Well it finally happened.
I screwed up reloading.

I loaded some 158gr lswc .357's with autocomp.

I always get charges of +/- .05 gr or better with this powder and have been using it for a while. I really don't think it was my charge.

I used a standard primer instead of a magnum. (It called for a magnum)

Anyway, i worked my way up and had 1 very hot load, but I brushed it aside and thought somehow I screwed up and it was just that round.
I safely got all the way up to the max charge with no pressure signs except the 1 round that was a fairly low charge.

So I left thinking I had a good load but had somehow screwed up on that 1 round.

I loaded 50 more that night at the max and shot them the next day.

On round 3 it happened again. It locked up my gun.
I smacked it open and had to hammer the brass out.

The cylinder closes and everything functions fine, but the chamber is bulged and binds on the top strap If I try to open it with that chamber at the top.

So I learned a BIG lesson about making assumptions and got very lucky I didn't blow my hand off.

I think the real cause was inconsistent powder burn. II think some rounds were hotter depending on where the powder rested in the case (it was only about 1/4 of the way full.) I feel a magnum primer would have produced more consistent ignition and shown pressure signs at some point indicating when to stop.

I don't believe for a second I overcharged 2 rounds in 2 days.




So is my gun likely a lost cause?  It's a model 19-4 4" in need of a reblue. I can't just buy a cylinder off ebay and expect it to fit can I?  I expect a gunsmith would charge me more than what it would cost to replace.

You can probably find a cylinder.  

If I was going to test loads, especially wadcutters loaded near the max, I’d find a M28 or a L frame.  K frames don’t like .357s.   They’re much happier with .38s.

This is why I never use anything close to a max load! In a semi I run the load up from mid range ( so for instance if the load manual says min is 4 and max is 6 I load at 5) if the gun runs with acceptable accuracy stop
Right there.
If for any reason I need a near max load ( I never get any closer than 1/2 grain below max ever- too many variables with brass strength seating depth and so on) I will assemble those by weighing each charge individually and seating bullets one at a time on verified charges only.
Finally when any and I mean any doubt exists pull down the loaded rounds and start over

You had an overload or a double load.You didn't bulge a cylinder by using a standard primer.

I had to go to the max load with my .380's just to get my g42 to cycle

I won't be doing in the future again unless I have a good reason to.

In this case I just got stupid and my cockiness bit me.
I should have just stuck with the lower pressure 231 load. Especially since it's not a self defense or hunting load.

I don't think the primer it's self did it. I think it's inability to get a consistent burn fooled me into thinking the load was safe when in reality some were burning at a different rate than others depending on the powder position in the case.

I always check 10 charges on my progressive before I start loading and check every 10th charge while loading and I've never, in 8 years seen an overcharge. Especially not 2 of them 2 days apart.

I think those 2 just got a fuller burn than the rest.

I've seen enough reports of 'detonations' / damage from loads like this, that I'm very leery of any load that fill such a small portion of the case volume.
Visualize filling a case 1/4 of the way, turn on it's side (as it would be in the cylinder/chamber) and notice that the powder is all below the flashhole .. it would allow the flash from the primer to hit the entire surface of the powder, rather than the 'base' of the powder.
Rather than burning the powder from the base up, it flashes the whole of the powder at once... burn rate is much faster and pressure spike is much faster/intense as a result.

There is a reason old .45/70 loads that used little amounts of powder called for a filler of cream of wheat or pillow fluff.

I love Autocomp... it's a great 9mm powder.  I'd look for something that gives similar velocity with more 'volume' for .38/357 myself.

In the end, you could buy a cylinder and have it fit by a good gunsmith.  Heck... call S&W, they might be able to help you out as well.   I'd be concerned about frame integrity if that round bulged the cylinder, it may have damaged the frame as well.

I think the frame is ok.
The cylinder will rotate fine, it just doesn't want to open or close on that chamber because that will cause it to rub on the way in and out

See if you can find a stripped cylinder.  If the star extractor fits. The timing should still be good with the original hand

Personally I would send it to the factory.    Have it factory reblued and tuned while it's there.    The should also have the ability to check out the frame dimensions.    You may not get that level of knowledge and capability in an average gunsmith.    There is a wide disparity in gunsmiths.   Some are specialists.  Revolver specialists are getting less common in areas.    I used to know a crackerjack PD armorer whose prime was in the revolver days.   Unfortunately he passed on.

Many schooled gunsmiths get basics on revolver but I doubt many are in practice enough with wheel guns to be comfortable beyond "it works again".