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Originally posted by Paul5388:

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I believe I saw a post by Ken Ohler where he was going to see what kind of pressures could be seen in primers and the pressures were so high, he scrapped the idea of an article on it.

I didn't state this very well. He experienced very high pressures, before any indication was seen on the primers, was what I was trying to say.

I think there would be a head separation before the primer would be left partially unseated. That's probably what you see in Jim's (jfh) pictures of his 640. the firing pin not only ignites the primer, but also drives the case forward in the chamber. If the pressure reaches catastrophic levels, the case is "welded" to the cylinder and the head separates from more head space than the brass can stand.

That Paul is exactly the point I was wondering about. There could be a point in working up a load, with different brass, where theoretically the event I discribed could occur. Granted not likely but possible.

As I quoted before from the "Pressure" section of the Lee 1st it talks about him experiencing the same type of thing. I'm not sure if he was only reading the primer, I'll have to reread it, or if he had actual pressure testing equipment. What he did was test the results of compressing charges.

At any rate this make sense.

JFH, were the cases seperated when you opened the cylinder or did you break them when you tried to drive them out?

This is just for informational purposes and to compare primer photos.

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Here's a picture of some .357 Max brass shortened to 1.50" that was shot in my .357 Mag Handi rifle.



I shot these with 12.0 gr of SR 4756 and a 195 gr LSWCGC and 13.0 gr with a 358429 (these loads are probably only suitable for .357 Max guns). I was just test firing to see if they would work and to see what the primers and brass looked like after shooting. As you can see, the primers aren't flattened any at all and no cratering, but these are CCI 400s. They don't look anything close to the degree of flattening I saw recently on some "by the book" H110 loads. Extraction wasn't a problem either and there wasn't any leading, so these are due to be put through the chrony.

Paul,

Very healthy looking primers. I am not familiar with Handi rifle. Is it a bolt action? Or more specifically is there a room for primers to back out of the pocket and then get reseated. Just trying to get back on the idea that unseat-reseat cycle is required for significant flattening.

Mike

I'll recap the 640 overpressure incident again here, to get all the information in place.

First, the 'incident' consisted of shooting a cylinder full (five) rounds of a 38+P special load using AA#7 and the Speer GDSB135JHP bullet. Per Speer's specification, the powder charge was intended to be 8.2 grains, and due to a reloading error (NOT a double-charge) about 17-18 gr. of AA#7 was dispensed. (Newly returned to reloading, I did not recognize the charge size when I built them.)

I built 10, shot 5--and the recoil was big, and heavy, and rolling--but I have felt stronger recoil with the hot factory 125-gr. ammo. Then I went to extract them--and found the cases stuck. That results are shown in the picture smith crazy references, found here.

The first two cases were snug, but the next three were stuck. Tapping on them with a range rod separated the heads; they were not separated in shooting. However, they did separate increasingly easily, so to speak--that is, I used a small brass hammer on the range rod and light taps round 3, but round 5 separated easily with one or two light 'plunges' of the rod alone.

FWIW, I think the order of firing of these heads, from left to right, is 2-1-3-4-5. I still have these parts and may confirm that when I get around to anal-yzing them further.

Jerry / lovesrugers at handloads.com ran his pressure calcs for me and came up with 55,000 to 72,000. With that knowledge, and given the appearance of these primers, I relegated reading primers to the value of reading goat entrails obtained on a moonless night.

The 640 shot OK after I got the stuck cases out (careful work with the range rod on the bench drove them out, with no scratching or damage to the cylinder. But, latching was difficult to do, and there was minor sticky extraction with medium-pressure loads. My gunsmith / friend checked the gun out, and he found the chambers were expanded--you can see that in this picture.

Since it was a new gun, I sent it in to S&W for repair, and I included a copy of Speer data sheet I was following and identified it as an "overpressure incident."

Three weeks later I got the 640 back with a new cylinder and barrel fit. I've since fired about 5000-plus rounds through it--nearly all the Speer 38+P "replica loads" I build.

So, that's the long-winded answer to your question, Smith crazy. I got curious again as I started following this (latest) 4756 discussion, and I am looking closely at primers as I work my way up the 4756 / 158LSWC-HP development loads--but I don't consider it to be reliable information.

I do wonder, however, if primer appearance in conjunction with case measurement might reveal some correlations, at least with the data from one firearm.

Jim H.

Mike,
This is a picture of Paul's rifle. Not sure if this is the same one he shot these out of but it is typical of a Handi. We used to call them H&R Toppers.

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jfh: Since it was a new gun, I sent it in to S&W for repair

Jim,

Thank you for the recap. Very valuable report - thank you for taking time to write it.

