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  #41  
Old 08-19-2011, 01:44 PM
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My formulation of the issue is a little different from some of the posts, but it leads to exactly the same conclusion.

Most rifles are built with very adequate safety margin. 99.99% of the time, you don't need all of it. The other .01% of the time, you need it very badly. If you have frivolously used it up for the sake of vanity, it won't be there when you need it.

In engineering terms, stress failures tend to follow a linear log S long N progression. That's the bafflespeak version of this: If you put the number of times a thing is stressed on the horizontal axis and the amount of stress applied on the vertical axis, you can then plot the number of stresses it takes to break the item. It's a straight line downward to the right. So any old 30-06 can launch a 200 grain bullet at 3200 FPS. And it can probably do it more than once. But metal failure climbs exponentially as stress is increased. I don't know the real numbers, but I suppose that at the top end, 20% more pressure causes 4X more rapid failure.

If you're not shooting a lot of rounds, odds are you'll never discover the upper limit of pressure.

It's your gun, your hands, and your eyes. Shoot as you please. As Woody Guthrie observed, some learn by reading, some learn by watching and some just have to pee on the electric fence.

A week from Wednesday, I have to shoot a couple of thousand 5.56 rounds at 150 F. That will generate very excessive pressure. But I'm going to do it from behind a steel door.
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  #42  
Old 01-04-2012, 01:42 PM
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Excellent indeed! But, I am surprised that no one seems to mention the ralationship of the area of the base of the cartridge...related to bolt thrust...related to chamber pressure?
Or the dufference how a relative straight wall case handles bolt thrust vs a tapered case.
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  #43  
Old 05-28-2012, 03:18 AM
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When I see a thread with multiple pages, I usually don't dive in, but this thread is amazing.

Thank You all for great info!


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  #44  
Old 01-11-2013, 07:01 AM
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This is such a questionalbe subject and it depends on who you talk to...All the signs MAY OR MAY NOT mean pressure problems...On ocassions I have had to work up loads in a wildcat caliber that no loading data is available, so one has to correlate with another caliber that is close in water capacity, caliber and whatever...Its not a comfortable situation at best, and must be approached with care..I have found however certain criteria that seems to show up with alarming consistency and that is sticky bolt uplift, indented case heads, and that little shiny ring on the case head..Primers vari so much that I have little faith in what they show, head expansion can really depend on the consistency of the brass, some brass is softer than others, and loose primer pockets seem to be a good case for backing off some grains.. A book of confusion can and has been written on the subject and believe me is a slippery slope..Its not something I enjoy these days..I like to take loads from the reloading books, and work with them a bit and you wont' get in trouble there, the books do leave room for law suit protection, but still I wouldn't suggest going over a grain or two past book max, and even do that with care..
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  #45  
Old 01-11-2013, 07:41 AM
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I was uncomfortable working up loads to pressure signs 10 years ago, but now when I make a new wildcat, like I did in October, I work up until short brass life, back off 4% powder change, and shot 4 deer. Business as usual.

The only thing different this year was that I worked up the loads in my vehicle.

Last edited by tnekkc; 01-11-2013 at 07:48 AM.
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  #46  
Old 01-11-2013, 09:57 AM
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  #47  
Old 01-26-2013, 03:32 PM
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I have wildcatted for years, less as I get older and "scareder".....

.Normally I have a pattern that I more or less follow and it goes about like this...

I look for the usual, flat primers, escaping gas around a primer, case head ejector marks, sticky bolts, but mostly I slow down when I see and ejector mark on the case head or a sticky bolt, thats when I normally back off...Keep in mind that its not an exact science and shrouded in BS and guess and by gosh and a book can be written on each of the above mentioned danger signs as each have pro and con, and they may or may not mean high pressure....then we have miking cases and I do that, but again all brass is different hardness so is that a real test of pressure. One positive is the chronograph and its a must in my opinion...and on and on...

