Need help with diagnosis - 357 Blowback

[Muffin Man]

Hi all,

I’ve been getting blowbacks to the left side of my face from shooting 357 magnums. I’ve had to pull out two tiny shrapnel pieces from my face with tweezers yesterday. I need help figuring out if the issue is from my guns or ammo. Here are the clues:

- Ammo in all instances: PMC Bronze .357 magnum
- Happened using new S&W 686+ 6”
- Happened using new S&W carry comp 19 2.5”
- All cylinder holes appear to line up perfectly with barrel.
- I notice debris (maybe gun powder) inside cylinder after shooting. Do I need to clean it before shooting next rounds?

Please let me know if you have any questions that could help with the diagnosis. Thank you.

 

[ameridaddy]

Are you shooting very heavy bullets, and lots of full power ammo? If so, I suspect you have a timing problem. It's a dynamic thing, and not obvious checking static barrel-cylinder alignment.
Both my model 29's used to do that after about 6 months of max power loads shooting single action long range pistol metal silhouettes. It was even worse in double action.
The cure was for my smith to retime the guns, which for me was required about every ~ 500-1,000 rounds.

 

[Protocall_Design]

I would do a retime and make the forcing cone slightly larger. Some forcing cones are not cut large enough at the factory, some are not cut at all.

 

[Nightowl]

There are about 3 things, in my experience that would cause/contribute to to brass shavings in the face. The primary is the chamber and the barrel do not line up upon firing, thus shaving off bits of jacket. Contributing factors are large barrel to cylinder gap, allowing debris to get loose and the forcing cone not being cut to allow the bullet to enter the barrel. My experience with new guns, very limited experience, I must adds, is that they are overtimed, pushing the cylinder too far around, so that the chamber in misaligned with the barrel. Others may have a different experience. I have some of my older guns with inconsistant ratchet cuts, so that some chambers would overtime and one or more would not carry up, so more work to correct.

1. Check for endshake
2. Check barrel cylider gap. It should be between .004 and .10 max.
3. Check timing by holding frame in left hand and grip in right hand and
using right thumb, draw the hammer back until all the way to single
action engagement and noting when the cylinder stop engages. If the
cylinder stop does not pop up when the hammer is all the way back,
then the chamber and barrel will not be alighned at ignition. If it
pops up way early, then the hand may be pushing the cylinder out of
alighment with the barrel.
4. Check forcing cone on the back of the barrel to see that there is a
flare giving the bullet a little leeway entering the forcing cone.

Maybe the best option is just to contact S&W Customer Service and explain the problem and let them find the answer!

 

[AudieMurphy]

try pointing the gun the other way

 

[stansdds]

I think it is wise to check your revolvers to be sure there is not a problem with them, but since you stated the issue happens in two revolvers with the same ammo, I'm leaning towards it being an ammo problem.

 

[-BTM-]

Are the fired cases dirty? Where is the debris you mentioned, in the throat or in the chamber where the brass fits?

 

[daveboy]

I notice debris (maybe gun powder) inside cylinder after shooting. Do I need to clean it before shooting next rounds?

That is the first thing I would do. Start with a clean gun. Ensure that the forcing cone and barrel are clean with no build-up of lead/copper. Second thing I would do is try a different brand of ammo.

 

[BoulderTroll]

I think it is wise to check your revolvers to be sure there is not a problem with them, but since you stated the issue happens in two revolvers with the same ammo, I'm leaning towards it being an ammo problem.

Agree 100%. If two new revolvers are doing the same thing with the same ammo, your very first step should be to try different ammo.

 

[BrBa]

Hi all,

I’ve been getting blowbacks to the left side of my face from shooting 357 magnums. I’ve had to pull out two tiny shrapnel pieces from my face with tweezers yesterday.

