Help loading a non-neutered .357 magnum...


April 18, 2009, 08:57 AM
I am looking to replicate the original .357 magnum loading out of a S&W Model 27 8-3/8" bbl. I have historical data indicating that this load was a 158 grain LSWC, 15.4 - 15.8 gr. of pre WWII vintage 2400 (depending on batch), and a large primer.

My problem is, I always try to stay within the load limits published in reloading manuals, and nothing published today even seems to come close to this load using 2400 (granted modern 2400 is different than pre war 2400, but not that much different right?).

It is a matter of record that SAAMI has reduced the maximum pressure specs for the .357 dramatically over the years, resulting in a "neutered" .357.

Yet if the gun I am shooting existed during the time the pressure specs were higher... shouldn't I be able to work up to the old recipe? If it was "safe" in 1940, why shouldn't it be safe today?

If anyone knows of published data from a reputable company which will give 1500 fps with a LSWC using 2400 out of an 8" bbl, could you please share it, otherwise can anyone tell me why I should not work up to loads published in old manuals if I am shooting an N frame Smith...

Were the .357 pressures dropped to 35K merely to allow the round to be safely fired in J and K frame .357's... neither of which I am using?

I would really prefer to stay with 2400 as I have a ton of it... and I have old data saying I can use it... but I want to be safe... what say you?

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April 18, 2009, 09:30 AM
I think you answered your own question.

You have old data.
You have new 2400.

My problem is, I always try to stay within the load limits published in reloading manuals
This is not a "problem." This is "SAFETY."

If you "always" do this, then continue to do so. Consult your manuals (you do have paper manuals, yes?) and do what it prescribes, carefully working up full-house loads, watching for problems as you go.

If you want that hot of .357 loads, my Lee MODERN RELOADING 2ND EDITION manual does show a max charge of 2400 that will will break 1600fps, but I don't know barrel length. The story is Lee gets his data from powder manufacturers, so check Allaint's website and see what it specifically recommends.


April 18, 2009, 09:41 AM
A lot of the old data was done without pressure testing. Find an old manual, and take your chances. Why do you want to shake a perfectly good gun loose prematurely anyway. JMHO :)

April 18, 2009, 10:32 AM
Thanks for the replies so far...

I guess my question can be distilled down to the following:

If I am shooting a S&W N-Frame, or Ruger Redhawk, why should I limit myself to the modern 35K SAAMI spec, when the spec used to be 40K or more?

Is modern 2400 that different than pre-WWII 2400? Surely S&W did some pressure testing before releasing the .357 magnum loading in 1935?

Alliant's website lists no 2400 loads for LSWC... I will check out Lee's 2d edition... Thanks Quoheleth

By using pre war load data an I abandoning safety in the .357 magnum, or by changing the data did SAAMI abandon the "true" .357 magnum?

April 18, 2009, 11:15 AM
Pick up a copy of the Speer Manual #8 on Ebay.

It was the last manual they did without pressure testing equipment.

I think of it as the Speer "Proof Load Manual."

Use at your own risk. Most of the loads for handguns in there are significantly hotter than what's published today. Some (like the 38 Special "defense" loads) are just plain dangerous.

Old Fuff
April 18, 2009, 11:45 AM
A difference in the powder is one issue, but a bigger one is the way the cartridge cases are or were constructed. The early cases had what are called "balloon heads,” and were formed out of sheet stock much in the same way as .22 rimfire cases are today. Those case heads were very weak by our standards, and are the reason that the Smith & Wesson cylinders had chambers that were recessed to support the case head.

By virtue of this construction the case powder capacity was greater, so in theory if not practice, a particular charge of powder produced less pressure then the same charge would in a solid head case of the kind made today. Solid head cases made it possible to make .357 Magnum revolvers and not have to recess the heads, but one should always reduce the charge if working with old data.

The original round used a soft-lead 158 grain semi-wadcutter bullet with a true muzzle velocity of between 1450 to 1510 FPS out of a 8 3/8” barrel. That odd barrel length came about to make the sight radius an exact 10 inches – the maximum length allowed by NRA rules for bullseye match shooting. The powder charge was 15.3 grains of #2400 powder in balloon head cases. DO NOT TRY TO DUPLICATE THIS LOAD IN MODERN CASES!