I thought 640 was available only in stainless but in your pictures it appears black. What is dash number and is it rated for 357 magnum or 38 spl +p?

Mike

Skip,

Very nice looking rifle!

Mike

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I do wonder, however, if primer appearance in conjunction with case measurement might reveal some correlations, at least with the data from one firearm.

Jim,
I think that is the right track to evaluating overpressure problems.
Do you have a chronograph? That would be another useful tool if you are working up loads outside of published data. I wouldn't be without one.

By the way, please call me Skip. Anything with "Crazy" in it may be too apropos!

By the way Paul, I am anxious to hear what the velocity was. What was point of impact difference with the two loads?

rozenbem: The "black appearance" in the first picture is merely an artifact of the on-camera flash I used and the D80's auto settings--I didn't color correct in PSE except to enhance the exposure for clarity of the cartridges.

The 640 is a standard current model--the -5?--and fitted with a CT-305 (long) grip. With about 5000 rounds through it now, it is a real pleasure for trigger control and still feels tight.

skip: Yup, I have a chrono. The "overpressure" incident happened very early on in my return to reloading last year, and at that time I had not yet dug the chrono out. Further, I set an objective of "replica" reloading to match the Speer 38+P GDSB 135-gr. factory round and was using subjective recoil evaluation.

The goal was to produce rounds to acclimate to shooting the (carry) M&P340--so to that end, I wanted a practice round that felt like the carry round, as well as one that I could tweak readily for acclimation. To that end, I was very successful initially with just the subjective evaluation, and it was after the tweaking for various powders was done that I went to the chrono. Now I have lots of data from both types of shooting.

Jim H.

1st, the picture Skip posted was one of the other incarnations of the .357 Mag barrel. That was my ".357 Mag Carbine", built along the lines of the new H&R .45 Colt Carbine. It was a H&R Buffalo Classic receiver and wood, but it now resides on an older H&R shotgun receiver that is, for all practical purposes, a Topper.

The pictured receiver now has a 22" .38/55 "Target Model" barrel on it that was shortened to that length. This is the way it looks now, except it has a holographic sight on it instead of the red dot.



Second, the barrel to receiver gap is <.001" in its present configuration. However, the ejector is countersunk, as is the portion of the chamber intended for the case rim, which makes about .008" of "head space", or an amount comparable to a revolver. The chamber, as cut by NEF, will accept cases 1.5" long. So, I cut Max brass to the length of the chamber, to gain the extra capacity. The original H&R Topper was chambered for a short time in .357 Max, so it really isn't a risky type situation.

It (the .357 Mag Handi) makes a wonderful test bed for accuracy purposes, since it will easily demonstrate the potential of a cartridge, with the 3-9X scope on it. I frequently shoot 100 yard groups with it, to test longer range accuracy of a particular bullet/load combination.

Thank you, Jim and Paul. It is a beautiful rifle!

Mike

Here's a short telephone camera video of the .38-55 being shot with Shockey's Gold black powder substitute. My granddaughter, who was taking the video, jumped when it went off, but it's crumby quality video regardless.



Just click on the image to make it load, it's only 151 K in size.

Gentlemen,

In preparation for trying THE LOAD (what is it BTW? – there are several versions mentioned in this thread) I started doing some research. Downloaded all data for pistol calibers from Hodgdon web site and plotted it. Picture below shows Hodgdon maximum recommended pressure for all bullets and all powders in 357 magnum (pistol) caliber.



Data points colored red are values measured in CUP; colored blue – in PSI. Circles are lead bullets; squares – jacketed bullets. Bullets’ weight and type are not shown in this view.

One thing that caught my eye was that Hodgdon recommends very different pressure limits for various bullet/powder combinations in the same caliber. The limit ranges from 9,000 CUP for 90 GR. CAST LRNFP/TG to 43,000 CUP for 140 GR. HDY XTP / HS6. Not sure why - their web site says that internal testing is limited to velocity and pressure readings.

Just thought it’d be an interesting view to share. There is no new information here, but as they say – “seeing is believing”…

Mike

That's an interesting chart, Mike.

Having said that--I would re-do it into several charts, one for each bullet weight.

Here's some other information to ponder. Following a discussion on THR about good powders for 2" barrels, I recently started looking at powders by density as well as burn rate.

I found this *.pdf chart that is noticably different from the Hodgdon chart. I still don't know how to use this data--but I have found, based on my 38+P / 357-lite "replica loads" project that its ranking fits in better with my results than the Hodgdon burn rate rankings.

You should also read carefully this thread (and the earlier 4756 ones) about published data changes over time. Quite honestly, I now consider the Hodgdon data inappropriately conservative for intelligent decision-making.

Jim H.