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Pressure signs

As a safe reloader, I stop when I see the first pressure signs. Often, this is indicated by slightly flattened primers and noticeably stickier extraction. Usually, I get these indications before reaching the max load listing. This is in many different cartridges and many different rifles. So my question is...is there that big of a difference in rifles, where some rifles can fire loads over max with no pressure signs, while some others show pressure signs earlier? Do older rifles have a bit 'looser' fit, meaning they can handle high pressures? Just curious, with all the hoopla about super-velocity reloads flying about.

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Pressure signs

I personally don't think there is a significant difference between factory rifles of the same year but we are also dealing with the age of the rifle, make and model of rifle, and any unknown modifications that could have happened to that rifle if you are not the first owner. Surplus rifles in 30-06 for example, are going to react different than your rem 700 with a 30-06 load. Even in rifles made off the same assembly line could be different as the machining tools dull after repeated use. This is why we try to pound home the importance of starting safe and working up so the new reloader doesn't take some innocently placed info. and get hurt with it.

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Pressure signs

Just curious, with all the hoopla about super-velocity reloads flying about.

Nahhh they are showing signs, they are just ignoring them Wink

On a more serious note I have wondered if the newer short magnums will not show the pressure signs in the same way that a traditional cartridge would...

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Pressure signs

Kinda what I thought, bitmasher. I think you would still see the same kinds of pressure signs from the short mags.

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Pressure signs

What I've had the best luck with in loading the 300wsm is I look through 4 different manuals. I note the powder and load for the given bullet in each manual and start with the 3 powders that are recommended in each manual. Then I take an average of the maximun load recommendations of each powder, drop down 3grs and as long as I'm below the recommendation for that particular bullet That's where I start.

Yes, in some of the loads I was working up the pressure signs were showing up before I reached maximum recommendation. In most the average maximum were safe in my rifle. The 165gr Hornady Interbond started flattening primers at about 1gr. above the average maximum recommendation.

The type of bullet and the alloy it's constructed with can make a difference in the velocity the bullet travels down the barrel. When Remington was developing one of the rounds for their then new 300rum they went with the Nosler Partition instead of Swift version because they could get more velocity from the Partition. The Partition is a harder alloyed bullet and velocity sells.

Almost always if I'm going to load a round to hunt with I stay about a grain below the maximum. Temperature changes, altitude, or whatever else MAY effect the round and I don't want those problems in the field.

When it comes to velocity in most cases your only going to increase the trajectory by +1" at 300yds per 100fps and the energy by +or- 200ft/lbs at that same distance. When you start going beyond the maximum that the particlar rifle can maintain you start getting excessive wear and a shorter life span of the rifle. I've found if you need a little more push the best thing to do is get a bigger rifle.

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[ This Message was edited by: fuzzybear on 2004-04-05 14:13 ]

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Pressure signs

''When Remington was developing one of the rounds for their then new 300rum they went with the Nosler Partition instead of Swift version because they could get more velocity from the Partition. The Partition is a harder alloyed bullet and velocity sells.

That's an accurate statement. I like high velocity, but all the same, 2950 fps is all I need for hunting.

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you are smart to exercise smart reloading and shooting practice

 

Mister Venison – you are smart to exercise smart reloading and shooting practices.  Nothing is more important than safety.  Flattened primers and sticky extraction are danger signs as are backed out primers, and cracked cases and metal flow of primers back around the firing pin (aka pooling’ or deep pockets) and pierced primers.  You are wise to start very low on the reloading charts.  I generally start at the book minimum load and then work my way up in half grain increments until I find an accurate load. If I get to the maximum recommended load without excessive pressure signs and without a load performing with the accuracy that I am hoping for in my rifle, then I generally just change the projectile or powder (or both) and start at the bottom of the chart again working may way back up from the book minimum with that combination of powder and projectile.  There are infinite variables to play with in the quest for accuracy.  It is just not worth the risk to life and limb to play with loads above the recommended maximum powder charge – at least not in my opinion.  Heck – I’ll hunt with Damascus steel shotguns, but I won’t use unsafe loads in any gun!

 

ChesterGolf is right that even in rifles made off the same assembly line could be different.  I shoot a lot of military surplus rifles and find wide variety in even the same make and model.  This is why you usually can’t get away with just neck sizing cases fired in one rifle for re-use in another rifle.  You must generally full length size the cases back down to ‘standard’ specifications within the tolerances for any chamber designed for that cartridge.