I am presently working with a 9.5x62 a simple neck up from a 9.3x62 to a .375 bullet...no loading data available so one has to correlate with simulair rounds such as the 375 Scovill, 9.3x62 and the 375 Whalen and the 375 IMP Whalen and pray a prayer to the gun Gods and go fourth...I look for sticky bolts, extractor marks and chronograph, picking a powder like RL-15 in this case as it works well in the aforementioned correlation rounds...After each chronograph I reload the case and check for a loose primer pockets and sho nuff I found them and that was the only sign of pressure I found, so back to the drawing board cut back some more and now I have suitable loads for 300, 286 and 232 bullets in the 9.3x62, and I'm reasonably close to the starting loads of a 375 H&H, but it took a lot of work..This has worked best for me over the last 60 or so years..Its not foolproof but nothing, not even today sufisticated machinery is foolproof where pressure is concerned..

BTW, go slow and easy and remember you cannot be too carefull...

These problems are much simpler to deal with when you have Reloading manuals to start with..They take a lot of the guess work out of it...the book max loads are usually very close to max, at least within a couple of grains so the hard work is done...A beginning handloader would be smart to load his ammo at a gr. or two below book max until he becomes very comfortable with his ability..and beware again because with comfort in reloading, a certain amount of carelessness can also become comfortable, its the nature of the beast!!

So there you have my best offer, right or wrong..
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  #48  
Old 06-07-2013, 07:07 AM
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You didn't mention action exploding.
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  #49  
Old 07-26-2013, 05:53 AM
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I have a simple question that does not have a simple answer, but I will ask it anyway.

Lots of "pressure" signs posted on page one along with a good explanation as to their worth and their accuracy, so I will pick out only a few for my question.

Lets say I am working up a load in a modern bolt action rifle chambered in 223 Rem. The 223 has a MAP of 55K psi. For the sake of argument lets assume that the brass is not "soft" and the rifle is in perfect working condition.

At what psi would one start to see the "Obvious" pressure signs like stiff bolt lift, Or extractor marks, or blown primer, or loose primer pocket after one firing?

I know there is no absolute answer to this question, but there has to be some actual tested data to give us a ball park.

I would have to think that one would not see any of these pressure signs until pressures are above 65K as many cartridges run at this pressure. I read things all the time by handloaders saying "didn't see any pressure signs" in their 223/5.56 handloads. My question is, why would they? The pressure signs they are seeking will not magically appear as soon as they are over SAAMI max of 55K will they? The brass, the bolt and the rifle don't know when SAAMI says enough is enough.

So, at what pressures do these obvious signs of pressure actually appear(ball park please) and is this over pressure different for different cartridges just because SAAMI says so?
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  #50  
Old 07-26-2013, 07:55 AM
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MANY factors contribute. Don't _count_ on seeing 'pressure signs' until 75k psi or so.
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  #51  
Old 07-27-2013, 06:34 PM
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There is no obvious answer for three reasons:

1. The brass isn't calibrated. Different manufacturers use different alloys, so you have not only dimensional variables but metallurgical variables. One brand of case can get a loose primer pocket while another endures several times more reloading cycles at the same pressure before that happens. So a pressure sign in brass really only tells you for sure that the particular brand you have is at its limit, and not that the gun steel is experiencing excess pressure. Nonetheless, it is useful to know not to push that particular brass any harder, as brass failure can do serious damage to the gun. If cases appear about to fail after firing with your load, back the load down at least 5%. Also, if you full length resize, check your gun's headspace. Excess headspace can promote premature brass failure in a couple of modes in fully resized cases. Neck sized cases and cases with shoulders bumped back just a thousandth or two should not care much about headspace.

