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For decades, I defended the notion of miking cases to get an idea of the internal pressures being developed. I'm the editor who originally published both Bob Hagel's and Ken Waters' articles on how they do it. I also published Waters' "Pet Loads" article as a supplement for his Pet Loads book.
At the time, Waters and I both considered Hagel's method extremely risky. I still do (because it IS!). I supported Waters' more moderate approach. I've since learned how foolish and unreliable any variation of this basic technique is.

� Many cases don't expand enough, even at 80,000 lb/sq in., to warn of risky or excessive pressures.

� Catastrophic failures of overloaded rifles may occur with either the first over-hot round, or they may occur only after years of repeated use of over-hot loads. In the latter type of failure, the rifle has appeared "safe" with these loads, clear up until the time one round "caused" the failure "for no apparent reason."

� Cases work-harden in use. Repeated use makes them become brittle in the crucial portion exposed in the breech � typically 0.200 inch of the head of the case. Cases already too hard to show "excessive" expansion here (some, even at 80,000 lb/sq in.) are especially likely to become brittle in repeated firings and reloadings, and spew wild gas and bits of brass into a shooter's face. I have on hand now a rifle utterly demolished when half the head of the case blew back through the action. The rest of the case is still in the apparently unharmed barrel, but the receiver is in many pieces, and my friend still has one piece of brass in his face (a larger chunk was surgically removed).

� The maximum safe limit for many rifles and cartridges is well below the level of peak pressures that many cases can handle without any discernible or measurable indication of excess.

� The less experienced you are in the use of this method, the greater is the certainty that miking your cases will inevitably lead you to accept dangerously high pressures as "safe."

Careful lab tests of many typical "pet" loads, developed by attention to traditionally accepted "signs" of pressure, have shown their peak pressures to be 70,000 to 75,000 lb/sq in. The highest SAAMI "safe" pressure I know of, for any cartridge or rifle, is 65,000 lb/sq in. Most are lower. Many are much lower.

Some carefully lab-tested loads, developed by miking case rims, webs, and expansion rings, have developed 80,000 lb/sq in. without measurable expansion.

Stay well below the maximum charges listed in the manuals, and you'll be worlds safer without significant sacrifice in down-range performance. No micrometer is a reliable pressure gauge.

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I just did a bunch of the same research, and came to the same conclusions, by shooting loads worked up with "home" pressure testing methods (from bolt lift to measuring case heads) in a professional pressure lab. Could find no consistent correlation between case expansion (or even bolt lift!) and pressure. An article will appear in the next HANDLOADER on the experiments--which will also corroborate Blaine's contention that a chronograph is the best indicator of pressure.

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And being immensely privileged to be privy to a lot of factual findings -- both classic and recent -- about interior ballistics, factual material that hasn't found its way into the gun magazines and isn't obvious enough that every opiner in print or cyberspace sees its validity at first glance, I feel duty-bound to share the impact of these facts even though such sharing inspires onslaughts of doubts and dissenting opinions. It's worth noting, IMO, that none of these doubts or dissenting opinions comes from a dependable, well equipped experimenter who has tested and examined the validity of case expansion with good pressure-measuring equipment.

When several careful and dependable experimenters, each well equipped and confirming the others' findings, report that miking case expansion to "read" pressure has in their experience produced two significant bodies of serious error, I take all that as observed fact, not conjecture or opinion.

Those two bodies of repeatedly observed error are --
(a) case-expansion readings that indicate dangerously high pressures, when the pressure guns indicate pressures well below maximums
and
(b) case-expansion readings that DON'T indicate excessive pressures, when the pressure guns indicate pressures at AND ABOVE proof-load levels -- DANGEROUS loads that case-expansion readings do NOT detect, for example 70,000, 75,000, even 90,000 lb/sq in. in cartridges SAAMI-rated at safe only below 60,000 lb/sq in.

