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How do you know when you are reaching overpressure?

This is a discussion on How do you know when you are reaching overpressure? within the Reloading forums, part of the Firearm Forum category; Some of you know that I recently managed to Kaboom my SBH... If you dont and you want the story, http://rugerforum.net/reloading/2174...hawk-down.html Anyway, now my question ...


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Old January 31st, 2017, 08:22 AM   #1
 
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How do you know when you are reaching overpressure?

Some of you know that I recently managed to Kaboom my SBH...

If you dont and you want the story, Blackhawk Down

Anyway, now my question is, how do you know when you are beginning to reach overpressure? I always see the reloading data say "these are max loadings, start 10% down and slowly work up". My question is, when you are slowly working your way up, how do you know when to stop? Certainly there must be a way to tell before kaboom....



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Old January 31st, 2017, 09:52 AM   #2
 
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Old January 31st, 2017, 11:08 AM   #3
 
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As you were told in the other thread, you did something DRASTICALLY wrong to blow the backstrap off a Blackhawk.

But to answer this question, well it's fairly simple to see the signs. Flattened primers, loosened primer pockets, hard extraction. All signs of over pressure.

That said, I have at time loaded up some REALLY hot stuff in some rounds testing various loads and had to beat cases out and the primer pockets were blown out after one firing. These rounds did zero damage to the pistol. These pistols are tested with "proof" loads that are extremely on the high pressure side. So again, a small mistake, or missing a charge a grain or so is not going to blow the backstrap off your pistol.

You seem to be adamant that you did nothing wrong and didn't overcharge it and it was just the load. For one, you have NO idea if you overcharged it or not, because that round is gone and no way to know for sure. Secondly, 10.5 grs of HP-38 under a 225gr JHP will deliver in the range of 38,000 Cup. HOT? yes. Blow the backstrap off? not even close.

May seem like I am harping here or picking on you, but from post one on the other thread you blamed it on the load that you got from Hodgdon and you haven't seemed to come off that thought. You have also admitted you are new to reloading. The point? Blaming your mishap on a manufacturer and not doubling down on your own process and making sure you are doing it right will get you hurt.

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Old January 31st, 2017, 11:14 AM   #4
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For my revolvers I watch for sticky extraction and measure case heads. For my semi-autos I inspect spent brass closely looking for anything out of the ordinary like breech imprinting, severely flattened/cratered/pierced primers, and I watch ejection patterns. One very good tool is my chronograph, while it doesn't show chamber pressures, it will tell me in my ammo is exhibiting extra high velocities. A couple articles on reading pressure signs; Reading Pressure Signs - MassReloading
Simple Trick for Monitoring Pressure of Your Rifle Reloads | Hodgdon Reloading
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Old January 31st, 2017, 11:49 AM   #5
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DirtyHarold, Assuming you have a US made gun where the manufacturer subscribes to SAAMI standards, the answer is quite simple. Ammo manufacturers and reloading manuals also subscribe to SAAMI standards and do not manufacture or publish loads that exceed those limits. Of course there are always a few exceptions .... one being for 45 Colt loads in Ruger or T/C guns where the guns are designed to handle much higher pressures. When these loads are listed, they always have a caveat .... "For Ruger and T/Cs Only". In other words, max loads in reloading manuals are no more powerful or more dangerous than factory ammo. Fact is, most factory ammo is loaded very close to SAAMI's max pressure because that's where you get optimum performance. Customers wouldn't buy ammo that didn't live up to its rated velocity and accuracy.

Reloading manuals such as Speer, Hornady, Sierra, Nosler, and others ... have their own SAAMI approved test labs and actually test each load to make sure it doesn't exceed SAAMI pressure standards. Further, these manuals always keep their max loads well below SAAMI pressure standards because they can't control what stupid people may do. There seems to be a trend with new reloaders where they think they have to run loads as hot as possible .... maybe even hotter than the manual's most powerful load. A sure way to get bad results.

So my recommendation is .... never exceed the loads listed in reputable reloading manuals and always use the same exact components as the manual lists. Further, use the recommended bullet seating depth (cartridge overall length). When you start swapping bullets or using different seating depths you can get yourself in a heap of trouble. As long as you stay within the limits in a reputable reloading manual, you will never have to worry about blowing up your gun. Now if you have an old gun or one that was foreign made by a lesser known company, all bets are off. That said, most newer foreign made brand name guns subscribe to CIP, which is the European equivalent to SAAMI.

All loads show signs of pressure so don't get yourself confused. As an example, a 38 Special is rated at a mere 17k psi chamber pressure. Standard primers start showing signs of over pressure at about 30k psi. So ...by the time you see excessive pressure signs in the primers, you are at about double the pressure limit.