If you had ever shot any of these you’d know that it was a lousy one. The combination of high pressure (in the 45,000 psi range) combined with a soft lead bullet, resulted in quick and excessive barrel leading. Making an exact duplicate would not be a bright idea.

When the original .357 Magnum revolver was introduced, hand loaders in general, and Elmer Keith in particular solved the leading crisis by going to hard cast lead bullets in place of soft ones swaged from lead wire.

Keith also discovered that when using N-frame Smith & Wesson’s a shorter-then-necessary cylinder made it necessary to crimp the case over the front shoulder of the semi-wadcutter bullet, rather then doing it right by crimping the case in the crimping groove. He and others solved this by loading Magnum level loads in .38 Special cases and crimping the bullet where it should be crimped. This is a good practice, but only necessary with some S&W revolvers. If you follow this practice, use high-end .38 Special loads, not those listed for .357 Magnum.

If you are going to use cast lead bullets (highly recommended) I suggest you get a Lyman reloading handbook. They list loads that approximate the original one, but before you load any, be sure the overall cartridge length will work in your model 28 S&W, and if you have to deep seat the bullet and crimp around the bullet’s front shoulder BE SURE TO REDUCE THE POWDER CHARGE AND THEN WORK UP TO THE LISTED LOAD WHILE LOOKING FOR SIGNS OF EXCESSIVE PRESSURE. If you see some, STOP!

April 18, 2009, 11:50 AM
Very informative post, Old Fuff.

April 18, 2009, 12:11 PM
Great post Old Fluff.

Do all the "pin-frame" S&W revolvers have recessed cylinders?


To CTSiglover: The Speer #8 Manual used a S&W Model 27 for load development in the 357 magnum. They used a 6" barrel.

April 18, 2009, 12:20 PM
Another aspect of this discussion is the fact that pressure testing equipment in use today didn't exist in 1935. When modern pressure testing methods were adopted, they found that pressures were much higher in some cases than they thought they were, hence the reduction in some loads.

Hope this helps.


CSA 357
April 18, 2009, 12:27 PM
The old loads leaded the barrels bad and very fast, gass checks and jacked bullets came latter and the rest is history, csa

April 18, 2009, 01:10 PM
1935, when the .357 S&W Magnum came out, was before my time, but I don't believe the .357 Magnum case was ever made with a balloon head.

Balloon-head cases were the norm in .38 Spl, .44 Spl, .45 Colt, and all other calibers of the time.
But not the .357 Magnum.

The very first ones did use Lg Rifle primers, not Sm Pistol primers though.

The original load was reported by some to be either 15.3, or 16.0 grains of what was then 2400 powder, a 158 grain soft swaged lead bullet, and a Lg Rifle primer. Pressure ran to 45,000 PSI or more as best they could measure it then.

My first .357 was a Ruger Blackhawk in 1961. I later got a S&W Highway Patrolman in 1963.
Winchester factory loads at that time were loaded with a 158 Lubaloy coated soft-swaged LSWC bullet. I don't know, or recall what the powder type or charge was.

The cases gave very stiff extraction in the Ruger, and had to be beat out of the S&W with a stick!

Barrel leading was severe after 6-12 rounds in either gun.


April 18, 2009, 01:22 PM
The first .357 Magnums were primed with large pistol primers, as were .38 Special brass. I still have some of them, and the primer pockets are too shallow to accept a rifle primer.

Other than that small distinction, rcmodel is entirely correct, and I second his opinions. I've seen, and possess, many balloon head .38 Special cases, but I've never seen a balloon head .357 Magnum case. I've been loading since 1963, and I'm an avid scrounger/collector. The balloon head cases were designed to be able to get more BLACK POWDER into the case, since the pressures are so different than smokeless powder, and more is required.

Hope this helps.


Old Fuff
April 18, 2009, 01:36 PM
Do all the "pin-frame" S&W revolvers have recessed cylinders?

For the most part, yes. But they're might be exceptions.

To this day, S&W never junked parts that were useable. So as long as older style barrels remained in stock they would use them, even though they had to be matched with non-recessed cylinders.

A lot is made over "pinned and recessed" revolvers vs. "not pinned and not recessed cylinders." So far as barrels go I agree, as I don't like the crush-fit method. However when it comes to head-recessed chambers I don't give a hoot.

