know that this is dangerous, without actually properly measuring the case pressures? (Don't get me wrong, it is probably a good canary in a underground mine, but it isn't really telling us much else that 'maybe' the pressure is getting high.)

What is the primary failure mode of overpressure (not signs, but failures)? When and where does it occur?

If the primary failure mode is primer related (rupture, blow out, blow by, whatever) then has anyone ever tested and recorded primer appearance, starting at nominal pressures and building to failure? Have they done it for each BRAND and HARDNESS or primers? How do we know that flattening and cratering is the sign of imminent failure? Do all primers fail at similar pressures? If so, they certainly don't all look the same, since some are harder than others.

For example, I loaded up a 38 short colt to make minor in my 686. I used Federal primers, since they are soft and my 686 has light springs. A shooting friend was looking at the spent cases and got upset at how flattened they looked. He said I should switch to a rifle primer! Why? To hide the flattening? Sure, different primers have different effects, but I doubt his intent was that it would lower the pressure to a 'safe' level.

Seriously, does anyone have any real documented proof of primer appearance vs pressure levels?

[ctgun]

I am sure that there is some out there somewhere but I have yet to see hard data of the kind you are talking about. But even if you can get your hands on some of the data the difference between lots of powder, primers, the bullet seating depth and how tight the individual guns chamber is you probably won't be able get get many conclusive results from it. To me the primer shape is a good Canary in the mine as you put it. But I agree that it is a bit like reading chicken bones but unless you want to buy all the real expensive test equipment it is about all we have to go by and we all have to make our own judgements as to what pressure levels we are comfortable with. I load Major 9 some people think that is too much but I am comfortable with it.

[DougCarden]

Reading pressure signs is kinda like the Supreme Court's take on pornography.....I can't describe it, but I know it when I see it.....

Federal primers are a primer all to their own, as they are the softest, and will show what looks like pressure sings when there is not one. In revolvers, if there is sticky extraction and bad looking primers, then there is a pressure problem. Load back down until there is no sticky extraction. That doesnt mean it isnt over pressure, but is a guideline

In autos, using a primer like CCI or Winchester is a good way to watch the pressure signs. When a load is too hot, the primer will flow back into the firing pin hole, and the little tit on the primer is it shearing off in the pin hole. Too hot. For open gun loads Rifle primers are used to combat this, along with extended firing pins.

Fast powder and heavy bullets are a dicey proposition , especially in .40. The primers show flow into the FP channel, and should worry the loader. Too mas pressure. Now using Federal primers will negate the effect a little bit as they are softer and can give a false negative of sorts. It is kinda an experience thang, you will figure it out. This place is an incredible reference. I didnt heed warnings and loaded VV 310, which is my favorite powder, with 200 gr jrn loaded long to major for the nats. Really soft load, good accuracy.......blew case head on a stage.....it cleared itself and kept shooting, didnt get stopped.......kept ammo in cooler for rest of match.....Wont load that again.

Hope this helps a little bit.......

DougC

[larry cazes]

I have loaded a lot of rounds using 200 grain bullets, higher charge weights of WST, and Winchester SP Primers. I dont believe that the pressure here is any greater than the average comparable load with Clays powder which is a very common powder in 40. All things being equal, though, these primers do look quite a bit flattened and there is some flow around the firing pin impression so caution is warranted here. I have never used Federal primers, though, so I cant compare their appearance and I would not be surprised if Winchester primers looked just fine with this load and bullet. I would suggest that you get access to a chronograph before you experiment further and also work up some loads with 180 grain bullets and Winchester primers. You may prefer the loads with the lighter bullets. Loading 40 with heavy bullets and fast powders such as WST and Clays is best done using a chronograph and a great deal of judgment based on experience since any of these loads are definitely on the upper end of the pressure spec.

Edited October 16, 2008 by larry cazes

[ryan45kim]

Primers are not a reliable sign of pressure. I have friends in the industry that have pressure guns. They tested the primmer theory and found it unreliable. They had loads that were very over pressure where the primers looked fine (45000+ 40s) and safe loads where the primers flowed big time. Primers are one thing to look at but do not think they are a reliable indication of pressure.

[lugnut]

Short of expensive equipment- what do they suggest?

Primers are not a reliable sign of pressure. I have friends in the industry that have pressure guns. They tested the primmer theory and found it unreliable. They had loads that were very over pressure where the primers looked fine (45000+ 40s) and safe loads where the primers flowed big time. Primers are one thing to look at but do not think they are a reliable indication of pressure.

[XRe]

I don't mean to be picky here, but this seems like an extremely arbitrary metric.

Yes and no. Trying to judge pressure by the way a primer looks is generally not a superb idea, but its all most of us have. Some things that look like pressure signs can be caused by other things in the configuration. A short firing pin can allow the primer to bulge into the firing pin tunnel, and possibly get sheared off - this can also look like the cratering that occurs in an over-pressure situation.

The real problem is that, by the time you see pressure signs in the primer, you're already in a high pressure situation...

There are so many variables at work, how can anyone possible know that this is dangerous, without actually properly measuring the case pressures? (Don't get me wrong, it is probably a good canary in a underground mine, but it isn't really telling us much else that 'maybe' the pressure is getting high.)

In this case, he's got three distinct signs, and two "known not-so-good" loading parameters - he's got flattened, smeared, cratered primers, and he's loading WST with lead bullets to a short OAL. Its just a matter of time before something blows up.

What is the primary failure mode of overpressure (not signs, but failures)? When and where does it occur?