2. The primers aren't calibrated. Different primers have different cup thicknesses and some are nickel-plated, both of which give the cups different hardness which affects how much they deform under pressure. It's not at all uncommon for one primer to show pressure signs where a different brand does not. So a pressure sign based on primer appearance really only tells you for certain that your particular make of primer is at its limit, and not that the gun is. Nonetheless, it is useful to know not to push that particular primer any harder, as primer failure will badly score the face of your bolt and occasionally does other damage. If primers start failing with a particular load, back the load down 5%. Again, check your gun's headspace as excess headspace allows a primer cup to move further out of the primer pocket during firing. Tight headspace can help with degree of primer mushrooming, in particular.

3. The gun isn't calibrated. Different guns constrain the cartridge with different effectiveness. A light weight rifle constrains it less rigidly than a heavy benchrest rifle does, so the pressure at which the steel starts to stretch enough to allow sticky bolt lift can vary significantly. If you get sticky bolt lift in a light rifle, the same load may well show no problem at all in a heavier one. Nonetheless it is useful to know you should back that load down 5% in your particular gun to keep from fatiguing the steel.

I think MZ5's number is not unreasonable as a ballparkish number for sticky bolt lift on many rifles using some well liked components, but you will have loose primer pockets long before you get there if you use Federal brass, which is soft. It's famous for delivering loose primer pockets (primer falls out when you eject the case) on the first firing of their own normal pressure factory loads in the magnum calibers. That's a strong indication their own loads are overpressure for their own brass, and that's still within SAAMI standard. It will get develop sticky bolt lift sooner, too.

The .223 is often chambered in receivers normally used for .308 sized cartridges, so its about 25% narrower and so metal will be correspondingly heavier. In that design you can expect corresponding additional resistance to stretching enough to let sticky bolt lift occur.

There's just no hard number to be had.
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Last edited by unclenick; 07-30-2013 at 07:41 AM. Reason: typo fix
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  #52  
Old 07-28-2013, 05:12 AM
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Originally Posted by MZ5 View Post
MANY factors contribute. Don't _count_ on seeing 'pressure signs' until 75k psi or so.
So, 75K is a ball park number for seeing high pressure signs, thanks.

This brings me to the other part of my question, Is this "ball park" psi approximately the same for most modern cartridges in modern actions? For example the 7.62 x 39 has a MAP of 45K psi, assuming the 7.62 x 39 brass is not soft (Federal) is it safe to say that these "pressure signs" will not magically appear at 46K or 50K or even 60K and if they do appear the load could be as much as 30K over pressure? Same for the 223 as well, it has a MAP of 55K psi, is it safe to say that these pressure signs we are taught to look for will not show up until we are almost 20K over pressure?
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  #53  
Old 07-28-2013, 07:19 AM
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Steve - Please read Unclenicks post again. THERE IS NO ABSOLUTE OR STANDARD HIGH PRESSURE WARNING INDICATORS!.

Too many variables that are dependent on all sorts of parameters. Let's just say if there is "sticky" bolt lift, flattened appearing primers, extractor/ejector marks on case base, cratered primer firing pin indentations, swelled case base and, at times, case appearance, you should be backing down on the charges.

The only way you are going to know with confidence about chamber pressures is when you use current pressure reading equipment.
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  #54  
Old 07-28-2013, 07:30 AM
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The only way you are going to know with confidence about chamber pressures is when you use current pressure reading equipment.
My point exactly. Someone, somewhere someplace with pressure testing equipment has to have tested for these so called pressure signs and when they "Might" appear. Otherwise they would not be sign of over pressure.
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  #55  
Old 07-30-2013, 09:07 AM
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Quote:
Originally Posted by Steve4102
…somewhere someplace with pressure testing equipment has to have tested for these so called pressure signs…
No. Pressure signs were developed in lieu of pressure test equipment in a time when most experimenters, like P. O. Ackley and Ken Waters, and even some bullet makers, like Hornady and Speer, had no pressure test equipment (the reason a lot of their early load manuals had loads that later proved too hot in some guns). The signs work by deductive reasoning. To wit: if something shows signs of potentially destructive deformation, you can deduce you are running at a pressure too high for it withstand on a regular basis, whatever the heck that pressure might be.