So my opinion of case expansion's worth doesn't matter. The facts do matter. And I don't have to have discovered those facts myself. Also, my acceptance of these facts isn't determined or affected by the dissenting opinions of otherwise well informed and intelligent people who happen NOT to have learned these same facts.

So my opinion is that the statement "Case expansion is a dangerously misleading and undependable method of trying to 'read' peak chamber pressures" is a well and repeatedly proven fact, based on well and repeatedly proven facts (not opinions based on old, opinion-based writings). I also opine with some confidence that this opinion is sturdily supported by enough repeatedly observed facts to qualify it as a final opinion.

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An old and less precise method ( case head expansion ) is used on "Wildcats" and non SAAMI cases. The measurement point is at the head adjacent to the rim or extractor groove but not the rim itself and NOT the point of normal bulge!!!. Testing should be made on once fired cases. The hardness of cartridges varies; a softer brass will deform at a lower pressure than a harder brass. For measurement a blade micrometer ( $135 ) accurate to 0.0001" is mandatory. The more common 0.001" will not give accuracy required.

New cases can give deceptive expansion readings. The first firing of any case will usually cause more deflection at the web than subsequent firings. We look at an expansion of 0.0003" with no individual reading over 0.0005". Case head expansion measuring 0.0003" to 0.0005" is generally accepted as representing pressures in the 50,000 CUP range *( thats CUP not PSI ).

Because copper alloys including brass work-harden, we use cases for only 3 ( thats three ) firings before retiring them from testing!!! Remember this method does not give absolute pressures. It is only a relative indicator and results can vary among rifle and cases.

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Originally posted by jackfish:

Or what does Speer (#13, page 55) actually say about case head expansion measurement?

[QUOTE]An old and less precise method ( case head expansion ) is used on "Wildcats" and non SAAMI cases. The measurement point is at the head adjacent to the rim or extractor groove but not the rim itself and NOT the point of normal bulge!!!. Testing should be made on once fired cases. The hardness of cartridges varies; a softer brass will deform at a lower pressure than a harder brass. For measurement a blade micrometer ( $135 ) accurate to 0.0001" is mandatory. The more common 0.001" will not give accuracy required.

New cases can give deceptive expansion readings. The first firing of any case will usually cause more deflection at the web than subsequent firings. We look at an expansion of 0.0003" with no individual reading over 0.0005". Case head expansion measuring 0.0003" to 0.0005" is generally accepted as representing pressures in the 50,000 CUP range *( thats CUP not PSI ).

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Originally posted by jackfish:
Careful lab tests of many typical "pet" loads, developed by attention to traditionally accepted "signs" of pressure, have shown their peak pressures to be 70,000 to 75,000 lb/sq in. The highest SAAMI "safe" pressure I know of, for any cartridge or rifle, is 65,000 lb/sq in. Most are lower. Many are much lower.

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Originally posted by jackfish:
?ah, yump, I just add powder till the bolt sticks, and then I back off .1grains? safe in my gun?

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I, on the other hand, use the reloading manuals, computer simulations, stop BEFORE either the books or the computer says I should, look at primers (if it aint round, it?s too high), measure case expansion, chronograph and compare my field results with book and computer expectations, and err to the side of caution.

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Originally posted by jackfish:
When pushed about his statements Ken Howell continued:

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And being immensely privileged to be privy to a lot of factual findings -- both classic and recent -- about interior ballistics, factual material that hasn't found its way into the gun magazines and isn't obvious enough that every opiner in print or cyberspace sees its validity at first glance, I feel duty-bound to share the impact of these facts even though such sharing inspires onslaughts of doubts and dissenting opinions. It's worth noting, IMO, that none of these doubts or dissenting opinions comes from a dependable, well equipped experimenter who has tested and examined the validity of case expansion with good pressure-measuring equipment.

When several careful and dependable experimenters, each well equipped and confirming the others' findings, report that miking case expansion to "read" pressure has in their experience produced two significant bodies of serious error, I take all that as observed fact, not conjecture or opinion.

