I have been reading all of the interesting dialog pertaining to pressure and pressure signs. Very entertaining to say the least.

Without ruffling to many feathers I have a few questions for you guys on pressure and pressure signs.

I for one like to bring all of my rifles up to what I would call "Hot" or "Over Max". Once I find "it" I know were not to tread.

There are the subtle signs of high pressure like CHE, PRE, loose primer pockets and velocity. Then there are the not so subtle signs of high pressure like sticky bolt, extractor marks, shiny spots on the case head, blown primers etc.

Can these signs be put into perspective as it relates to PSI? For example, what do you think the psi of a 30-06 round with a sticky bolt lift would be? Or a 300 Win Mag with extractor marks? Or any round that has loose primer pockets after 3-4 firings etc.?

My WAG at this question is 80,000+ psi for your "subtle" pressure signs like loose primer pockets after several firings. When you get these signs, you don't just back off until they go away, you back off at least 5% of your load, which is typically several grains or MORE in a rifle cartridge. SAAMI specs that your rifle is designed to handle is at most 65,000 psi; the pressure limit for the latest cartridge designs like the various RUM's and WSM's.

Steve,

If your bolt is sticky, you've gone way too far. This is the problem with so many of the pressure indicators that you list. However, that having been said, I am NOT saying don't use them.

Hot Core will tell you that I am an idiot, but PRE and CHE are just not good indicators of pressure either. Why? First, it is depended upon comparing brass from a "standard" load with your load in a different lot of brass (if not manufacturer.) If you use the same brass you use for a "yard stick," then you have the issue of work hardened brass by virtue of reloading it. 2. Assuming that it does work, you are limiting your reloads to a yard stick that is a relatively narrow sample of ammo for you rifle. PMC ammo is really hot. Remington and Winchester are relatively "slow."

I suggest that you get several good reloading manuals preferably with pressures given in them and a chronograph. Again, his nibs will say I am crazy, but take my word for it, pressure is what drives the little bullet and more pressure drives it faster. TNSTAAFL; therefore, if you are getting velocities in excess of an average of book values, you are over the factory pressure limit. That being said (and HC makes much of this), the fact that your velocity is under the book value does NOT mean you are safe-and I agree with that statement whole heartedly. That is the reason you look at all all the other things. And READ the books, all of them.

Unless you are fortunate enough to be HC or have a Oehler Model 43, the only way you can be reasonably certain you are safe is to work slow, be methodical, and keep good notes. Know what you are doing. I mean that in the sense of understanding the process when you make a change.

For example, a flattened primer might appear on an initial loading with new cases with a light charge because when the firing pin hits the primer, it drives the case forward until the shoulder hits the chamber wall. Then when the primer fires, the initial pressure blows the primer out of its pocket, and when the powder ignites and you get full recoil, the case moves back against the bolt and crushes the primer. You observe a flattened primer, but it is because of pressure with a starting load. Probably not. Response: Play it again, Sam. Now the brass has stretched to full size. Shoot the same load in it, and you should not get flattened primers.

Remember that every time you change a component, you must make an adjustment down (ususally.) With medium to large capacity rifles you can move up a grain (assuming this isn't your really first load with the rifle-if so, try .5gr adjustments) at a time until you get about half way thru suggested loads, then cut back to .5 grain increases. First sign of pressure or if you reach factory max, STOP! And cut back .5gr or 1gr if you will be using the load in very hot weather or require very reliable ammo. With small capacity rifle, I'd suggest .5gr adjustments followed by .2gr adjustments. With large pistols, .5 or .3 followed by .2gr adjustments. Small pistol, cut that to .25gr and .1 gr adjustments.

Read about the cartridge you are reloading. Compare data. There are cartridges which are loaded low and those loaded hot. If you are shooting a modern firearm and the brass is up to it, you can get more from some of these oldies. The 30-06 and 9.3x62 are two of these; however, don't try to make a 30-06 into a 300WinMag or a 9.3x62 into a 9.3x64. There is no percentage in it. But you can obtain an extra 100fps with either of these cartridges and stay within safe pressure levels of modern rifles and brass.

If you can get five reloads from a magnum and eight from a standard you are probably OK on pressure. You can check this by starting with 10 cases and use them for three tests, and section one. Check for thinning of the case ahead of the web. After another two test, section another, and if no signs are there, test two more loads. At this point you are at seven loadings. If it looks good at this point, you have a load.