For example, sticky bolt lift due to excess pressure is ultimately due to the same phenomenon that causes sticky case extraction in revolvers. That is, the pressure gets high enough to cause the steel to stretch beyond the 100% elastic limit of the brass. Steel has more elasticity than brass, so it can do this. When the excessively stretched steel springs back to size, the brass does not get 100% back to size with it, so the the steel winds up clamping down on the brass. This causes friction between the brass and the sides of the chamber and between the brass and the bolt face of a rifle. So, from sticky extraction or sticky bolt lift you can deduce the steel is stretching more than normal. That's bad for the fatigue life of the steel, and hence is too much pressure for the steel to contain reliably over many thousands of rounds without fatiguing. Thus you need to reduce the load. But that doesn't tell you how many psi were involved in reaching excess stretching. That depends on the dimensions and temper of the steel.


Again:

  • The cases aren't calibrated to deform at a particular psi.
  • The primers aren't calibrated to deform at a particular psi.
  • The gun isn't calibrated to stretch excessively at any particular SAAMI pressure.

It's individual. I think MZ5's number is probably not a bad guess for typical sporting weight rifles and chamberings, based on my own experience. But its just an estimated average. The average weight of an adult male human is about 180 lbs. That doesn't mean any randomly selected male can be sure to weigh 180 lbs. Same with the pressures at which sticky-anything occurs.
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  #56  
Old 08-27-2013, 03:09 PM
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Htshot,
Don't know about exploding actions, never had one, worst I have had is a sticky bolt and one or two primers pop out, thats exciting enough for me!!

Steve,
It has been my experience that the first signs sugnificant pressure will normally be a sticky bolt lift and/or a square extractor mark on your case head..and its time to back off a grain or two and get out the chronograph and see if your velocity is within the correct bounds. Again your flying by the seat of your pants. Problem is there is no other way unless you have a caliber that is listed in some load data somewhere. Therein lies the problem of wildcatting! And today there is little reason to wildcat as your simply reinventing a wheel for the most part.

You plenty safe just buying a couple of reloading books and using already developed loads and the reloading books have leftt themselves a safty buffer for sure.
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  #57  
Old 08-28-2013, 07:02 AM
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Originally Posted by Big 5 View Post
Steve,
It has been .................................... data somewhere. Therein lies the problem of wildcatting!
And today there is little reason to wildcat as your simply reinventing a wheel for the most part.

You plenty safe just buying a couple of reloading books and using already developed loads and the reloading books have leftt themselves a safty buffer for sure.
Big 5,
I will take mile exception to the sentiment quoted in the first two lines of text above. There Are Still Reasons to "WildCat".
Where do I find modern powder loading data for the .25 Stevens Short and Long cartridges?
Where do I find modern powder loading data for the .32 Long RF cartridge?
Where do I find ANY loading data on a .25ACP cartridge with a case length of 1.250 inches?
Or one with a case length of 1.125 inches?
Or one with a case length of 1.055 inches?
How about .32 Extra Long?
Or even the .32 Long Rifle?
Yes they are "Obsolete" by modern manufacturers decisions but there are still firearms chambered for them that the owners would like a chance to fire again, safely.

Do you deny Them that pleasure by declaring there is 'no need to wildcat any more'?

Which Loading Manual do you claim lists loading data for current Modern Smokeless Powders, or for that matter, actual tested loads for Black Powder with the Pressure testing data attached?
So far I have found none, but then I have only been looking for about 10 to 40 years off and on, not continuous searching.

Best Regards,
Chev. William
Owner fo some "Orphaned and Obsolete" chambered firearms.
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  #58  
Old 02-15-2014, 01:09 AM
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Originally Posted by unclenick View Post
I moved your post into the pressure sign thread to avoid confusion. I didn't realize it was closed. Not meant to be. I've invited input.

My general point in listing pressure signs I've run into is they can mean something else. I'll add your comment to the exceptions in the list for #21, which 11 refers to, and also add that is most likely when headspace is excessive.