Those two bodies of repeatedly observed error are --
(a) case-expansion readings that indicate dangerously high pressures, when the pressure guns indicate pressures well below maximums
and
(b) case-expansion readings that DON'T indicate excessive pressures, when the pressure guns indicate pressures at AND ABOVE proof-load levels -- DANGEROUS loads that case-expansion readings do NOT detect, for example 70,000, 75,000, even 90,000 lb/sq in. in cartridges SAAMI-rated at safe only below 60,000 lb/sq in.

So my opinion of case expansion's worth doesn't matter. The facts do matter. And I don't have to have discovered those facts myself. Also, my acceptance of these facts isn't determined or affected by the dissenting opinions of otherwise well informed and intelligent people who happen NOT to have learned these same facts.

So my opinion is that the statement "Case expansion is a dangerously misleading and undependable method of trying to 'read' peak chamber pressures" is a well and repeatedly proven fact, based on well and repeatedly proven facts (not opinions based on old, opinion-based writings). I also opine with some confidence that this opinion is sturdily supported by enough repeatedly observed facts to qualify it as a final opinion.

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Originally posted by jackfish:
When pushed about his statements Ken Howell continued:

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And being immensely privileged to be privy to a lot of factual findings -- both classic and recent -- about interior ballistics, factual material that hasn't found its way into the gun magazines and isn't obvious enough that every opiner in print or cyberspace sees its validity at first glance, I feel duty-bound to share the impact of these facts even though such sharing inspires onslaughts of doubts and dissenting opinions. It's worth noting, IMO, that none of these doubts or dissenting opinions comes from a dependable, well equipped experimenter who has tested and examined the validity of case expansion with good pressure-measuring equipment.

When several careful and dependable experimenters, each well equipped and confirming the others' findings, report that miking case expansion to "read" pressure has in their experience produced two significant bodies of serious error, I take all that as observed fact, not conjecture or opinion.

Those two bodies of repeatedly observed error are --
(a) case-expansion readings that indicate dangerously high pressures, when the pressure guns indicate pressures well below maximums
and
(b) case-expansion readings that DON'T indicate excessive pressures, when the pressure guns indicate pressures at AND ABOVE proof-load levels -- DANGEROUS loads that case-expansion readings do NOT detect, for example 70,000, 75,000, even 90,000 lb/sq in. in cartridges SAAMI-rated at safe only below 60,000 lb/sq in.

So my opinion of case expansion's worth doesn't matter. The facts do matter. And I don't have to have discovered those facts myself. Also, my acceptance of these facts isn't determined or affected by the dissenting opinions of otherwise well informed and intelligent people who happen NOT to have learned these same facts.

So my opinion is that the statement "Case expansion is a dangerously misleading and undependable method of trying to 'read' peak chamber pressures" is a well and repeatedly proven fact, based on well and repeatedly proven facts (not opinions based on old, opinion-based writings). I also opine with some confidence that this opinion is sturdily supported by enough repeatedly observed facts to qualify it as a final opinion.

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376 steyr 2538 at est57,700psi (68 grains of powder)
375 HH at 2598 at est57,700psi (78 grains of powder)
375 Jamison 2557 "" "" (70 grains of powder)

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Originally posted by jeffeosso:
Jackfish,
once again, you are completly avoiding the issue, and attempting to cloud the issue with generalities.

the only thing that you've given, as a fact in your load development, is that you rely on a sticky bolt and primer condition.

You remind me of a guy at the range, that aciidentily points a barrel to the side, and then get's pissy when someone calls him on being unsafe.

let's make it again clear, that 375 HH balistics MEANS 300gr at 2500fps. I have no doubt it can be loaded hotter. But when one says "it matches 375HH" they don't mean it matches 375 weatherby.

the 375 jamison has a case capacity, empty, of 85 grains. With a 300gr woodleigh bullet, it has a USABLE capacity of ~70.3, at rick's suggested max OAL of 2.860"

the 376 steyr has a max capacity of 80 grain... and with the same bullet, it's usable is about 68.5, at again, the factory 3.110 maz oal.

