On my 6BR I'm at 500 rounds now and I've had to reduce the charge several times. After initial load development I was shooting 29.8 in a good node. After stepping down .2 and .2 again (because of hard bolt lift) I shot 29.4 this morning and got hard bolt lift and swiping. My accuracy is still great. Initial load was developed at 50 deg and today way 60. 107SMK Varget BR4. I don't have a chono.
Barrel speeds up, pressure rises?
- Thread starter mike a
- Start date
Magnetospeed sporter, love it!
It dosen't have all the functions of the v3, but it does what I need it to do.
Ran it simultaneously with an ohler 3 screen,
From muzzle we had 3fps difference from muzzle to 15' away.
swd
Silver $$ Contributor
Lab Radar but my friends with Magneto Speed’s like them too.
Keith Glasscock
Gold $$ Contributor
You have just about a perfect round count for a good carbon ring. Do you have access to a borescope?
I'd say your brass over length or you have quite the jam on the seating depth. You could also have a bad carbon ring. Do you know your touch measurement? Do you know your chamber length? And do you clean the carbon ring?
I didn't ask what length you're trimming to. I asked if you know your chamber length. You can measure chamber with a chamber length guage or if you have a print of your reamer that will tell you what your chamber length is. How did you measure that jam? I just recently had a friend say he was jamming .005" and after we found actual touch it was .029" jam!! How did you clean carbon ring? Not here to beat you up but to help.
This is a Savage prefit Shilen Select Match 1/8. I don't know chamber length. I found "touch" by using stripped bolt until I could just see land marks on the bullet. I us a Wilson seater and I just turned it in .005. I installed this barrel using go and no go gauges and have it close. The stripped bolt close free on a go but not even close to close on no go. I use Butches and a bronze brush. I also use iosso but not yet. Guess I'll have to get a borescope too. Damn won't be shooting much!
Last edited:
CaptainMal
Silver $$ Contributor
Actually blew primers out because of carbon fouling. Been a while but that sure was an eye-opener. Target, Rem 15 and H4895 are notorious for carbon build-up in all the 6 BR variations. Mine built, got hard and no amount of cleaning I knew of at the time worked. Had to replace that barrel and learned a proper cleaning technique from the whole experience.
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.
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.
+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.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.