I'll keep trying to add any new ones or new alternative interpretations folks post to the list so a beginner can get the information in that one place.

I went to pick up a new .308 rifle one time whose bolt was blackened and a red ring of sealant deposited around the firing pin hole. Someone had decided to try it out and used some hot surplus load, no doubt. Being out of spec is one reason rounds get surplused out, so caveat emptor. But the headspace checked out OK, so it was definitely an ammo problem.
Hey Nick, you know what I'm up to, was working with the Barnes 175s and bumped into some problems (pressure). Saved examples to take pics... want me to post them? Almost everything from cratered primers to case head.

Last edited by rojkoh; 02-24-2014 at 04:15 PM.
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  #59  
Old 02-16-2014, 10:27 AM
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As an old dyed in the wool wildcatter, and I might add in my early days, before there was no info to be had most of us had a system that was pretty much accepted by all us curmudgeons inasmuch as we had no chronographs or rather couldn't afford one..

Start low and work up 1 gr. at a time and at some point go to half gr. increases, has always been a golden rule.

All the 33 suggestions in the earlier post by someone may or may not indicate pressure, and some of those relate to brass fatigue and/or brass that should have been annealed or tosse.

We would start with the safe mild loads and go until we noticed flat primers, or primer leaks, extractor indentions on the case head, or sticky bolt lift, and mic cases for excessive expansion. Some considered any expansion as pressure while others would go to .0005 as max expansion. Any expansion is pressure but I always gave .003 as my personal max. These were usually the order of things, but any one of them cropped up then it was a red flag and time for considering cutting back a grain, but thats a maybe time, so you proceed until something else happens, a crack as opposed to a boom is really tme to back off....

The problem is that any one if of the pressure signs in itself may or may not be an indications of pressure, but a couple of them together is WHOA TIME, and cut back time..Like I said its all we had to play with and it seemed to work for the careful handloader, the cowboys blew primers, stuck cases and blew cases in half, and on ocassion blew up a gun appparantly. Nobody I know ever blew up a gun, and those blown guns seem to be because someone forgot that it was bullseye in the powder measure..

Later the less expensive chronographs coupled with the above pressure signs, pretty much solved most of the problems and when all was applied to each other wildcatting became much easier and reached a point of not really needed anymore,. Al we do today is remake the wheel.

I very wildcat these days but did come up with a 9.5x62 (375x9.3x62) and absolutly no load data was available, so I "trans-copped a corelatable standard of comparison" ( I just made that up) and started with 9.3x62 loads figureing a probably 5% increase in powder and with the use of the chronograph and all the above pressure signs I found out it still worked and I got 2350 FPS with a 300 gr. Woodleigh, not to shabby for a case just slightly larger than a 30-06..I also found out that using 30-06 ( an acceptably practice in some circles) was a piss poor idea, and that Graff brass is PVV brass and as cheap as 30-06 brass..I also used 375 Whelan; 375 Whelen IMP load data; 375 Styr, 375 Ruger and some other wildcats to the extent that I studied their load data for a comparison.

Also I always shot each load and reloaded that case to know when primer pockets enlarged as thats a sho nuff indication of pressure and time to cut back a grain or two.

Thats the best you can expect to do with what we have to work with and as a matter of fact the real tech stuff the factorys have is "probably" not any more accurate as the above when we are working towards max loads...

There are so many varibles to deal with..for instance primers have different hardness and can sure be misleading, powders from batch to batch can be different, brass itself varis in thickness and makes and gives different water capacity, and on and on.

So when you reach max or think you have reached max, cut back 2 grs. and call it good! 50 or 75 FPS will never make any difference in anything.

Last step is to shoot that best load and reload it and shoot it again and again until it fails or at least until you get to 10 or 15 loads with only two trims and no brass failure. Then your pooping in tall cottom my man.
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Old 02-16-2014, 11:22 AM
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Originally Posted by Big 5 View Post
As an old dyed in the wool wildcatter, and I might add in my early days, before there was no info to be had most of us had a system that was pretty much accepted by all us curmudgeons inasmuch as we had no chronographs or rather couldn't afford one..

