The 1973 edition of Gun Digest has an article by Wm. Caldwell entitled "Pressures and the revolver". Mr. Caldwell worked in the Speer lab during preparation of the data for Speer manual Number 8. The article discribes how pressure data was obtained in preparation of Speer manual number 8 and why velocities are reduced by cylinder/barrel gap but pressures are not. There is specific data on bulleye, unique, and 4756 powders in 38/357.
Those folks who continue to use speer manual #8 as a data source should find this an interesting read.

quote:

Those folks who continue to use speer manual #8 as a data source should find this an interesting read.

Thanks leon, I'll have to run down to the local Borders and buy a copy.

I just read the article and it certainly puts those who deny pressure testing for Speer #8 in an awkward position.

I'll see about scanning the article in and posting it on my web site.

You mean the Speer Technician I spoke to was actually putting this old flatlander on?

I'm going to have to find me a copy of the '73 GD and read it. Thanks.

Speer #8, first Edition, was copyrighted in 1970. Gun Digest for 1973 was actually copyrighted in 1972, so there's only 2 years difference between the two publications.

Here's the beginning of the "Pressures and the Revolver" article.



The rest of the article can be found at this site.

http://www.bbhfarm.com/gallery/album18

There is more than one way to read that first paragraph. I know how I want to read it!

This information is going to need some digesting!

An interesting and informative read. It shows that Speer was doing pressure checking around the time that the Speer #8 manual was published.

Speer #8 first edition data still makes me nervous. That is the only version of it I have. For example.

Current Hodgdon 357 Magnum 158 grain JHP data for SR4756.

Start 5.0 Gr for 17,500 PSI, 896 FPS
Maximum 6.5 Gr for 29,900 PSI, 1146 FPS

Speer #8 First Edition 357 Mag 158 Gr JSP Data, SR4756.

Start 10.5 Gr for 1187 FPS
Maximum 11.5 Gr for 1254 FPS

Speer #8 38 Special Data, SR4756, 158 Gr JSP

Start 8.5 Gr for 1072 FPS
Maximum 9.5 Gr for 1177 FPS

When the starting load in one manual for 38 Special is 2 grains higher than the maximum in a current manual for supposedly the same bullet weight and powder in 357 Magnum I have to question the older manual. Particularly when way above the powder manufacturer's data published at the time as was shown in another thread.

What was the difference in testing methods? I do not know but with that large a discrepancy I am inclined to believe that something major was wrong somewhere.

Particularly true as for 4227 the data between Speer #8 and the 2008 Hodgdon manual for 357 are almost identical with the 158 grain bullet. Starting loads are the same but the Hodgdon current manual lists a maximum load .5 grains more than the old Speer manual.

I have always read that when there is a question regarding reloading data then multiple sources should be cross referenced and data which appears out of line should not be used. Better safe than with a damaged gun. In the case of Speer #8, me chicken.

Rich,
I can tell you first hand that there is no way they got those velocities with a revolver. I wanted to load some when all the Speer #8 for the 38spl threads started. I loaded the 6.5gr and got 980fps from my 586 and 686 6"bbls. In order to get the velocities they espoused I had to go to the 9gr area. I loaded just over that with my homecast 160gr LSWC and got 1280fps out of those firearms.
I also have loaded the data for the 158gr LSWC, not the jacketed data, with my bullet and got 1180fps out of a 3" M60.

The reason they got so much more velocity from less powder is found in the article. The thing to decipher though is the time factor.

I don't want to discuss this though until I get a grip on it myself. Just gotta think it through.

I suppose it's entirely possible Hodgdon is using worse case scenarios to jack the pressures up. Maybe the loads they show are taking that into consideration, or maybe not.

This page clearly shows the 110 gr load Speer #8 uses of 15.0 gr of SR 4756 (1662 fps according to Speer #8) at 33,048 psi transducer pressure.



Hodgdon says this when using a 110 gr XTP.

quote:

110 GR. HDY XTP IMR SR 4756 .357" 1.590" 6.5 1292 18,500 PSI 8.5 1574 32,700 PSI

Now, if one was to load said 8.5 gr of SR 4756, do you really think it's going to produce 1574 fps? If it gets anywhere within 200 fps of that figure, you might be able to believe the pressure numbers, but I don't think it'll even get that close to what they say.