They were unquestionably a good idea before, and shortly after World War Two, but when solid head cases became the order-of-the-day they are totally unnecessary. S&W kept them for a long time when they didn't need to, because it was an exclusive S&W feature. Colt, Ruger and Taurus never used recessed chambers, and they're revolvers didn't suffer for lack of them.

What Smith & Wesson should have done and didn't, was lengthen the N-frame .357 Magnum cylinders to match in length those used in the .41 and .44 Magnums. Then this business of crimping the case over the bullet's shoulder would have become a moot point. As a rule-of-thumb I prefer Keith's idea of using .38 Special Plus-P cases that have thicker solid heads, and crimping the bullet where it should be crimped. But if you do this using maximum loads, don't start there. Instead, cut the load 10% and then work it up to the point where it's best for your gun. Also keep in mind that this is something you don't have to do in all revolvers, just N-frame Smith & Wesson's with a cylinder length = 1.62 inches and having recessed heads, or shorter cylinders without recessed heads.

When changing to a new bullet/case combination it is always advisable to make a dummy first, and see how it fits in your individual revolver, regardless of make or model.

April 18, 2009, 01:40 PM
Speer #14 gives a starting load of 13.8gr of 2400 for their 158gr jacketed bullets, with a max load of 14.8gr (COLs 1.570" or 1.575").

For a Missouri Bullet 158gr LSWC seated to 1.595" COL (.400" of the bullet seated in the case with .315" sticking out of the case), QuickLOAD computes a maximum load of 2400 to be 13.7gr, with 13.2gr computed to give about 1500 fps out of an 8 inch barrel. I wouldn't feel uncomfortable with a starting load of 12.3gr of 2400 (90% of 13.7gr) behind this bullet and chronographing the velocities to see where I fall on the load spectrum. But ultimately it's your gun and your choice.

The leading you'll get (or not) in your barrel depends on so many variables that the only answer I can give you is "It depends." Try it and see. You may need to go with a harder (or softer) alloy, or go with a gas check bullet design.

I know that writers who shot the original fire-breathing .357 Magnum loads complained of quick and severe barrel leading. As I understand it, this was one of the first motivations (along with the .44 Magnum in 1955) for the bullet makers to produce jacketed handgun bullets.

Old Fuff
April 18, 2009, 01:50 PM
I've seen, and possess, many balloon head .38 Special cases, but I've never seen a balloon head .357 Magnum case.

Somewhere I do have an early Winchester headstamped .357 Magnum case that has a balloon head. At the time (1935) I don't believe any revolver cartridges were made with solid heads. If there were never any balloon head .357 cartridges made, recessing the cartridge heads would have been unnecessary in the first place.

Also at the time there was some discussion about the questionable practice of rechambering .38/44 Heavy Duty and .38 Outdoorsman rvolvers from .38 Special to .357 Magnum. Among the reasons cited to not do so was the need to have the case heads recessed (which you couldn't do in a .38/44 revolver) and the lack of special steel and heat treating used in Magnum cylinders.

Old Fuff
April 18, 2009, 02:12 PM
I fired my first "original" .357 Magnum cartridges in about 1949, and I believe the ammunition was from pre-war stock. It was made by Winchester, and had 158-grain "Lubaloy" soft lead bullets. It may be that whatever they had been lubricated with might have dried out. I believe it was wax rather then grease based.

After 6 rounds I looked down the barrel, and discovered that toward the back end of the bore it was no longer rifled... :what:

A cleaning rod and bore brush was brought into play, and the lead literally came out in strips! In a few minutes the bore looked like new, but I decided thereafter to shoot .38 Special to avoid the issue until I knew more about it. Besides, .38 rounds were much easier on my somewhat restrained budget.

Soon afterwards I became one of Elmer Keith's thousands of true believers. Hard cast bullets and reasonable handloads ended the leading problems. Following his wise advice will still do so today.

April 18, 2009, 02:37 PM
That's exactly the same experiance I had in 1961 with pretty new factory Win Lubaloy ammo.

I don't think the wax had time to dry out on mine yet!

BTW: I also think that crummy ammo had a role to play in the Model 19 forcing cone breakage problems when the jacketed 125 ammo started replacing it.

Imagine driving a 125 grain JHP Mag through a Model 19 barrel that had been shooting that 158 grain LSWC Mag ammo of the day!