WOW!!!... less than 2 grains of water capacity...
let's look at the 375 hh... a WHOOPING 2.5% difference in case capacity ... WOW

95 grains max, 83grains usable... SURE it can go faster... and has ~ 15% greater case capacity, usuable, than the jamison, and a huge nearly 17% more than the steyr.... an amazing 2% greater useful capacity....

wow.. that's just amazin'... cases that have NEARLY THE SAME CAPACITY can have nearly the same velocity... wow.. aren't you stunned?

"oh it can be longer" but not the the chrimpgroove, and therefore not, IMHO, a dangerous game loading practice.

of course the 375 HH can be loaded hotter than either of these cases can ever be loaded SAFELY...

but can either one match the 375 hh factory stuff? sure can... can it be done safely... sure can...

<yawn>
Do as you please, jackfish... you certainly prove that you will

jeffe

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60.0 2471 av
60.5 2491 av
61 2529 av *** chosen load to develop *** casehead .00275" new brass
61.5 2538 av WARM casehead .003" new brass
62 2559 av HOT IN NEW BRASS, very warm in once fired. casehead .00325.. STOPPED too much for me

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Originally posted by jackfish:
Theory vs. a pressure test barrel. Hmm, No thanks, I'll go with the pressure tested load.

jeffe, info, where's the info? Afraid one might actually be able to evaluate what you have presented? Oh, I know, you might think too much information is a bad thing.

What were the powders used in the Quickload estimates for the 376 Steyr, 375 H&H and 375 Jamison?

What was the powder used for the incomplete 376 Steyr load data you presented?

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60.0 2471 av
60.5 2491 av
61 2529 av *** chosen load to develop *** casehead .00275" new brass
61.5 2538 av WARM casehead .003" new brass
62 2559 av HOT IN NEW BRASS, very warm in once fired. casehead .00325.. STOPPED too much for me

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: http://www.chuckhawks.com/376steyr.htm
According to Hodgdon reloading data, handloaders can equal the performance of the Hornady factory load giving a 270 grain bullet a MV of 2610 fps using 65.5 grains of VARGET powder, and achieve maximum velocities of about 2910 fps with the 225 grain

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with a 24" barrel, 376 steyr, and BOOK loads

300 grains at 2500+
230gr at 2800+
225 at 2900+

and all submoa

Jeffe

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yep..it's out there...

www.416taylor.com has load data for it...

btw, 376 steyr duplicates this

jeffe

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Seems a little hot to me, as I am getting 2950 from 225 grains...

I like varget/rl15/748/benchmark for my 376... and it shoots well.s

Mebbe the barnes blue pills are lubed enough to help with the pressure, but I dont think I would drive em past 2800.

jeffe

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Okay,
Here's the wicked deal
I took a mexican 36 action a NICE walnut stock, bold trigger, leupold 1x4 IIc (updated the reticle) and did it in 376. It feeds PERFECT

anyway, i did a SLOW inletting... look about 12 evenings, and then bedded it with acragel. It's going off to be blued in a week or so, but....

it shoots GREAT... with book loads, and book lengths (235gr speer, 66 gr varget, win mag primers, set to 2.060 est vel 2750, ME about 3900, and est pressure is "nominal, but can go MUCH higher") with a 4x scope, shots, 5, 6, 7, 8, 9, and 10 all hit in a 1.2" group at 100.

Since I normally shoot a 416 rem, the recoil felt like a 308.

Like I said, it's going off to be blued and then I'll start doing real load dev.. like measuring distance to Lans, and playing with powders and bullets. My goals are 1: 235 speer at 2850, 2: 300 gr X or solids at 2400. I think it's more than possible, and subinch at that.

there ya go, my african light rifle.

