Barrel speeds up, pressure rises?

[Bc'z]

Where does the carbon ring deposit land itself exactly. My 22 Dasher was doing the speed increase. 20 FPS per shot.

In the throat jus before and into the lands.
Short brass and jumps aid in creating this
dreadful barrel disease .

 

[Texas10]

I recommend you skip the bore scope expense and get a cheap, $35 endoscope camera. It'll plainly show carbon buildup in the neck of the chamber, and verify your cleaning processes. Go to Amazon to find them.

To remove carbon in the chamber neck and throat, I use a bronze brush on a short piece of cleaning rod and battery operated drill. Use a chamber mop and soak the area for a while with your favorite cleaner, then spin the brush in the chamber. Use the camera to verify you are getting at the problem area, then patch it out.

My camera will blue tooth to my phone, enabling me to take pics if I want.

A look down the muzzle end with the camera after cleaning will show any copper left in the cleaning process.

 

[Richard Coody]

You have just about a perfect round count for a good carbon ring. Do you have access to a borescope?

+1

What is your cleaning method? Carbon remover? C4 works great. Copper? I like boretech eliminator.

Probably time to short stroke that throat with losso. A lyman borescope will tell you for sure.

I use a parker hale jag with a large patch wrapped around it soaked with c4 and coated with losso. Short stroke the throat and first 8 or 10 inches of barrel.

It's funny because the whole concept of the "carbon ring" is apparently a unknown to many shooters, and when you mention it to some, some look at you like you are on a different planet. In the past month I had two customers who had constant pressure problems and thought there was something wrong with their barrel - - there was, there was a carbon ring in each case and it was so bad it was constricting the throat area so that when I pulled a cleaning rod backwards through the bore with a tight patch on it, I could feel the back pressure increase significantly right before it hit the chamber. I used JB on a big patch wrapped around an undersized bore brush and worked the throat area and that got rid of it in each case. Test firing loads that were blowing out primer pockets before proved to be now fine after getting rid of the "carbon ring". I looked at one "carbon ring" before the JB treatment and it had bits of copper jacket embedded in it just like L.E. Hanson notes above.

 

[C.E.Smith043]

Once you start using a chronograph you’ll wonder how you got along without one..

I completely agree, yet i always get hand fulls of shooters whom claim otherwise

 

[carlsbad]

what is the neck clearance on your chamber? I had a similar/worse episode and the same solutions were suggested here. I finally concluded that I didn't have enough neck clearance so I was getting some neck tension impact from the chamber. Normal clearance is .005 to .008 and I was running tighter, about .002 (machinists and engineers often mistakenly think tighter clearances are always better).

 

[Liven The Dream]

Same Lot of Varget ?? All Varget is equal ...

 

[mike a]

Update. So you guys were right. Spent the morning scrubbing, shot this evening. 30.0 Varget, .010 jump. No pressure. 5 shots, 100 yards prone bipod. 6BR is like cheating.