The only pressure related failures I've personally seen were in .40 w/ 180gr jacketed bullets - using WST. In both cases, they suffered a case rupture, which caused a "speed unload", blowing off the basepad, and blowing the mag contents out the bottom of the gun. Those represent situations where the pressure changed in a small way and exceeded what the base of the case could handle.

A second potential failure due to overpressure is far more catastrophic - severe setback or a double charge will cause a detonation, blowing chunks out of the gun and potentially injuring someone (possibly severely).

If the primary failure mode is primer related (rupture, blow out, blow by, whatever)

These things usually don't happen in pistol loads - although I have seen loads at high enough pressure that primers literally drop out of their cases after firing...

then has anyone ever tested and recorded primer appearance, starting at nominal pressures and building to failure? Have they done it for each BRAND and HARDNESS or primers? How do we know that flattening and cratering is the sign of imminent failure? Do all primers fail at similar pressures? If so, they certainly don't all look the same, since some are harder than others.

Based on info in load manuals, some small amount of true testing, and various anecdotal reports, we know that we can't trust primers to tell us much. In general, Federals will tend to flatten out quicker than others, and CCIs are super hard. But, we can take educated guesses based on what we see. If a Federal looks like it was melted and poured into the case head... bad news. If a Winchester shows severe flattening... also not good. Smearing suggests early unlocking of the gun (which can be caused by overly high pressure cycling the gun more quickly than the firing pin can be retracted, but is not the only way). Flattening could be exccessive headspace, but could also be too much pressure. Cratering could be a hot load in a gun with a short firing pin, or could be a pressure problem.

Seeing just one of those, maybe not something to panic about - three of 'em, though... you should consider what's going on.

Sure, different primers have different effects, but I doubt his intent was that it would lower the pressure to a 'safe' level.

Nope, sure won't change the pressure. The difference is that, if you're going to run higher pressure loads (and race gun loads are generally pretty high pressure), you probably want a primer designed to handle it.

A solid .40 load may flatten the shoulders on a Federal small pistol primer, but it shouldn't be extreme. My N320 loads (185gr Precision, 4.7gr N320, 1.185" OAL) flatten the corners on Federal, and leave WSPs looking nice and round. Those loads are probably ok... If they were flattening WSPs, and smooshing up Federals... I'd get concerned.

[XRe]

They had loads that were very over pressure where the primers looked fine (45000+ 40s) and safe loads where the primers flowed big time.

In part, this is due to the pressure curve of the load. High initial build up of pressure will flatten it more than a more gradual pressure curve. Headspace in their pressure gun may also play a factor.

[Joe4d]

By the time you get physical signs of pressure you are probably way over. And unlike many have stated primer flattening is not all we have. A chronograph which any reloader should have or have access , especially a reloader trying to extrapolate data outside of published ranges. Velocities that suddenly stop increasing linearly with the next grain increment are a much more reliable gauge that something is amiss than looking at primers.

[XRe]

Velocities that suddenly stop increasing linearly with the next grain increment are a much more reliable gauge that something is amiss than looking at primers.

When working up loads, and tracking the differences in velocity vs. change in load, this is useful. When loading up one particular load, shooting it, and then trying to guess whether you have a pressure problem or not, a chrono is even more worthless than trying to read primers.

ETA - note what Joe says about "linearly" - the implications are that the velocities could take a huge jump up, stop increasing entirely, or even go down! Different load combinations may do different things, but all are suspicious. Be careful not to confuse yourself, though - if you load one day, shoot, then load some more that are different by a tenth, and shoot, you may not see reliable results due to other factors. Load a ladder in one sitting and try to compare them all at once (unless, of course, you see signs that you should stop).

And, one other thing - just because a load is in a book does not even make it safe in your gun. Thus the advice in every load book out there to start small and move up. The reverse implication is that a load that isn't in the book is not necessarily unsafe - but you need to be careful about working it up, in the end...

Edited October 26, 2008 by XRe

[High Lord Gomer]

I finally got a chance to chrono those same loads (3.9 WST, 200 gr LTC, 1.155 OAL) and they were a very consistent 830 fps. I picked up some WSP primers and will try thoese next.

Thanks, everyone!

[Dave C]

I finally got a chance to chrono those same loads (3.9 WST, 200 gr LTC, 1.155 OAL) and they were a very consistent 830 fps. I picked up some WSP primers and will try thoese next.

Thanks, everyone!

The Winchester primers should work alot better.

I have been using WSPs/200 grain lead bullets on top of 3.8 grains of WST (1.135 OAL) ever since the PF dropped to 165.

It's a great 40 caliber load.

[ryan45kim]

XRe seams to know more about this then I do (that was a complement I’m not being smart) all I’m saying is that primers are not a true sign of pressure. They are one thing to look at just don’t say my primers look good so this is a safe load.

[DonT]

Ok, this has been a head-scratcher for me.

Casings on the left are my major load fired from STI

Win 180gr JHP

1.160oal

Fed 100 primer

4.7gr Titegroup

172.9pf

Casings on the right are my minor load fired from Beretta

Win 180gr JHP

1.125oal

Fed 100 primer

3.3gr Titegroup

130.7pf

Also getting flakes off unburnt powder on my arms from the minor load...Probably not a good powder choice for minor w/180's

[HSMITH]

Don, the raised edges on the minor brass is a Beretta thing, they all do it. The firing pin hole at the breechface is WAY too big. When you get into a high pressure situation it will start shaving brass into the firing pin hole, the primers will show a bright spot where it shears. Avoid shearing and it will be fine.

[DonT]

Thanks Howard, never realized that about Beretta.