Another sign people look for is hard extraction. What happens is the brass case and chamber both expand when a round is fired. The chamber will shrink back to its original shape but the brass stays expanded. This will cause hard extraction but it is not always a sign of over pressure. Further, you can have over pressure and still have easy spent case extraction. So ... these "signs" are merely an indication of pressure, not necessarily over pressure. It is quite common for factory ammo to display these "signs" when in fact they are not over pressure at all. Your best bet is to go by the book .... a good reloading manual!
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Old January 31st, 2017, 04:00 PM   #6
 
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Quote:
Originally Posted by Iowegan View Post
Your best bet is to go by the book .... a good reloading manual!
May I add a good current reloading manual. Back in the 1980s when I used to shoot IPSC the standard 45acp load to make major was 5.8 grains of WW231 for a 200 lead SWC. I notice now (on the Hodgon website) that 5.6 is the maximum. Memory fails me what the max load was back then but I'm pretty sure we weren't exceeding it. Who knows why the change...different formulas of gunpowder or more accurate ways of testing it...or both.
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Old January 31st, 2017, 04:20 PM   #7
 
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This is my experience with revolvers:
1. Sticky extraction. Pushing on the extractor takes a little effort, they don't just slide out.
2. Hard extraction. You have to tap the cases out with a rod and mallet.
3. Primer pockets start getting flattened. Look at factory fired cases to get an idea of what normal looking primers look like.
4. Primers fall out of the pocket . Pressure has enlarged the pockets...they are no longer useable. Back off that charge .

The biggest cause , and the most common , is an accidental double charge or a powder measure that drops a partial charge and the next case gets the overload.
These are the ones you have to be careful of....there are NO signs to look for except careful examination of every charged case before a bullet is seated.

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Old January 31st, 2017, 04:26 PM   #8
 
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HP38 is a very fast powder for a .44 Mag. Why were you going for max. with it? I have noticed punctured primers and sticky extraction with the .44 Mag. and
.357 Mag, both before the max. This is where I backed off. In both cases I was using powders slower burning than HP 38. 2400 in the .357 and Blue Dot in the .44. If not a bbl obstruction then an overload. You should have had other indicators before destruction of a Big Ruger.
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Old January 31st, 2017, 08:19 PM   #9
 
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I have been reloading since 1965. I shoot every week in good weather. I have been reloading for the .44 Mag (Ruger SBH, S&W 29, Ruger SRH) since 1967. I have never run faster powders at maximum magnum loads in any revolver. Usually, I run Hodgdon TiteGroup and other faster powders with midrange loads which will not blow the gun up, even double charged. I have never damaged a handgun. I normally do not load my own for semi autos.

With my normal heavy, hunting loads of Hodgdon H110, in my Ruger Super Redhawk, I run about a grain or a little more under SAAMI maximum. I lose maybe 60-70 fps but gain a pressure drop of a couple thousand PSI (safety headspace). The game which I may shoot, never knows the difference, plus, I have a little more cushion?

Whenever I change powders, primers or bullet makers, I always back off the recommended amount and work back up. I have read in a couple of articles, that monolithic pure copper bullets increase pressures? At least they do in my magnum rifles? For reloading, I use two scales, a digital and a Lyman 505, balance beam as my digital scale is not absolutely repeatable? Also, H110 powder throws from a powder measure very accurately.

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Old January 31st, 2017, 09:09 PM   #10
 
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Quote:
Originally Posted by SteveLV View Post
May I add a good current reloading manual. Back in the 1980s when I used to shoot IPSC the standard 45acp load to make major was 5.8 grains of WW231 for a 200 lead SWC. I notice now (on the Hodgon website) that 5.6 is the maximum. Memory fails me what the max load was back then but I'm pretty sure we weren't exceeding it. Who knows why the change...different formulas of gunpowder or more accurate ways of testing it...or both.
B.) More accurate testing methods. The 'old' method of chamber pressure testing involved a 'copper crusher' device, with a copper pellet that was measured after firing. That provided pressure info in copper units of pressure (CUP). The 'new' method is via piezoelectric transducers, which not only provide chamber pressure in PSI, but can provide a time/pressure graph of the shot.

Two other reasons for revised powder charge info over the years are: 1.) different test beds, either actual firearms or pressure barrels, between loading manual editions, and 2.) revisions by SAAMI for maximum chamber pressure.

