67-1 sticky extraction

[Fkimble]

I've got a 67-1, my load consist of 158SWC(.358) MBC's, either hardness, 3.5 gr Bullseye. No barrel leading but after one or 2 cylinders full, I start having a chamber or two in which crud builds up requiring pushing the round extra hard to get it completely seated so I can close the cylinder and have it rotate. Was thinking about using it in a revolver match but until I figure out what's going on I would never make it through a stage with a couple reloads. I also tried Dardas bullets but same problem. It's not lead, it appears to just be powder fouling in the forward 1/4 of the chambers. This is a normal target load so not sure whats going on. Any thoughts from the collective wisdom here?

 

[Jellybean]

Make sure your cylinder is completely clean of all fouling and check for any pitting. It sounds as though something is causing the crud to build up that shouldn't be there.

 

[Titegroups]

The first thing to do is find out what the crud is, lead, powder residue?

 

[Fkimble]

It's not lead. Looks like combustion generated. You can see a kinda swirl pattern sometimes. I cleaned it real good and ran 3 cylinder fulls thru it with Bayou bullets. They don't produce any problem in my 357's. Same kinda smokey buildup in the front 1/3 of the chamber. I did notice the ammo seems to have lot of extra room in the chamber. Wondering if this excess room is allowing more blowback than normal. Can stick a round in halfway and wiggley it quite a bit. Will try to measure the chamber. No sign of pitting either.

 

[Titegroups]

Maybe mark the chambers with a sharpie and see if it's always the same ones.

 

[dardascastbullets]

It's not lead. Looks like combustion generated. You can see a kinda swirl pattern sometimes. I cleaned it real good and ran 3 cylinder fulls thru it with Bayou bullets. They don't produce any problem in my 357's. Same kinda smokey buildup in the front 1/3 of the chamber. I did notice the ammo seems to have lot of extra room in the chamber. Wondering if this excess room is allowing more blowback than normal. Can stick a round in halfway and wiggley it quite a bit. Will try to measure the chamber. No sign of pitting either.

You aren't by chance using a factory crimp die are you? What powder are you using? What are the ID's of the cylinder throats? And what is the slugged diameter of the bore? There are other questions I have but these need to be answered to start forming a resolution.

 

[sza]

My guess is that your load is generating too little pressure to completely seal the cases against the chamber walls.

Are the cases sooty near the mouth after firing? Do you get any soot or crud buildup on the recoil shield?