.357Mag reloading questions

[zguy]

Hi Everyone,

Looking to reload 357mag and .38spl
I have MS200 propellent and small pistol primers, which i believe is acceptable for .38spl.

As for .357mag, it would seem that the only available local powder that is available is S265.
Can anyone confirm if magnum primers for this powder is needed, or if standard primers are suitable.

[Ds J]

MS200 and SPP work well with .38Spl. Please check the reloading tables if you shoot a snubbie or small frame revolver - they have special reduced loads to protect the frame of the revolver.

Please be aware of the danger (possibility) of double charges, especially with MS 200, simply because the charges are small enough that two charges fit into the case. As a precaution, I always throw a double charge when reloading for handguns, and keep it aside to check the other loads.

Also: please read up on flash over (detonation) which can happen in loads with small amounts of powder. If memory serves correct there is a great discussion on this on this forum. The chance of it happening in .38Spl is said to be extremely small but I still find it good to have knowledge on the subject. Some reloaders advise the use of filling (paper/dacron) in cases when reloading very light loads - I did it with good results. I also read reports which advised against it.

There is a catch with 357Mag, but I cannot remember exactly what it was. It has to do with bullet weight and barrel length. S265 works better with 18" carbine barrels, but not so good with revolver hunting loads?

MP200 works very well with 357Mag, but is generally out of stock.

I would not use MS200 in 357 Mag, rather get an imported brand.

Also: remember to crimp the bullets, otherwise recoil kicks them out - it has happened to me.

[big5ifty]

Avoid MS200 when the case fill is very low. This will happen in 38 and 357. The chance of a SEE with less than 50% case fill is not worth the risk.

Somchem gives load data for 38 and 357 using MS200, it does not mean the powder is actually suitable for that application.

Rather use MP200 in the revolvers, and leave the MS200 for 9mm and smaller cartridges.

[Treeman]

Yes, when loading sub sonic for rifles the MS at low case fill was not a well behaved child. Velocity jumps of 160 fps at 10 - 12 gr loads can be unsettling. This was not the case with MP200

[zguy]

Thank you Ds, big5 and Treeman.

A lot of good info.

[janfred]

Just for clarity sake, SEE has never been replicated. Only reported by people; usually when using reduced charges of slow powder. I do not think MS200 is a slow powder. You will definitely have eratic ignition and velocity shifts.

Clear as mud, right?

[Ds J]

Just for clarity sake, SEE has never been replicated. Only reported by people; usually when using reduced charges of slow powder. I do not think MS200 is a slow powder. You will definitely have eratic ignition and velocity shifts.

Clear as mud, right?

This explains a lot! Thanks so much.

[Treeman]

Just for clarity sake, SEE has never been replicated. Only reported by people; usually when using reduced charges of slow powder. I do not think MS200 is a slow powder. You will definitely have eratic ignition and velocity shifts.
Clear as mud, right?

******************************
Clear as mud sums it up, been reading loading 35 years and stink that I only understand that I do not understand.

[big5ifty]

Just for clarity sake, SEE has never been replicated. Only reported by people; usually when using reduced charges of slow powder.

In conversation once to a Glock retailer, he was going hunting with a Glock 20 and was concerned about pressure. I gave my opinion on SEE in pistols, that it was not due to too much powder but too little. When we met again, he told me about his experiment, he filled the case with MS200 under his hunting bullet in the G20, and there was no failure.

There is a type of SEE that occurs in rifles, where the barrel has split either in the middle or at the end, it is due to a too slow powder. The initial ignition burns a smaller part of the powder, and pushes the rest down the barrel. The larger part then ignites in the barrel, and of course a rifled barrel is not rated to the pressure of a chamber, especially in hunting rifles, so it bursts.

Where a rifle bursts open at the chamber, that is possibly the same SEE as occurs in pistols - too much air in the case with a too fast powder. Excluding the case of high pressure loads of smokeless powder in black powder guns.

[big5ifty]

What is not generally understood is that it is not safe to load to below the minimum level of the load manual.

Everyone understands that to go over is not safe, but not enough about the risk of an under-charge.

[oafpatroll]

Re the low case fill with fast powder, using S121 and Titegroup in .38 and .357 with charges at or below about half way up published loads I had disconcertingly large velocity spreads. Changing to Vectan 9.5 at around the same target velocities tightened the ranges right up.     

[janfred]

A lot of people much smarter than me have tried to replicate SEE and failed.

Using low loads of a fast powder in a pistol case it is very easy to double-charge said case. So, the running theory is that exploding pistols are usually due to wrong powder, a double charge or bore obstruction.

[oafpatroll]

A lot of people much smarter than me have tried to replicate SEE and failed.

Using low loads of a fast powder in a pistol case it is very easy to double-charge said case. So, the running theory is that exploding pistols are usually due to wrong powder, a double charge or bore obstruction.

A few years back when trying to talk myself out of pursuing low velocity cast loads for my 270 Win I went down a rabbit hole of trying to find reference to a proven SEE occurrence. Couldn't find one. Lots of compelling arguments based on the theory but nothing definitive.