- Ammo in all instances: PMC Bronze .357 magnum

Just curious, was the shrapnel that hit you in the face lead or copper jacket? Was it 125 gr JHP, 158 gr JSP, or something else? Did it seem underpowered or was there a lot of recoil? Did the cases extract easily?

 

[Muffin Man]

Thank you all for your thoughts. To answer some of your questions:

- the ammo I used is a 158 grain JSP from PMC Bronze
- the shrapnel in my face looked like either gun powder or dark brass pieces. Small chance it was lead.
- the debris was in the cylinder chamber. They looked like dark sand.

I’m planning to shoot it again tomorrow, but clean the cylinder after each use. If I don’t get shot in the face, it’s the ammo. If I do get shot in the face, I’ll call smith and wesson. I wish I didn’t have to use my face to diagnose this issue.

 

[Jim Watson]

Assuming you haven't broken anything, my first step would be to change ammo.

 

[rwsmith]

TRY ANOTHER AMMO......

Thank you all for your thoughts. To answer some of your questions:

- the ammo I used is a 158 grain JSP from PMC Bronze
- the shrapnel in my face looked like either gun powder or dark brass pieces. Small chance it was lead.
- the debris was in the cylinder chamber. They looked like dark sand.

I’m planning to shoot it again tomorrow, but clean the cylinder after each use. If I don’t get shot in the face, it’s the ammo. If I do get shot in the face, I’ll call smith and wesson. I wish I didn’t have to use my face to diagnose this issue.

...before you repeat using the PMC ammo!!!! It MIGHT avoid you getting your face shot. If I were to shoot the PMC again, I would put something in front of my face that would catch any flecks that head that way (pasteboard??)

 

[Bullet Bob]

Were you shooting from a bench rest, or offhand? Some .357 ammo is known to be a bit "spitty". If it was from a bench, try shooting the same way using your other hand, and see if the other side of your face is struck. If so, probably the ammo.

I remember the late Dick Metcalf testing a dozen or so different .357's from a bench many years ago, and resorting to wearing one of those clear plastic faceshields for the testing because of that problem.

All the experts have given good advice, thought I'd throw in my completely amateur suggestion. Good luck!

 

[SWFan27]

PMC is dirty and cheap ammo. I doubt that both of your revolvers have the same timing issue. You are probably getting crud building up from the ammo that eventually gets cleared and can hit you when it does blow out. I have had it happen using Magtech 357 Mag. And 22LR ammo is very dirty and it happens periodically when shooting my Model 617 revolver.

 

[BrBa]

- the shrapnel in my face looked like either gun powder or dark brass pieces. Small chance it was lead.
- the debris was in the cylinder chamber. They looked like dark sand.

There should not be any debris in the cylinder. What you're describing is unburned powder. The powder was likely contaminated in some way. If you don't reload, I would consider tossing it. I've had similar problems with Magtech. It's just not worth the hassle.

 

[Grayfox]

Some years back a friend was shooting a Korth .357 in the lane next to me. I felt a sting on my arm and realized I was bleeding a little. I dug a 1/4" piece of jacket material out of my arm.
The ammo was PMC.
Change ammo first.

 

[Narragansett]

I am no expert here, but I would change the ammo, AND check the forcing cones in both guns.

Of course pics of the cones would help a lot with offered opinions

 

[-BTM-]

The ammo might actually be under-charged if it not sealing the chamber, you might be getting gas and fouling out the back.

 

[Muley Gil]

Thank you all for your thoughts. To answer some of your questions:

- the ammo I used is a 158 grain JSP from PMC Bronze
- the shrapnel in my face looked like either gun powder or dark brass pieces. Small chance it was lead.
- the debris was in the cylinder chamber. They looked like dark sand.

I’m planning to shoot it again tomorrow, but clean the cylinder after each use. If I don’t get shot in the face, it’s the ammo. If I do get shot in the face, I’ll call smith and wesson. I wish I didn’t have to use my face to diagnose this issue.

Get somebody you don't like to shoot it!