 

I don’t have any experience with the newer short magnum cartridges but I would expect pressure signs to remain the same for any rifle and any cartridge.  Watch your primers for metal flow and your brass for fatigue not normally present.  Extra loud or substantially different recoil are danger signs too.  Basically anything that is outside the normal range is cause for concern.  Remember that your life and your sight LITERALLY depends on paying attention to these sorts of details.

 

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Slightly flattened primersw

Slightly flattened primersw are not necessarily a pressure sign. Sticky extraction is. Primers are not much value as a pressure sign. A crater around the dent in the primer can be caused by to large a fireing pin hole. A backed out primer is usually caused by to low pressure. Extreamly flat primer or a primer pocket shot loose is pressure. I don't pay a lot of attention to primers anymore. A shiny spot on the rim of the case equals pressure. That is the braqss flowing into the ejector hole. I like to measure case heads but I let them expand to SAMMI specs. That has never caused me a problem. Now if it hits over specs I can usually count on the primer pocket being loose, both tell me to back off. Watch your bolt face around the fireing pin hole. If you do have loose pockets and haven't caught it yet you'll see a circle etched around the fireing pin hole, flame cuttinf from gas escaping around the primer. Pressure causes that.

You may find a situation where you fire a round and the whole case is blackened with soot That is not high pressure, it is low pressure. What happens is there wasn't enough pressure to expand the case adequatly to seal the chamber. I see it in my cast loads a lot.

Older rifles might have a looser fit but then might be tighter also. What they should all be is in Sammi specs. If you are seeing a shiny ring around the case head, it is not necessarily pressure. Probably what you see then is the result of a case in a bit sloppy chamber that head spaces on a belt, as in a belted magnum, a rim, such as a 30-30, or an indication of a head space problem in a rimmed case. Those cases will seperate there soon but, it's not pressure doing it. That can be fixed with sizing dies adjustment in all the cases or in a case that headspaces on the shoulder, rimless, having a gunsmith adjust it out. Cheapest is to adjust it out with the sizing die.

If your rifle is a modern rifle, I doubt any max load will blow it up, they just don't let go that easy. Probably it won't harm your rifle at all unless you have a special cut minimun chamber with a tight throat. Or if you let your cases grow to long and the mouth starts into the lands and pinches the bullet, you will get a pressure jump but, it's not the charge, it's the case. Same can happen if you are seating the bullet to touch the lands, pressure will go up, just back out the bullet. 

If you measure your MTY cases and make sure all are under the trim length and make sure your bullets are seated back off the lands a bit you should have no trouble reaching max loads. One warning though. If you are using an older manual, most of them were produced without benifit of pressure testing equip. Those could be hot! I do have some old books and some of the max loads are simply not reachable in my firearms. doesn't mean they won't work in another nor does it mean they weren't over pressure when they were developed. That is why we start low and work our way up.

Now if you want a really unsafe situation, use a case thats to long, use a mag primer where a standard is called for and seat the bullet into the lands. You may not blow up the rifle but you'll very likely stick the bolt. A sticky bolt always indicates to me pressure but you can have to much pressure without a sticky bolt.

You can switch a mag primer for a standard primer and with ball powders I do. Just remember to reduce the load by a min of 5% and redevelope it. I like mag primers with ball powders because they are a bit harder to ignite, or so I've read. But I have used standard primers with ball powders and it's worked. Watch switching primers also. CCI's are fairly cool primers. Winchester and Federal are much hotter and just substituating a hot primer for a mild one can jump pressure.

There is no rocket science to this, most can be found in your reloading manual. All the companies are good about putting it in there. Where the problem comes in is that to many people suggest a way that is different and the one component change screws thing up. Now you can change things and after a while you'll figure out how to do it safely. But following the directions in the manuals always produces safe loads and the proceedure will help you find more than satisfactory loads for your rifle

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Nice reply Don, I agree with

Nice reply Don, I agree with that.

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Yep!

Yep! Nothing there that I will argue with either Don.  

That is a good point about the sticky bolt being a sign of unsafely high pressure too. 

Yes  

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Pressure

The only signs I ever noticed indicating excessive pressure were from a factory load of 125 grain 9x19mm +P rounds from Cor-Bon.  I fired them out of my two Browning Hi-Power pistols and not only were all the primers completely flattened after ejection, but the primer indentation strike had been forced back out flush with the rest of the primer and case head.  All you could see was a slightly discolored dot in the primer center where the firing pin had originally struck it, but no indentation remained after ejection.  Recoil was noticeably stiffer than normal, but both pistols handled that box of ammo just fine. Dancing

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