BTW, Speer wasn't using a proprietary bullet for that test, it was probably either a Super Vel or a Sierra.

I agree that Hodgdon test velocities seem to be from unvented test barrels. Many are also fairly long barrels per their published data.

I am looking more at maximum powder load quantities in grains with the same weight bullets when comparing the Hodgdon loads and the Speer #8 ones. Too large a discrepancy there it seems. I expect to see differences there between different manuals due to bullet, primer, case manufacturer/lot and powder lot variations as well as crimping differences but NOT to the extent evident here.

Also wondering why with the slowest powders both current Hodgdon and Speer #8 data are so close but not with some faster ones unless case capacity is the limiting factor.

I note that HS6 load data is much more comparable between Speer #8 and the Hodgdon current data than SR4756 data. The Speer listed HS6 loads are routinely using more powder but not to the extent of the SR4756 loads.

Just my observation that the Speer data in their #8 manual seems to disagree with ALL other load data I have seen for SR4756 and I want to understand why and if the Speer load data is safe in ALL guns. The one reported SR4756 pressure test mentioned in the earlier thread makes me wonder.

Does any one know if the early Speer transducer test barrels would match current SAAMI specifications as far as transducer location and calibration methods is concerned?

My backfround is as a quality assurance and reliability engineer and this question interests me.

BTW if someone wants some loaded ammo tested I note that H P White test lab is still in business. Here is a link to thei web site.

Link

Rich,

This may interest you on .38 Special loads from the Sierra 1977 Edition.



You'll probably notice the 158 gr load includes what has become affectionately known as "The Load". Sierra used a 6" K-38, just like Speer did 7 years earlier in 1970.

Here's the 2nd Edition of Speer #8 that covers their 158 gr JSP.



With a 6" M28-2, I clocked 1160 fps with 8.5 gr of SR 4756 (2004 vintage), but I was using a 158 gr LSWC, which would normally be a little faster than a jacketed bullet. Regardless, the two publications agree pretty well in this contested area of data and my velocities are very close to what they got. this leads me to take what they say over the preposterous numbers Hodgdon is publishing now.

Sorry about the size of the images, but I was trying to get the Sierra big enough to read it.

Interesting data. Looks like Speer is the same as the first edition of #8. Sierra's data is over 1 full grain less for SR4756 with the 158 grain than Speer. I do have the old Sierra manual too.

I would note that Ken Waters in Pet Loads from Handloader lists the factory 38 Special loads available at the time of the article. The fastest are 158 grain at a factory claimed 1090 FPS. These are the old HI Speed loads intended for the 38-44. The article is from 1966. Your loads are above that in speed.

I strongly suspect that the loads listed with a 158 grain bullet at over 1000 FPS from all of the manuals of this era are basically 38-44 pressure loads. They are gone from Sierra #3 I note. I certainly would not care to try them in a pre WWI K frame.

Hodgdon, and other manufacturers, now feel they have to stick to current SAAMI pressures suitable even for the oldest guns. If their almost 30,000 PSI data for a 357 load of 6.5 grains of SR4756 with a 158 grain bullet is even close to correct then I do not want to exceed it in a 38 Special non +P rated gun. It is a relatively fast powder listed in burning rate charts between AA5 and 800x.

Some may feel that current reloading data has been emasculated. Possibly true but at the same time remember that both test methods have advanced and the liability atmosphere has worsened. Also some loads such as the old 38-44 may not have ever had a SAAMI spec. Even if there was it has to have been well above current 38+P pressure limits.

The old data is still out there and available so people are free to use it if they want. I am leery of the loads which list high velocities with relatively fast powders personally.

I never understand why some people seem so intent on turning their 38 Specials into 357's. If you want 357 performance just buy one.

I also can't figure out why people are satisfied with Daisy BB gun ballistics out of their .357 magnums.

I don't shoot these .38 Specials in anything other than .357 Mag revolvers. However, they are still better in terms of real world velocities than most factory .357 loads.