Last edited by firescout; January 31st, 2017 at 09:12 PM. Reason: add info
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Old January 31st, 2017, 09:49 PM   #11
 
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I would not rely on flattened primers as different primers flatten at different rates and I have read numerous accounts of moderately over pressure ammo not showing any signs of flattened primers. I have scavenged 1000's of once fired Federal 38 spl shells (not marked +p) that have flattened primers. First I never shoot max loads (at 10% below). I also pay attention then extracting. Also as mentioned, just becasue a powder company gives you a loading does not mean it's a good load; best to use powders with burn rates relative to the ammo you are reloading. A SBH is one tough gun and even though your loading was max, it should not have been an issue. I'm thinking your case was either overcharged (from your description it sounds more like a mistake setting your scale) or an obstructed barrel. Glad you are okay. Never had a kaboom, but it is one of my worst nightmares..

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Old February 1st, 2017, 06:35 AM   #12
 
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>UPDATE: I also found that I had been using magnum primers, when you are only supposed to use the regular large pistol primers for HP-38. So it must have been a combination of longer length bullet due to being solid copper, and using a magnum primer.

If you used jacketed data for a monolithic bullet, you have your answer right there.
Monolithic bullets require their own loading data, and the charges are a lot less. The magnum primer probably had nothing to do with it--you may have simply used the wrong load data.
Monolithic and frangible bullets can not be loaded like standard bullets.
Attached is the Hodgdon list showing the monolithic and frangible bullets they have in their load data.

Pressure signs:
My favorite are:
1) Recoil in excess of a factory round with the same bullet weight
2) For semi-autos: case being thrown further or in a different direction that a factory round with the same bullet weight
3) Pressure ring comparison: above the extractor groove by about 1/8-1/4" you will find a pressure bulge (mostly where the web ends and there is a pressure concentrator (can't think of proper term). When I fire factory rounds, I find the pressure ring is pretty consistent. If I then load virgin cases of the same head stamp, I can measure the increase in the ring as the loads go up and I stop as soon as I get a pressure rind equal to the factory rounds. I may be stopping a bit premature, but that is fine.
For example, a .38 Spl may have a 0.379" diameter before firing. After firing a factory round, the pressure ring might be 0.3830". As I work up the load, I might get 0.3800", 0.3806", 0.3809", 0.3820", 0.3826", and 0.3829". In reality, I might be able to go up higher, but in reality, I have most likely already stopped as accuracy was going down and I have no need for max or near-max load.
4) Sudden change in primer appearance.

For a further writeup (though a lot has to do with bottleneck cases), I quote from:
https://www.shootersforum.com/handlo...ure-signs.html