April 18, 2009, 03:09 PM
My 1995 Alliant/Hercules book has the following .357 mag load from a 5.6 inch barrel, using 2400:

158 gr LSWC
Fed 200 primer
Minimum yes minimum COAL 1.580”
Max load 15.3 gr 2400 gives 1620 fps @ 34,000 psi
Book says to reduce above load by 10% for “start load”

If it was me, and it ain't......I'd try to find a second source that agrees with the above.

FjLee Denver CO

Ben Shepherd
April 18, 2009, 03:13 PM

The 357 magnum is my favorite caliber by far. I have a couple rifles and well over a dozen Ruger handguns chambered for it. I enjoy shooting full snort, full potential loads in it. I have spent many hours running thousands of rounds over a chrono with different load combinations over the last several years trying to wring every possible ounce of power out of this cartridge.

With that in mind-

Years ago, I was shown a note given to a police dept armorer by a Winchester rep on how to load the 357 magnum that was dated somewhere during 1937 IIRC. I do not know if it was for balloon or solid head cases however.


The charge was 15.8 grains of 2400 behind a 158 lead SWC. I worked up to it ONCE in one of my redhawks. Case extraction was very stiff, with no noted head expansion or primer issues.
Load work up went as follows-

Case: Federal
Slug: Laser-cast 158 HCSWC, seated to crimp groove, heavy crimp
Primer: CCI small magnum
Powder: 2400

In .2 grain increments, from 14.0 through 15.2 powder charge and velocity increase were linear. From 15.2 through 15.6, velocity gains slowed considerably, with extraction starting to get noticeably harder at 15.4. At the 15.8 charge velocity was actually lower than the 15.6 charge, and case extraction effort doubled. As far as recoil goes- That redhawk is a very big, very heavy gun, and with charge weights at and above 15.4 the felt recoil was very nearly the same as a 44 redhawk, with a very substantial increase between the 15.2 and 15.4 powder charge.

What that means is this- Above 15.2, I was walking on eggs. Period. With a powder that is less forgiving, one that I had less experience with, or a weaker firearm, I would have put the brakes on right there. And that 15.8 charge? STRAIGHT UP REDLINE DANGEROUS.

In other testing I've done, as well as some others here on THR between the old 2400 that's in little square cans labeled rifle powder, vs the new stuff in plastic bottles, identical charge weights show a roughly 50 fps faster velocity with the new stuff.

What this all means?

Powder formulation has changed, and pressure testing equipment has gotten much better.

We've been asked this kind of question before here on THR, and more than once I've typed this post up and then changed my mind and not posted it, as it is honestly outside the bounds one should EVER go. But since I understand where you're coming from having been there myself, and people keep asking this question I finally posted it.

Two notes:
1. Unless you are a handloader with a lot of experience I highly recommend you DO NOT pursue this.
2. If you decide to purse this and you do not have and understand how to use a chronograph correctly while working your load up, you're absolutely crazy.

Old Fuff
April 18, 2009, 03:55 PM
Minimum yes minimum COAL 1.580

Which is also the length of a S&W N-frame .357 Magnum cylinder that doesn't have recessed heads. Using a typical 158-grain LSW bullet and .357 case, you would have to crimp over-the shoulder rather then in the crimping groove if you were to be able to get the cartridge into a chamber without the bullet nose sticking out the front. Deeper seating would quickly cause pressures to peek at an unsafe level.

Ben Shepherd's observations and warnings should be carefully noted. When loading for a Ruger as he was, it is not necessary to seat the bullet for crimping over the shoulder, and seating the bullet out further would somewhat reduce pressures. Should someone make the mistake of duplicating the suggested 1937 Winchester load in a solid-head case and deep-seated bullet with current #2400 powder, - for use in a Smith & Wesson - one might come to grief very quickly.

Ben Shepherd
April 18, 2009, 04:29 PM
Old Fuff, exactly. I've edited my post with the complete information.

April 18, 2009, 05:26 PM
Thank You Ben and Old Fluff, that's exactly the information I was looking for. Your experience is appreciated, and will help me from making any potentially dangerous mistakes.

Based on a PM from another board member, it seems as if Alliant did at one time in the modern era publish a load calling for 15.3 gr. of 2400, Federal 200 (SPM) primer and a 158 gr. LSWC which they claim reached 1620 fps out of a 5.6" bbl at 34,000 psi with a COL of 1.580". This was found on page 69 of the Complete Reloading Manual for .357 Magnum, 2004 Edition. Can anyone confirm? This seems to be the same load fjLee posted above... but I would love to see just one other source at 15.3 with a SPM primer...