This bears repeating: There is no one test, no one indicator which will give you an A-OK on pressure. I'd be looking at all the things you mention even if I had an Oehler Mod 43. It provides just one more set of data to consider. In the end, it is your experience and your sense of things upon which you must depend.

Over time you will develop a sixth sense about a rifle. You will get to know if it is "fast" or it is "slow." You will know which bullets increase pressure and which don't increase pressure when you substitute them. You will begin to know which powders are linear and which are geometric in their pressure curves. This will tell you whether you must go up .1gr at a time, or you can go up .2gr at a time.

But until you have done it a while, go slow, get as much info as you can before you start, then make a sensible plan and follow it. Understand what you are doing and only do one thing (involve one change) at a time. Kudude

PS: Take anything that HC says about PRE or CHE with a grain of salt.

Steve4102

Let me give you a perfect example of how a load that gives absolutely no sign of pressure via CHE, PRE, flatened primers or hard bolt lift can be over pressure. Today I got around to testing some 30-06 loads; 3 factory and my favorite elk hunting load. The rifle is a new M70 Classic Sporter I picked up just befor Christmas. Haven't had a chance since then to wring it out so last night I mounted a strain guage for the M43 Oehler. Today I went to the range and set it up.

The first load tested out of the M70 was some Winchester 150 gr Silver Tip factory ammo that I have. Ten shots averaged 2840 fps, 55 ES, 23 SD with the average peak pressure (M43) being 53,300 psi with an ES of 4600 psi. That is about right for factory '06.

Next load was some Federal 150 gr FMJ. Velocity average 2914 fps for the 10 shot string with an ES of 43, SD of 16 and an average peak pressure of 53,600 psi with an ES of 4,300 psi. Again, just about right for the '06.

Third factory load was some LC67 M72 Match. Average velocity for the 10 shot string was 2601 fps, ES of 51, SD of 20 and an average peak prssure of 55,500 psi and an ES of 2,700 psi. Higher than the commercial factory but still under the SAAMI max average pressure.

Now for the information on my handload; DO NOT USE THIS LOAD! I will tell you what the load is; W-W cases once fired and neck sized, WLR primers, Hornady 190 gr SPBT, 61.5 gr of H4831SC. I worked this load up 4 years ago (I've killed 2 elk with it and several coyotes). It is a compressed load and the bullet is crimped in with a Lee factory crimp die. Accuracy out of the 24" barreled Huskvarna M98, which I developed the load in, is right at 1 MOA and velocity is 2740 fps. I knew that was getting up there, the chronograph said so, but there were no pressure signs and the load was accurate, I've not lost a case to enlarged primer pockets and it does kill elk.

In the M70 today (I only fired a 5 shot string for obvious reasons) that loads velocity averaged 2716 fps, ES of 26, SD of 11 and an average peak pressure of 65,300 psi with an ES of 1,400 psi. Accuracy was right at 1 MOA but YIKES! LOOK AT THAT PRESSURE!!!! "twas because it was developed in one rifle and used in another you say! Well I just happened to have the M98 Huskvarna there today also. I only fired 2 shots out of it because the peak pressure was 66,400 psi! Velocity was 2732 fps, Yikes again!!!

What can I say....there I was going along fat, dumb and happy with a load giving good velocity and apparently no pressure......little did I know! So there is a humbling tale of how the chronograph was telling me I was up there but since there was no CHE, excessive PRE or any other classic signs of pressure I just did not pay attention to the chronograph. I was looking for 2650 fps when I developed the load but like I said; no pressure signs so I went higher. Max effective range of the excuse is ZERO meters! The high pressure was indeed there and it excedes the SAAMI max by a bit. I was dman near into "proof load" range! Yikes again!

Excuse me, I have some bullets to pull.

Larry Gibson

Thanks kudude, good advice to be sure. But I have several manuals and a chrony. I pour over all kinds of data and work up loads very carefully looking for signs of pressure along the way. All of the signs you mentioned.
What I would like to know is how these pressure signs relate to psi? What is the approximate psi of an extractor mark or psi of a slightly sticky bolt. Things that you know are high pressure, what is the psi?

Larry, your 30-06 load brings up a good point. SAAMI has the 30-06 listed at 60,000psi and it's little brother the 270 Win at 65,000psi. It is my understanding that this discrepancy has to do with the rifles themselves, some older weaker 30-06 rifles can't handle the higher pressure. If this is the case then what is wrong with bringing a modern (M70) rifle chambered in 30-06 up to modern rifle pressures (65,000)? Your 30-06 load shows no signs of high pressure at 65,000psi, and why should it? There is a whole list of cartridges running at 65,000psi, why should your 30-06 be any different?

