Carbon ring

[jlorenzo]

Teslong bore scopes' are not for the faint of heart, especially when using on factory barrels. I really would hate to do with out one now though..... Really good way to tell where your case length needs to be trimmed to also. Only advice I can give on the carbo fing is better to not let one get to far ahead of you lol...

As far as getting the case length right how many firings do you find it needs to get them all long enough to trim to the same size for your individual barrel? If you understand what I'm asking.

 

[D-4297]

My standard cleaning regime is to spend actually more time focused on the chamber neck area , than the barrel . I wet the area with C4 from a bottle with a tube , and insert a nylon brush on a long cleaning rod , attached to a drill . Run it a slow speed for a minute or so . Run the cleaning rod with dry patch . Repeat the process . Wrap dry patch on brush and run into chamber neck area . I have never seen a carbon ring in any of my barrels since doing this process . My thought is : If you don't let it get started , you don't have to deal with it later on . Now ; If I could just figure out how to get those light little carbon tracks out of the grooves ..

Regarding Case Length , I shoot a No Turn , .308 TR . The "Book" spec says to trim to 2.005" , but my last four boxes of Lapua came at 2.010" , and that has become my standard trim length since . Seems to require less trimming , like almost never , and believe it or not , the target has gotten more consistent , too .

 

[JMayo]

As far as getting the case length right how many firings do you find it needs to get them all long enough to trim to the same size for your individual barrel? If you understand what I'm asking.

Depends on the caliber. Some really change fast some change slower, some do not realty change at all.
I check it during 1st prep then after FF 3 firings it's worth looking at again.

i shoot calibers that don't change much. My 30br needed trimming in the very beginning just to fit. My 6bra & ppc have been made the same length.

 

[jlorenzo]

Depends on the caliber. Some really change fast some change slower, some do not realty change at all.
I check it during 1st prep then after FF 3 firings it's worth looking at again.

i shoot calibers that don't change much. My 30br needed trimming in the very beginning just to fit. My 6bra & ppc have been made the same length.

I ask because if my specific barrel needs cases with longer necks (than book trim length) to take up the spot where the carbon ring would form, that would mean they need to be fired multiple times to reach that length. In my experience they rarely all grow by the same amount. It would seem getting 100 pieces of brass all at a longer case length would be difficult. By the time theyve been fired enough times to reach optimum case length they already have a few firings on them also.

 

[Mike TackleBerry]

For my rifles I've been taking a bore mop and soaking it in solvent, Then I just cram it in there and let it soak for a few hours then come back with a bore diameter brass brush covered with a patch and put it in there and spin it around. Removes every ring I've ever had.

 

[divingin]

Regarding Case Length , I shoot a No Turn , .308 TR . The "Book" spec says to trim to 2.005" , but my last four boxes of Lapua came at 2.010" , and that has become my standard trim length since . Seems to require less trimming , like almost never , and believe it or not , the target has gotten more consistent , too .

The SAAMI spec for the chamber drawing puts it at 2.025" so that would be your max (without carbon ring.) AFAIK you can choose whatever length you want (within reason) as long as the length doesn't exceed the length of your chamber. Shorter will give you more growth length before you need to trim again. Longer will leave less room for carbon to deposit (maybe - depends on if the carbon deposits before the neck seals to the chamber.)

On the number of firings, I'd guess it depends on a bunch of variables such as: pressure you run your loads at, how much the body grows and gets resized, how much you set your shoulders back (as that drives neck growth to some degree), etc. I wouldn't worry too much about having a correct length, as it's kind of guesswork on what's "correct" anyway.

Edit: Maybe "ambiguous" would be a better word than "guesswork".

 

[JMayo]

I ask because if my specific barrel needs cases with longer necks (than book trim length) to take up the spot where the carbon ring would form, that would mean they need to be fired multiple times to reach that length. In my experience they rarely all grow by the same amount. It would seem getting 100 pieces of brass all at a longer case length would be difficult. By the time theyve been fired enough times to reach optimum case length they already have a few firings on them also.

I'm not following the necks getting to a certain spot in the bore. They are where they are. That's where the ring will form if left in cleaned.
My 6mm's are a noticable distance from Max length capable. My 30br was over and had to be trimmed.

 

[divingin]

I'm not following the necks getting to a certain spot in the bore. They are where they are. That's where the ring will form if left in cleaned.
My 6mm's are a noticable distance from Max length capable. My 30br was over and had to be trimmed.

How do you think the 30's got longer than max (assuming they were ever in-spec)?

Yes, they are where they are this time through, but they tend to lengthen with shoot-reload cycles (hence the need to trim.) If they didn't, very few people would have need for a trimmer.

 

[JMayo]

30's were too long to start with.
6's are not

Br wildcats do not grow much but they stack it on the inside neck sholder area aka "donut"