Jeffe

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: http://www.chuckhawks.com/376steyr.htm
According to Hodgdon reloading data, handloaders can equal the performance of the Hornady factory load giving a 270 grain bullet a MV of 2610 fps using 65.5 grains of VARGET powder, and achieve maximum velocities of about 2910 fps with the 225 grain

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: http://www.chuckhawks.com/376steyr.htm
The 225 grain bullet is a reduced power (and recoil) load and also features an advertised MV of 2610 fps with ME of 3325 ft. lbs.

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Originally posted by jackfish:
So jeffe is 40 fps over what Chuck says is possible. Is that possible? HA!

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http://pw1.netcom.com/~chingesh/AH376DGLoads.html
.376 Steyr Scout, 61.4 grains IMR 4895

Bullet (Hornady) 300-gr RNSP
B.C. = .250
300-gr RN Solid
B.C. = .275

Average Velocity (ft/sec) 2325

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Originally posted by jackfish:

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yep..it's out there...

www.416taylor.com has load data for it...

btw, 376 steyr duplicates this (375 epstein, that is)

jeffe

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Seems a little hot to me, as I am getting 2950 from 225 grains...

I like varget/rl15/748/benchmark for my 376... and it shoots well.s

Mebbe the barnes blue pills are lubed enough to help with the pressure, but I dont think I would drive em past 2800.

jeffe

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SHOT IT TODAY!@!!
These loads, of course, are not for anyone to every use.

This is unreal, but these are the results I got at the range with my 376 steyr, 24� barrel, about 80degrees

Reloader 15, 300 grain hornady, incrementing loads 0.5 grains, starting 3.095�

forgot to include the casehead expansion
59.5 2460 av
60.0 2471 av
60.5 2491 av
61 2529 av *** chosen load to develop *** casehead .00275" new brass
61.5 2538 av WARM casehead .003" new brass
62 2559 av HOT IN NEW BRASS, very warm in once fired. casehead .00325.. STOPPED too much for me
BTW,
The 235gr speer with 66 gr of varget,
2803 av

Holy COW, I am matching the 375HH, with my short action 376, and it's PLEASANT to shoot. It's 2/3 my 416, felt. I shot 20, and my buddy shot 16. It was GREAT.

The 235s are as flat as a 3006 with 165!!

Lots of looks and stares, but no takers to shoot.

Shooting Chrony Beta Master, 80 degrees, 10 or 11 feet. Index load of right at 2800 with a 284 used to verify.

I am PUMPED and I'll keep you guys posted.
jeffe

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big for forums
x-caliber
One Of Us
Member # 9681

posted 07-19-2003 05:45
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I was wondering if there is a wildcat that is based on the .338 Winchester Magnum necked up to hold .375 diameter bullets. If so where could one find loading data and ballistics for such a cartridge. It would appear that if this cartridge exists, the performance level would fall somewhere in between the 9.3 x 62 and a .375 H&H. Plus it would fit in a standard length action.

Thanks for any help guys...X

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"It is often better to remain silent and appear as a fool than to speak and remove all doubt."

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Posts: 172 | From: Georgia | Registered: Oct 2002 | IP: Logged

jeffeosso
One Of Us
Member # 8427

posted 07-19-2003 05:52
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yep..it's out there...

www.416taylor.com has load data for it...

btw, 376 steyr duplicates this

jeffe

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Originally posted by jackfish:
Your 235 grain load exceeds published 24" barrel velocity by 65 fps with 2 grains less powder. So you do have a habit of exceeding published figures.
happens.. that's why one chronos

It is easy to go back and edit posts to try to cover your tracks, the quote about the 416 Taylor is right from your post.
right from my post, in answer to a qeustion on the 375x338, as seen in above. Take a look at the "edit" date... been there awhile. I included the entirely above.

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