As kudude said " There are cartridges which are loaded low and those loaded hot. If you are shooting a modern firearm and the brass is up to it, you can get more from some of these oldies. The 30-06 and 9.3x62 are two of these; you can obtain an extra 100fps with either of these cartridges and stay within safe pressure levels of modern rifles and brass."

CMcDermott, Thanks for your reply. That's what I'm looking for. I do think you may be a bit high though, and I will tell you why. A few months ago I contacted John at Ramshot and asked if he had any data for the 30-06AI and Hunter. His reply for 180gr bullet was 62gr max at 2950fps in a 24 inch barrel. I worked up to 62gr without any signs of high pressure. I took it one step further to 62.5gr and "bingo" stiff bolt lift. It's just a guess on my part, but if his max was running at about 65,000psi then I don't know if a .5gr increase would cause pressure to rise all the way to 80,000psi.

Thanks everyone.

Any of the "pressure signs" are telling you that the brass is yeilding. It dosen't measure pressure, it says Back Off.
Good Luck!

quote:

If this is the case then what is wrong with bringing a modern (M70) rifle chambered in 30-06 up to modern rifle pressures (65,000)? Your 30-06 load shows no signs of high pressure at 65,000psi, and why should it? There is a whole list of cartridges running at 65,000psi, why should your 30-06 be any different?

The pressures Larry recorded with the M43 are, as I take it, "unadjusted" readings. The factory ammo likely was not in the low 50K but a bit higher, maybe another 5-10k or so. We just don`t know. We do know however the 65K he recorded with his load was 15K more then factory. That is border line 65K psi for the 270 if the m43 read right and a possible 75 K if the unit is reading low.
Either way I`d agree with him and back down. The M43 is giving a good look at the pressures of all the loads and the relationship of each to the other. 15K is about a 25% increase in psi over a factory rd, and call me sissy, I`d not care to feed my rifle a steady diet of it.

quote:

Originally posted by steve4102:
...kudude, good advice to be sure.

quote:

...What I would like to know is how these pressure signs relate to psi? What is the approximate psi of an extractor mark or psi of a slightly sticky bolt. Things that you know are high pressure, what is the psi?...

Hey Steve, Time for you to take the kudude prescribed Salt Pill, if you read my post any farther.

Hawkins short response is a good one.

There is no way to accurately answer your question, because the Case Hardness, Ductility, Flexability, whatever anyone wants to use to describe it - varies from Lot-to-Lot. So, the "psi" is not nearly as important as knowing how the actual Cases are responding to the Pressure.

Which brings us back to Hawkins post. Whatever "Methods" you can find to see first-hand the Effects of the Pressure on the Cases, is obviously the best.

I can think of two Methods that measure those effects first-hand - good old, time proven, never fail, relatively inexpensive, works on pistols, revolvers and ALL rifles which use a Case - CHE & PRE. Neither will tell you what the "PSI" is, but it will tell you when the Case is yeilding - just as Hawkins said.

Best of luck to you.

quote:

Originally posted by Ol` Joe:



Either way I`d agree with him and back down. The M43 is giving a good look at the pressures of all the loads and the relationship of each to the other. 15K is about a 25% increase in psi over a factory rd, and call me sissy, I`d not care to feed my rifle a steady diet of it.

I agree. My point was that at 65,000psi there should be no signs of "High" pressure in a 30-06. I didn't mean to imply that he should not back down a bit. Only that for pressure signs to rear their ugly head in a 30-06 case the pressure should be at or above 65,000psi not 60,000 as SAAMI has the 30-06 listed.

Hot Core and Hawkins, I agree that these signs of pressure are telling me that the case is "yielding" and I must back down. As I stated in my original post. Once I find it I don't go back. I was hoping that someone with a lot more experience than I could come up with a relationship between high pressure signs and PSI.

What got me going on this was comments by members here and other forums. Comments like "If you have reached sticky bolt lift you are over pressure, WAY over." OK, how far is "WAY" over, 5,000, 10,000, 30,000psi?

Steve I`ve "read" pressure signs normally start showing at 70K+ for most hunting cartridges. The signs don`t start with one specific part of the cartridge (primer, extractor mark, ect) but at random. I don`t know if this is true but I have seen it in print more then once and it is offered up at 24hourcampfire.com at times by gun writers there.
At any rate it is like running an engine at red line. Do the valves float, temp rise, or does smoke come out of it 1st? What speed does it happen at? Too far is too far. IMO if you can stop before it happens all the better.

