Overpressure signs in a Model 66-3 with starting load data

[PzShrekt]

I’ve been reloading .357 Magnums for my Model 66-3 for a while now, I’ve always selected the lowest starting load data to ensure absolutely no overpressure or high pressure situations in my K frame.

Recently I’ve been using Hodgdon’s RDC since it gives pressure readings for loads in PSI.

I’ve always used AA#9 with a 158 gr Zero Bullet Company JHP, cases around 1.287”, with a loaded OAL of 1.580”. Primers are CCI 550s, or CCI 500s, brass is from once fired Starline Sig .357 125 vcrowns. Load is 12.3-12.6 grs of AA#9 which according to Hodgdon’s RDC which gives a starting of 12.4 grs at 31,500 psi, the max being 13.8 grs with 35,000 psi.

My issue is that even with a completely cleaned gun, and loads using standard and magnum primers, I’m getting fairly sticky extraction that’s hard to push out using thumb pressure, don’t have to use the power slap method to get the cases to extract, but still a bit troubling to me.

I’ve heard that chamber wall thickness can affect the stickiness of a case regardless of whether the load is close to max pressure, and even my downloads with 12.0 grs feel about as sticky as my standard pressure loads at 12.4 to 12.6 grs.

The question is, is that statement true? If I take my usual loads and put it into an N frame (with thicker chamber walls) would that decrease the stickiness of my loads?

 

[max503]

I use a starting load of AA#9 and a 168g SWC in 357 and don't go no higher.

My 10.X with a 168 sounds a lot milder than your 12.X with a 158.

 

[bruce381]

unless someone has overloaded this gun in the past and caused cylinders to bulge a little you are at MAX pressure drop half grain or more and retest.

 

[bruce381]

also you are UNDER max but your measure scale can be off
that much very easily and repeatability is probably plus minus a half grain anyway. I used to load max in my 66 and had to go down half grain under but now I go 1 grain under I never go to max anymore, you are too hot, tolerances vary what is in the load books ALL say take with grain of salt and LOOK for over pressure you are there.

 

[243winxb]

My Maximum load - 357 mag Model 28-2

My worked up 357 mag load with no 9 is 12.1 grs of St Marks powder and my home cast 163 gr lswc , mag primer. Starline 357 Magnum Brass.

 

[243winxb]

confused- Brass Used?

Whats this got to do with a 357 mag?? (confused)

"brass is from once fired Starline Sig .357 125 vcrowns." ?? Wrong Brass?

 

[jem102]

I have always used the effort required for extraction of spent cases as the pressure indicator for revolvers. If they are "sticky" beyond moderate thumb pressure, it could be over pressure, sizing die not reducing body diameter enough, not far enough down the case head or the case is to long for your particular cylinder's charge holes regardless the stated spec. or tight throats... If you have a good mic what is the actual diameter of the bullet you are using? All these things can stack up and raise pressure.


First, if I had another sizing die I would try it or borrow one from a friend and try a different shell holder while your at it to ensure sizing the case head as far as possible.
Trim a few cases back to 1.285 just to be sure of length.
FWIW Hornady #11 shows 11.5 gr. as max for their 158 gr. using AA#9 which is quite a difference. You might try a few loaded 11.5 - 12.0 gr. to see what you get.


Hope this is of some help.

 

[jem102]

I think he is saying the current cases were first loaded with .357 Sig V Crown 125 gr. bullets.

 

[243winxb]

brass is from once fired Starline Sig .357 125 vcrowns.

Hope he is not using this brass.

 

[Piwo]

FWIW, I don't usually used sticking cases alone as a pressure sign. Nor do I use primer appearance as a sole guide either. An odd lot of soft brass can stick with normal loads. 357 mag cases fired in a gun that was fired with a lot of 38s can sometimes stick as well. Rough chambers or tight chambers can cause issues as witnessed by all the posts regarding S&W 22 revolver chambers. I try to look at the totality of circumstance in these cases (no pun intended). This assumes that I started with the starting load. You may also try firing them in another gun. But in any event, the component combination in your particular gun doesn't work.

 

[Alk8944]

My worked up 357 mag load with no 9 is 12.1 grs of St Marks powder and my home cast 163 gr lswc , mag primer. Starline 357 Magnum Brass.

What are you referring to as St. Marks Powder? St. Marks is a propellant manufacturing plant in St. Marks, Florida that used to be the Winchester plant. It is now operated by General Dynamics and produces several different propellants sold by Hodgdon under both their name and Winchester. I believe they produce some of the Accurate powders too. Among the powders made by St. Marks are HP-38/231 and H-110/296. There are others between the burning rates of these.