I can find nothing in the histories about any .357 magnum case ever being made with a balloon head, the recessed cylinders simply hearkened back to a time when high pressure loads could blow out the head, and thus the recessed cylinders were never a functional necessity, more like a "belt and suspenders" approach to "magnum" loadings. If someone has a solid reference to a .357 Magnum Balloon case or manufacturer post-1935, I would love to hear and if confirmed can add it to the histories... even a picture of the casing would be wonderful evidence...

Ben, if you still have access to speed data from your load work, can you share it, and does the above Alliant load look close to your speeds at 15.2 and 15.4 grs.?

I think based on the comments here I will work up to the Alliant load above looking for pressure signs and watching velocity, with a bullet sized to my throats, gas checked, and hard enough to prevent leading. Anyone see a problem with this.

Thanks Again everyone, Ben and Old Fluff especially... I really appreciate it!

April 18, 2009, 05:43 PM
15.3 2400 - 158 LSWC load was published in the 1996 Alliant Reloaders Guide I am looking at right now.
1,620 FPS @ 34,000 PSI.
No mention of barrel length, although I envision a long pressure test barrel without a cylinder gap.

No 2400 loads for that bullet was given in the 2002 edition.

I have great difficulty believing the 34,000 figure in a revolver myself, based on 47 years of loading .357 with 2400. It could certainly be true in a pressure barrel with no forcing cone that allows the bullet to slug up during the transition from cylinder to bore.

I might add, they don't say anything about the bullet used other then LSWC.

If you buy soft bullets, all bets are off.

It would be safe with a properly sized hard-cast Keith plain base or Ray Thompson Gas-Check type bullet.

I have shot a bus-load of them over the years at 15.0 grains.
Above that, I have found sticky extraction in several different guns.


Steve C
April 18, 2009, 06:39 PM
From Alliants online data saved on 8/8/97.

April 18, 2009, 07:14 PM
That's my load then... thank you all very much... and yes, I will work up to it!

April 18, 2009, 08:05 PM
Just a little more info from the "new" Lee Modern Handloading, 2nd edition, reprint 2008.

357mag 158gr. jacketed w/ 2400 max = 15.2
357mag 158gr. lead w/ 2400 max = 15.3

These are the highest max listings from any of my four reloading manuals.
I've shot 15gr of 2400 under 158 jsp's out of a 6" gp100 and they worked great.

I imagine that lead listing would be not fun to clean up after. :uhoh:

Ben Shepherd
April 18, 2009, 09:27 PM
My do-all load(Keep in mind I have all rugers and Win 94 rifles, no k-frames, colts, etc.) is 15.2 with a federal small magnum primer and the laser-cast 158 HCSWCs seated to groove with a firm/heavy crimp.

This load clocks 1550 on the button out of my 7.5" redhawk, and right at 1300 out of my 2 1/4" sp101.

Keep in mind that currently non-magnum primers are reccomended with 2400 and that 15.2 grain charge is right at or over current published maximums. So approach with caution and due dilligence

Most folks as well as most manufacters report better consistency velocity wise with the standard primers. In my case, I saw no improvement, and actually had trouble with cold weather ignition using standard primers. So I went back to magnum primers. Remember, each gun is a law unto itself however. YMMV.

Old Fuff
April 18, 2009, 10:13 PM
I would seriously question that load consisting of 15.3 grains of 2400 behind a 158 grain semi-wadcutter (obviously had to be deep seated to get a 1.58" OAL). going 1620 out of a 5.6" (?) barrel with pressure measured at 34,000 psi. When a similar charge in the original load produced 1510 fps with pressure running a 42,000 psi, and that out of a 8 3/8" barrel. Back in 1935 a S&W engineer recorded the muzzle velocity out of a 5" barrel @ about 1385 fps, which would be consistant with using a slow burning powder.

Anyone who desides to try the Alliants load mentioned above should cut the charge at least 10% and work up very carefully.

Lyman lists a load consisting of their #358429 /#2 alloy/168 grain (Keith) bullet @ 1422 fps using 13.5 grains of 2400 powder. Cartridge OAL = 1.647 (obviously bullet NOT deep seated) Test platform was a 10" T/C Contender. Chamber pressure is not listed.

Everyone be very careful...

