Crud Ring with zero powder

[MountainDevil54]

So when i was testing out the Winchester W209 primers in the Wolf, I mainly wanted to see how bright and how long the flame was that came out the end of the barrel just by using a primer. After popping 6 primers i went to run a patch down the bore to remove the fouling and was shocked to see a crud ring forming 2" in front of the Breech plug just by using primers


That was interesting as i never would have thought that just a primer could start a crud ring. And WHY only in that spot so consistently?

Zero oil of any kind in the bore during this test.

[txhunter58]

Probably has to do with how the flame gets dispersed through the flame channel. With powder in place, it probably won't be an issue. When you passed a patch, was there a tight spot there, or was this cosmetic only and not a narrowing issue?

[lemoyne]

Maybe you are getting special treatment. Would a name change help?

[HuntAway]

Originally Posted by lemoyne

Maybe you are getting special treatment. Would a name change help?

HA

[7.62NATO]

Have you ever used T7 in that gun?

[MountainDevil54]

yeah a long time ago when i was testing pellets.

[arcticap]

I suspect that the primer material is some kind of a composition that's made from lead styphnate.
The pure form is a crystal that looks like a brown powder so I suspect that what is used in primers isn't pure.
So maybe that's what creates some of the residue.
And different companies have slightly different primer formulas that make a difference in the type and amount of residue.
The primers are mass produced while the primer material is in a liquid state that acts as a carrier for the active ingredient. So some of the impurities are probably necessary to make mass production possible.

http://en.wikipedia.org/wiki/Lead_styphnate

http://www.powerlabs.org/chemlabs/lead_styphnate.htm

14 second video:

http://www.youtube.com/watch?v=IGnTJqh55H0

[7.62NATO]

Fine, articap. But why would it form a specific crud ring with no load in the gun? Has to be sticking to an area of the barrel where a crud ring had formed before.

[sabotloader]

Originally Posted by 7.62NATO

Fine, articap. But why would it form a specific crud ring with no load in the gun? Has to be sticking to an area of the barrel where a crud ring had formed before.

I would believe it is a reaction with the oils that have been used in the bore. Especially if it were an oil based on real pertroleum or containg Teflon.

Even though the surface of the bore may have been cleaned with alchohol the pores of the metal still contain contaminates with can react with the heat of a primer as well as the heat of the load.

I wonder if he were to clean the bore with boiling water, which will case the pores in the metal to purge their contents then try the same experiment, what the results might be?

If the fouling were soft, I would believe that an additional problem will occur when shooting just primers, because primers are not clean.. and the debris build up will naturally occur around the nose of the breech plug where there is a ledge for the primer pressure to build back on to.