Setting back barrels

B

bob3700

Member
Group,

When you are setting a barrel back, do you cut the barrel to eliminate the old chamber completely?

It would seem that you would have to in order to make sure that the new throat area and chamber would be running true to each other.

If you leave any of the old chamber/throat in the bbl, will not the reamer just follow the old hole and if the bbl bore now curves, the throat and chamber will be misaligned?

This is on a 6mm BR cartridge.

Thanks for your thoughts.

Bob
 
If you have enough barrel diameter left after cutting off the entire chamber, and if you have sufficient length left, then this would certainly be best. But remember, depending on the old and new chambers dimensions it may not be necessary to remove all the chamber. To visualize this make a to-scale sketch of the old chamber then make a to-scale cutout of the new chamber then overlay the cutout over the sketch.
 
Jerry,

I have more than sufficient diameter and length. I am setting the barrel back on my 6mm BR. Same chamber, same reamer.

So, you start to put your indicator up in the bore where the new throat will be and find out that the bore is starting to curve and is no longer concentric with the old chamber. The reamer is just going to follow the old hole.

You can't bore the hole true to the new throat because the diameter of the case at the shoulder and the diameter of the base is too close to each other. Not enough meat to true things up.

So, it seems to me the only way is to cut the old chamber off and start new.

Thanks for your reply.

Bob
 
i guess it depends on how much throat wear you have. i believe jackie freshens up the throat by moving forward one thread(?). he does it at a very low round count.
its a question of how much the bore moves off from its current throat. in one thread forward not much movement, but if you move forward two inches...who knows.

mike in co
 
Mike,
I am actually moving forward about a full inch cutting off the threads on the tenion. This is an NRA Highpower 1K rifle so I want to move into good bbl material.

Went ahead and cut the chamber off up to the shoulder of the case. Drilled and then bored the hole true to the new throat location. Now the old chamber will be gone and the new should be true to the new throat location.

I keep putting the Interapid indicator in to check that the throat is still running true. Will let you know how it turns out.

Bob
 
I pulled the barrel off my 220 Swift AI tonight. I would have to set it back about 10 inches.

Not exactly on topic - I estimate 1500 rounds - PDogs are tough on barrels.
 
its not the dogs, it the caliber that is tuff on bbls.....

mike in co
kgcoker said:
I pulled the barrel off my 220 Swift AI tonight. I would have to set it back about 10 inches.

Not exactly on topic - I estimate 1500 rounds - PDogs are tough on barrels.
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