Steve,

Because specs vary for different cartridges, how much you are over spec when the bolt sticks varies. That point (sticky bolt) will be constant within the specs of the brass; however, you begin to get "polishing" of the head at about 65,000 and sticky at 70,000 and stuck is "uh, oh!" pressure. This isn't science, Steve, its art. Kudude

PS: No one has commented on what causes these signs, but "polishing" occurs when the case is stuck in the chamber and bolt rotates against it. Sticky occurs when the brass flows into the ejector hole and forms a block to lefting the bolt. Stuck is when it has flowed a lot and is stuck every where. k-d

quote:

Originally posted by steve4102:
Larry, your 30-06 load brings up a good point. SAAMI has the 30-06 listed at 60,000psi and it's little brother the 270 Win at 65,000psi. It is my understanding that this discrepancy has to do with the rifles themselves, some older weaker 30-06 rifles can't handle the higher pressure. If this is the case then what is wrong with bringing a modern (M70) rifle chambered in 30-06 up to modern rifle pressures (65,000)? Your 30-06 load shows no signs of high pressure at 65,000psi, and why should it? There is a whole list of cartridges running at 65,000psi, why should your 30-06 be any different?

Thanks everyone.

Steve4102

You must remember that SAAMI's pressure operating limits (doesn't mean the cartridge must attain that pressure) are obtained in barrels with very tight specifications of chamber and bore/groove dimensions. Pressures obtained in those barrels are higher than what is obtained with production chambers and barrels. I pushed the SAAMI pressure in the M70 and exceded SAAMI's pressure in the M98. What do you do you think that load would actually be doing in a SAAMI test barrel? I'd bet both were well up into the 70,000 + psi range of "proof loads".

I don't know about you but I'm well past my days of shooting a steady diet of "proof loads" through my rifles. I've blown enough primers and helped destroy one action, that's enough for me. I'll back off to 2650 fps, the elk won't know the difference. However I'll feel a safer about it.

Larry Gibson

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by steve4102:
Larry, your 30-06 load brings up a good point. SAAMI has the 30-06 listed at 60,000psi and it's little brother the 270 Win at 65,000psi. It is my understanding that this discrepancy has to do with the rifles themselves, some older weaker 30-06 rifles can't handle the higher pressure. If this is the case then what is wrong with bringing a modern (M70) rifle chambered in 30-06 up to modern rifle pressures (65,000)? Your 30-06 load shows no signs of high pressure at 65,000psi, and why should it? There is a whole list of cartridges running at 65,000psi, why should your 30-06 be any different?

Thanks everyone.

Steve4102

You must remember that SAAMI's pressure operating limits (doesn't mean the cartridge must attain that pressure) are obtained in barrels with very tight specifications of chamber and bore/groove dimensions. Pressures obtained in those barrels are higher than what is obtained with production chambers and barrels. I pushed the SAAMI pressure in the M70 and exceded SAAMI's pressure in the M98. What do you do you think that load would actually be doing in a SAAMI test barrel? I'd bet both were well up into the 70,000 + psi range of "proof loads".

I don't know about you but I'm well past my days of shooting a steady diet of "proof loads" through my rifles. I've blown enough primers and helped destroy one action, that's enough for me. I'll back off to 2650 fps, the elk won't know the difference. However I'll feel a safer about it.

Larry Gibson

Larry, I'm going to give you the benefit of doubt in that you unwittingly created a
circular and contradictory arguement.

what a particular load does in a tighter SAAMI chamber SAAMI chamber is not specifically relevant.

what is relevant is what is safe in a particular chamber.

You aren't shooting "proof pressure loads" unless you are shooting them in that SAAMI chamber.

The SAAMI chamber is a loaders "worst case scenario" and SAAMI's worst case scenario ir irrelevant to most reloaders.
Frankly for the 30-06 I don't own either a low numbered springfield or an original 1895 winchester

Yes, in an ultra tight SAAMI chamber that specific load might be a proof pressure load
but in a looser chamber it won't be.

Looser production chambers and or thinner walled brass (more volume) mitigate potential problems.

Restricting the 30-06 in a modern sporting action to SAAMI pressure which ASSumes that the load MIGHT be chambered in an 1895 winchester or a low serial numbered '03 springfield
when in fact the only rifle someone owns
is a Rem700, a Win M70 etc... is defeating the purpose of not buying a case of Corelokts with the rifle and selling your loading press as scrap iron.