on Pressure Signs by unclenick

Pressure Signs

Load manuals and experienced reloaders frequently advise working a load up in small charge increments while watching for pressure signs. Many beginners are unaware of all the signs, so, below is a partial list of pressure signs, along with alternate causes of the signs where I am aware of them. No one particular sign can be counted on to work in all guns nor even with any particular set of load components all the time. There is also no way to tell which sign will show up first in your gun and with your load combinations, so you have to learn to watch for them all.
1.Case bulging, particularly near an unsupported part of the head.
2.Case crack along side (may mean excess pressure, but may mean brittle, defective, draw mark scored, or worn out brass).
3.Case head expansion (CHE; may mean high pressure, may mean nothing in isolated case).
4.Case head separation (may mean high pressure, but may mean excess headspace or worn out brass).
5.Case splits in body in under 10 reloads-back loads down at least 2% (can also be due to ammonia vapor exposure or a brass defect in an individual case).
6.Case mouth split (may mean high pressure, but more often means case needed neck annealing).
7.Case pressure ring expansion (PRE; not much more reliable than case head expansion but may mean pressure is excessive).
8.Case primer pockets getting loose in five reloadings or fewer.
9.Case excessive stretching (this is actually visible pressure ring area stretching which may be due to excess pressure or to excess headspace).
10.Extractor marks appear on case head in semi-auto rifle after incrementing powder charge up (may be high pressure or bad timing or an extractor standing proud on the bolt face).
11.Fired case won’t fit back into chamber.
12.Gas leak (see Primer Leaking, below).
13.Groups start to open up at or beyond a suspected maximum load pressure.
14.Hard bolt lift.
15.Incipient case head separations (partial case head separation).
16.Incremental increase in powder charge results in lower velocity or at least in no increase in velocity (may also mean uneven bolt lug contact being forced to touch down on both sides; watch for stringing on the bolt lug axis as additional symptom of this). 17.Primer blown (primer falls out when gun is opened; same as loose primer pocket). 18.Primer cratering (may mean high pressure, or it may mean a worn firing pin or firing pin tunnel, or may mean you have a new production Remington bolt with chamfered firing pin tunnel).
19.Primer flattening (may mean high pressure, or may mean long headspace; some loads always make flat primers; softer primer cups (Federal) flatten more easily than harder ones (CCI), so it also can mean nothing at all).
20.Primer mushrooming (may mean high pressure, or may mean long headspace).
21.Primer piercing (may mean high pressure or may mean incorrect firing pin protrusion or incorrect firing pin nose shape).
22.Primer leaking around primer pocket (may mean high pressure, may mean loose primer pocket in case, may mean damaged primer was inserted, may mean primer backed out too far during firing, which excessive chamber headspace makes possible).
23.Short case life -back load off at least 2% (under 10 reloads in non-self-loaders or with military brass in self-loaders, 6 or less in self-loaders with commercial brass).
24.Sticky or hard case extraction (especially in revolvers this is a positive sign to knock the powder charge down at least 5%).
25.Torn case rim (from hard extraction).
26.Primer pocket expansion (PPE; this is likely no more accurate than CHE (3., above), but is a more sensitive measure for those with tools that can measure the inside diameter of a primer pocket repeatably to the nearest ten-thousandth of an inch).
27.Ejector and extractor impressions on the case head (can also be due to ejector and extractor fit problems).
28.Increase in required trimming frequency (this is a sudden increase in case length growth per load cycle; it can be caused by excess pressure, but can also be a sign of increasing head space due to some other problem. It is especially common as a pressure sign in lever action guns because the greater span from bolt face to rear lug allows more steel stretch when pressure gets excessive.) 29.Increasing apparent headspace (this means the cases are coming out longer, including from casehead to shoulder. It can mean bolt lug setback, which is usually an extreme pressure sign. It can also mean a loose barrel or an improperly set Savage barrel. Whatever the cause, the gun should go straight to the gunsmith for inspection.)
30.Gas or Flame Cutting of revolver top strap. (Can also be due to excessive barrel/cylinder gap that needs correction.)
31.Gas cutting of rifle bolt face by gas leaks around primer pocket. (Can also be result of occasional leaks from normal rounds firing, as is observed in many military gun bolts.)
32.Velocities at 15 ft higher than manual maximum load velocity for same powder and barrel length.
For example: one fellow using a .243 Win load one charge increment below the manual maximum got velocity 200 fps higher than the manual claimed for its maximum load's velocity. His single-shot action was popping open at every shot. With QuickLOAD we were able to calculate he had about 77,000 psi. An alternate explanation, if everything else is normal, is that your chronograph readings are incorrect. It is not uncommon to get high readings due to muzzle blast when the chronograph is too close to the gun. I recommend 15 feet minimum, since that is what the manual authors typically use. Some big magnum rifles need even more distance.
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Old February 1st, 2017, 09:57 AM   #13
 
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Quote:
Originally Posted by DirtyHarold View Post
Some of you know that I recently managed to Kaboom my SBH...

If you dont and you want the story, Blackhawk Down

Anyway, now my question is, how do you know when you are beginning to reach overpressure? I always see the reloading data say "these are max loadings, start 10% down and slowly work up". My question is, when you are slowly working your way up, how do you know when to stop? Certainly there must be a way to tell before kaboom....
If you go to Predatormastersforum.com, there is a great article called "understanding pressure ", Its in the reloading section. Its written in such a way that anyone can understand it, complete with pictures.

I know there are plenty of folks on here who think they know/actually know what they are talking about, but this is a good read.


Here Kitty Kitty
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Old February 1st, 2017, 10:19 AM   #14
 
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That's a good write up, but it is mostly applicable to bolt action rifles, not straight wall pistol cartridges, which are harder to read for pressure signs. ALL fairly hot magnum loads flatten primers to some extent, so that's never a sure sign. Split cases and case head separation is rare in revolvers but is usually weak brass, although it CAN be pressure. Bottom line, it is sometimes hard to read in revolvers, but the two most prominent are hard extraction and loosened primer pockets.

I disagree with an above statement about a load from a powder company maybe not being safe. If you use the brass, the primer, the powder and the bullet.........basically duplicating their load, you can be assured that is a safe load. It was tested in their test fixture and was well within SAAMI specs. If it gives you a problem, it's not the load, it's YOUR firearm

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Old February 2nd, 2017, 05:11 AM   #15
 
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It seems many are going to have a successful quest as searching for the Holy Grail. If you don't or can't have an understanding of the dynamics of detonation of a centerfire cartridge then I would advise take the advice of a professional and limit the internet smoke. Iowegan is that professional. His info will keep you safe.
No matter how many times the question is asked the physical facts remain the same. Somebody in a forum told me "this isn't rocket science" well, propellant, detonation and a missile launches I would contend it is. Destruction of a launch pad or your hand, caution should prevail.

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