 

[243winxb]

Accurate powders, no. 5 & no. 9 were manufactured in many different countries. Different load data. Different burn rates.

Hodgdon is using the St. Marks powder manufactured data .

Hodgdon has safety data sheets (SDS) containing powder info.

 

[Yendor357]

The condensed version: Carefully, lightly polish your chambers.

And get a Garmin Xero. Information is power. Without a chrono, you’re just guessing.

 

[STORMINORMAN]

In the middle of the night, Miss Clavel turned on her light and said...

"Something is not right!"

So-called "START LOADS" shouldn't result in sticky cases: the load data start weight is probably the least responsible and the all these other variables (as outlined by those much more knowledgeable than I!) need to be identified & explored.

It could be a "stacking issue", but the amount of powder indicated as the "START" quantity would not likely be the issue IMHO.

Cheers!

 

[toad67]

Try putting some sized, unloaded cases in your cylinder and check those out for extraction. You might be chasing something that you can't catch, kinda like the undersized 22 cylinders. JMO, though.

 

[rwsmith]

Brass, ANY Brass....

...is supposed to expand to the chamber wall and spring back. Doesn't matter if it's thick or thin. Could you work up a lighter load with another powder and see where the trouble begins?

OR, magnum powders don't like to be downloaded, but if you use a magnum primer and work DOWN with Acc #9, you just need to be sure that your bullets all leave the barrel. I don't think that dropping back a half grain would be problematic outside of getting wider spreads on velocities. I worked down to a light load of Acc #7 (VERY carefully) for a project I undertook without difficulty. I haven't tried it with Acc #9 but if I had a good reason, I'd try it, with care. You are only going to be shooting them to help find the problem.

No need to load more than a few at the time for each level. And Chrono the results? I would surely check my scale, that's easy to do.

 

[PzShrekt]

New developments

So, I looked around and found out that Speer has the same load (with Speer bullets) calling for 12.3-13.7 grs of AA#9, but with a CCI 500 primer in .357 Mag for 158 grain JHP bullets.

I used 12.6 grs with CCI 500s, loaded to 1.580” OAL in my once fired PMC cases, Zero Bullet 158 gr JHPs, shot in my 4 inch Model 66-3.

The result? The damn cases tumble out the moment I tip the cylinder upside down. Recoil impulse felt softer, basically the same accuracy at 10 yards. The cases still in my cylinder only require a slight push of the ejector rod to come dropping out. I’m talking the same amount of pressure needed to run the ejector rod when the cylinder is empty.

Guess the whole thing about AA#9 not needing magnum primers might be true for my lot.

Now the question remains, what do I do with my 1000 CCI 550s? I heard AA#9 downloads well for .357 Magnums.

 

[mtgianni]

AA9, IME, downloads well 5% when you are heavier than 160 gr. It needs a heavy bullet to burn properly. All mine is older, so it isn't St Marks but Australian manufacture.

 

[Yendor357]

Pz, if I remember to do it, tomorrow, I’ll recreate your load using an XTP 158. I’ll chrono it for you.
I’ll use my 4 inch 686. That will give you some idea of how fast they’re going.

Then I’ll re-do it with magnum primers.

I’ll bet you’ll be ok with mag primers. I’ll let you know.

 

[TheTinMan]

So, I looked around and found out that Speer has the same load (with Speer bullets) calling for 12.3-13.7 grs of AA#9, but with a CCI 500 primer in .357 Mag for 158 grain JHP bullets.

I used 12.6 grs with CCI 500s, loaded to 1.580” OAL in my once fired PMC cases, Zero Bullet 158 gr JHPs, shot in my 4 inch Model 66-3.

The result? The damn cases tumble out the moment I tip the cylinder upside down. Recoil impulse felt softer, basically the same accuracy at 10 yards. The cases still in my cylinder only require a slight push of the ejector rod to come dropping out. I’m talking the same amount of pressure needed to run the ejector rod when the cylinder is empty.

Guess the whole thing about AA#9 not needing magnum primers might be true for my lot.

Now the question remains, what do I do with my 1000 CCI 550s? I heard AA#9 downloads well for .357 Magnums.

Interesting. I was going to type “all of my data shows small pistol magnum primers for AA #9” but checked and that’s not correct. 2003 Accurate Arms manual shows CCi 500s with a starting load of 13.5 grains under a 158 grain XTP bullet with a COAL of 1.58”. Velocity shown on the Hodgdon site now shows much lower velocities out of a 10” barrel vs. 8” for the 2003 data.