Loads developed to the "limit" whatever your own limits are MUST be done with awareness that the loads so developed must be fired ONLY in the particular rifle they were developed for and no other.

the argument that you are "hurting the rifle" let alone doing something more dangerous than producing starting level loads in bulk is plain and simple BS.

"Oh you are hurting the brass!" that's BS too
because I frankly don't expect to live another
80 years or so and that's what would be requied for me to burn up all the 30-06 brass I've already got...

If the brass is reuseable several times you aren't doing anything that is going to hurt a modern sporting rifle.

Would you load a 30-30 only to SAAMI max if you were going to be firing the cartridge in a Remington 788 bolt action chambered for the cartridge? (but then again if you are going to
"load it up" why not buy a 308 instead?)

I'll bet you can't find a T/C contender owner that so restricts themselves to SAAMI limits
when loading 30-30 loads for their contender
Infact I think you'll have an easier job finding someone who loads 30-30 ammo exclusively for a conender that only loads flat point bullets because some loading manual says they should... and if you want to conduct either search don't tell me as it would be too painful to watch (Like getting tied into an electric chair and given a choice of getting forced to watch re-runs of the Gary Shandling show or having someone throw the switch)

Frankly, I didn't buy an 1895 Marlin to shoot SAAMI level (trapdoor springfield) loads in it.
Nor did I buy a Remington 700 in 30-06 to shoot
308 level loads in it (I could've bought a 308 to do that)

I'm not sure I'd load a 30-06 that way if I were loading for a 98mauser of questionable heritage... or for that matter one with a pedigreed heritage.
I think the 98 mauser action to be a fine military action and it handles "worst case"
(ruptured case) events very well, but that doesn't mean it is the strongest action out there... not by a long-shot


"loading up" the 30-06 to 270win pressure levels in a Rem700/win70/Ruger77?

Anyone who insists this is "bad" is nuts.

AD

Allen,
The problem with your argument is that the factory doesn't have to make the 270 & 30-06 brass to be the same strength since the 30-06 is spec'ed to have a lower max pressure. Yes, with these particular two cartridges the only difference coming off the production line is PROBABLY the last die to form the necks and the die used to stamp the case designation. But go to the Chey-Tac website and look at what they say about forming 408 Chey-Tac cases from 505 Gibbs cases; the why of NOT doing it despite the OUTSIDE dimensions being very similar. Ask Remington about forming 6.8 SPC cases from 30 Rem cases, or making a Model 700 in 30 Remington and loading the cases to 65,000 psi. It's not just the rifle action, it is all of the pieces, including the brass cases that must be designed to have a 65000 psi limit. No action I know of fully supports the case heads, all of them have at least a small extractor cut, so there is only some thin brass containing that 65,000 psi of pressure. And that brass may be too thin by design, like a 30 Remington case that was supposed to max out at 42,000 CUP (not psi, and I can't find a conversion value for the 30 Remington). You need strong cases, and well as strong actions, for 65,000 psi to be safe.

quote:

Originally posted by Allan DeGroot:

You aren't shooting "proof pressure loads" unless you are shooting them in that SAAMI chamber.

AD

There is the problem with your train of thought. They don't "proof" SAAMI barrels by shooting "proof loads" in them. They test load developement with SAAMI barrels.

"Proof loads" are used to proof standard commercial rifles just like the M70. 65,000 average psi is above acceptable .270 average psi by the way. One shouldn't confuse the maximum allowable pressure with the average or mean allowable pressure. One should not also believe that all commercial ammunition is loaded to SAAMI's maximum allowable pressures. They are not. Also don't confuse current psi figures obtained with strain guage/transducers as they differ from those previously obtained by CUP. Many previous psi figures were simply conversions of CUP.

The M98 action is not "of questionable heritage". It is a commercial Huskvarna action.

Larry Gibson

quote:

Originally posted by CMcDermott:
Allen,
The problem with your argument is that the factory doesn't have to make the 270 & 30-06 brass to be the same strength since the 30-06 is spec'ed to have a lower max pressure. . You need strong cases, and well as strong actions, for 65,000 psi to be safe.

Hey CMcD, you are forgetting one important part of Larry's 30-06 load. That is, he did not see any visible or measurable signs of pressure with the load in question. If the 30-06 brass was not up to the task of 65,000psi then it would have showed up in the "yielding"(Hawkins term) of the brass.