April 18, 2009, 10:25 PM
Good point Old Fuff, but we preach as gospel the idea of not exceeding factory published loads- granted this is a max load and needs to be worked up - but who knows more about 2400 and its capability than Alliant... with a SPM primer no less. And they did publish it... the liability would be huge if the load pressure listed was not correct...

If we can't trust the powder manufacturer's load data and pressure measurements... who can we trust? I am starting to think there is more "art" than "science" to this reloading business.

Do you think the data is a typo? How would one know? I do note that Alliant no longer lists this load... is there something wrong with it? Makes me think your spider sense may be on to something...

Old Fuff
April 18, 2009, 10:51 PM
Well typos have been known to seek into reloading handbooks :uhoh: :eek:

One problem I have is they didn't explain what revolver or test barrel they used. I wondered about the odd length (5.6") barrel they specified. It is always a good idea to pick a particular load, bullet and powder, and check it in more then just one handbook.

Understand there can be some variance because different platforms and velocity/pressure measuring devices are used. But in the end it is always best to cut back from a maximum load, and work up to what is best in your own gun.

On more then one occasion I have been working up a load, and stopped short of the listed maximum because it was obvious Id reached maximum + in my gun. I have also found that on many occasions a load slightly (or sometimes more then slightly) under maximum is much more accurate then going all the way even if it is safe.

April 18, 2009, 11:41 PM
Using that Allaint data, I've run out to a little above max in an M-27 and right up to max in an SP-101 to see if anything changed.

My experience was that at 15.3 of 2400 grains, all grouping was lost in both guns.

The 27 got tighter and tighter to 15.3 with a minimum of right at 1.25" 5 shot groups at 25 yards off the bench. At 15.4, it opened up to better than 2.5".

In the 101, it got tighter and tighter to 15.0, and slowly loosened up until 15.2. At 15.3, the group doubled size from 15.2.

Instead of loading for power, load for accuracy within published bounds- going over the limits typically looses accuracy in my experience.

Now I load 15.0 of 2400 for both guns. It's deadly accurate in both, and the recoil isn't excessive in the snub.

Ben Shepherd
April 18, 2009, 11:59 PM
My experience was that at 15.3 of 2400 grains, all grouping was lost in both guns.

The 27 got tighter and tighter to 15.3 with a minimum of right at 1.25" 5 shot groups at 25 yards off the bench. At 15.4, it opened up to better than 2.5".

My Rugers were close to those results, most of them tightened in the manner you described. I got best accuracy right at 15.2, it opened up a bit at 15.4, and at 15.6, it turned into a decent looking buckshot pattern, and the 15.8 charge showing about the same as the 15.6.

Part of the larger groupings at the highest two charges may very well be attributed to me. The substantially increased recoil had me nervous enough I may well have been flinchy a bit, as after every shot I took a moment to make sure something hadn't let loose on the gun. I don't mind recoil, I own a couple 44's and at that point in time had fired 454 Casull and 475 Linebaugh on several different occasions. That's why I was nervous........A 357 that is actually heavier than an identical model chambered in 44 should not equal it in the recoil dept with both running full power loads! This heavy recoil was telling me I was WWAAYY up there in the pressure dept. with the 357.

It should be noted here considering our subject matter, that ANY time you see a velocity DROP with an increased powder charge that the powder being used is getting into pressure territory that it was not designed for, and pushing it any farther is VERY dangerous as the powder has ceased behaving in a predictable manner.

April 19, 2009, 08:13 AM
I wondered about the odd length (5.6") barrel they specified

1.6" of chamber/vent and 4.0" of rifled test barrel. Alliant used that length up until the latest revision on their online load information, at which point they stopped specifying the barrel length and chamber pressure. I'm going from memory, but I seem to remember they specifically noted that the barrel was vented. This would have been as recent as 2007.

They also broke the old link I had ( The new link is here (

Ol` Joe
April 19, 2009, 12:48 PM
The old std for the 357 was I believe 46,000 "CUP" and was later changed to 35000 "PSI". Old hand loads were also normally worked up useing head expansion and the other "pressure" signs we see in the manuals. Most labs had no proper equipment. That`s one of the reason Speer dropped their data from the earlier books. They found when useing proper lab equpiment they were way over on lots of their loads.
The factory had crusher equipment, but used unvented barrels of unknown lenght, likely 8-10" for their velocity claims.

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