Start low and work up 1 gr. at a time and at some point go to half gr. increases, has always been a golden rule.

All the 33 suggestions in the earlier post by someone may or may not indicate pressure, and some of those relate to brass fatigue and/or brass that should have been annealed or tosse.

We would start with the safe mild loads and go until we noticed flat primers, or primer leaks, extractor indentions on the case head, or sticky bolt lift, and mic cases for excessive expansion. Some considered any expansion as pressure while others would go to .0005 as max expansion. Any expansion is pressure but I always gave .003 as my personal max. These were usually the order of things, but any one of them cropped up then it was a red flag and time for considering cutting back a grain, but thats a maybe time, so you proceed until something else happens, a crack as opposed to a boom is really tme to back off....

The problem is that any one if of the pressure signs in itself may or may not be an indications of pressure, but a couple of them together is WHOA TIME, and cut back time..Like I said its all we had to play with and it seemed to work for the careful handloader, the cowboys blew primers, stuck cases and blew cases in half, and on ocassion blew up a gun appparantly. Nobody I know ever blew up a gun, and those blown guns seem to be because someone forgot that it was bullseye in the powder measure..

Later the less expensive chronographs coupled with the above pressure signs, pretty much solved most of the problems and when all was applied to each other wildcatting became much easier and reached a point of not really needed anymore,. Al we do today is remake the wheel.

I very wildcat these days but did come up with a 9.5x62 (375x9.3x62) and absolutly no load data was available, so I "trans-copped a corelatable standard of comparison" ( I just made that up) and started with 9.3x62 loads figureing a probably 5% increase in powder and with the use of the chronograph and all the above pressure signs I found out it still worked and I got 2350 FPS with a 300 gr. Woodleigh, not to shabby for a case just slightly larger than a 30-06..I also found out that using 30-06 ( an acceptably practice in some circles) was a piss poor idea, and that Graff brass is PVV brass and as cheap as 30-06 brass..I also used 375 Whelan; 375 Whelen IMP load data; 375 Styr, 375 Ruger and some other wildcats to the extent that I studied their load data for a comparison.

Also I always shot each load and reloaded that case to know when primer pockets enlarged as thats a sho nuff indication of pressure and time to cut back a grain or two.

Thats the best you can expect to do with what we have to work with and as a matter of fact the real tech stuff the factorys have is "probably" not any more accurate as the above when we are working towards max loads...

There are so many varibles to deal with..for instance primers have different hardness and can sure be misleading, powders from batch to batch can be different, brass itself varis in thickness and makes and gives different water capacity, and on and on.

So when you reach max or think you have reached max, cut back 2 grs. and call it good! 50 or 75 FPS will never make any difference in anything.

Last step is to shoot that best load and reload it and shoot it again and again until it fails or at least until you get to 10 or 15 loads with only two trims and no brass failure. Then your pooping in tall cottom my man.
The old trick taught to me by Mid Tompkins and some of the CA team shooters is to increase in 2/10ths increments, because depending on the powder thrower you're using, 1/10th makes little difference. Because of the ammo testing I'm doing (.3087.62), I've gone to the Lyman Gen 6 electronic scale for more accurate readings, depending on the powder. Most powder throwers measure by Volume, not weight. The most accurate of the powder throwers (mechanical) is the Culver measure (currently made by Harrell and available from Sinclair). But with certain powders like 4064 and RL-15, you will get some inconsistencies because of the way the powder is made. That's why I went electronic.

I pressure check first, then work up in 2/10ths increments and then shoot it in 10 round groups. Yes, because of some of the nit pickers I am pushed pressure to the point of a case head sep. They just don't understand the differences in the various powders and pressure curves, especially in a gas gun.
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