Barrel setback question.........

ultramagmed

ultramagmed

JKM
I was just doing some measuring for seating depth on my 6.5-06. I have 775rounds through it already (3 months....wow) and my measurements show that I've shot somewhere between .040-.045 out of the throat compared to the gage I made from the barrel stub. Accuracy is falling off, but that seems a little excess erosion for that many rounds to me, or does that sound about right? I've been shooting IMR 4350 and I have heard that it is a little hard on throats (not sure if that's true or not).

My next question is how much to cut off the barrel? Do I pre-drill and bore again or just ream this time? I know how to pick up the thread and all that stuff, so I think I'm good there. This is my first setback so any and all opinions are welcomed.

Thanks in advance,
Med.
 
Actually you don't have to pick up the thread, just make a longer thread relief. I would study it closely with a borescope, but would go about .150.
Butch
 
Just my opinion but if the throat has moved that much and what you see seems resonable. Then the finish has deteriorated down the barrel. I would cut the tenon off and start over just like it was a new blank. Then swap ends and cut a new crown.

Dave
 
Set Back

I set a lot of my own barrels, but they are all Competition 6PPC Barrels. I can hardly notice the wear, it's just something I do.

The main thing in setting up the barrel for a set-back is getting it back in the lathe exactly the same way it was when chambered. Since you did it the first time, you probably know how.

If you just want to set it back a thread or so, I would indicate the chamber and let the reamer follow the originol hole. In all honesty, that is what it is going to do anyway. Considerring the small amount of taper involved in the chamber, if you try to re-bore, or do any other similiar thing, you just do not have enough metal to play with unless you cut a lot of length off, say about 1/2 the chamber bodies length.

As Dave said, if you go that far, just chop most of the chamber off and treat it like a new blank. An 0-6 is a pretty long case, you have to decide whether loosing that much barrel, (ie, velocity), is worth gaining a little accuracy.........jackie
 
ultramagmed said:
I was just doing some measuring for seating depth on my 6.5-06. I have 775rounds through it already (3 months....wow) and my measurements show that I've shot somewhere between .040-.045 out of the throat compared to the gage I made from the barrel stub. Accuracy is falling off, but that seems a little excess erosion for that many rounds to me, or does that sound about right? I've been shooting IMR 4350 and I have heard that it is a little hard on throats (not sure if that's true or not).

My next question is how much to cut off the barrel? Do I pre-drill and bore again or just ream this time? I know how to pick up the thread and all that stuff, so I think I'm good there. This is my first setback so any and all opinions are welcomed.

Thanks in advance,
Med.
Click to expand...

I can't remember the exact numbers, but Bob Pastor told me that his 6.5-06 bbls taper off after 800 rounds? I think, and he said the gravy is 200-600....
he felt. I have an email somewhere..I'll try to find.
 
Have you chased the rifling and increased the load trying to maintain accuracy?

The wear is normal for a large "hot" case. Neck it down to 6mm and it's even worse.
 
One other thing

You did not say if this was a Stainless Steel Barrel, or Chrome Moly.

The burned portion of a Stainless Barrel isn't too bad on the cutting edge. But Chrome Moly can develop sort of a 'glaze', (for lack of a better word), that can be a little difficult on a fine cutting edge if you do not run the reamer at a rather slow speed.

Just be carefull. The cutting edge of a HS Steel Reamer is a fragil animal. Use a big dose of oil and a slow speed untill you initially break through that very thin area.........jackie
 
Butch,

I don't have a bore scope, and don't know anyone around here who does but, .150 sounds easy enough. I can always go deeper if I need Like Dave said and I have eternal tinkeritis anyway.

Ben,

Thanks I'll take any 6.5-06 specific info you may have. I have really enjoyed this cartridge.

Dennis,

I have been chasing the lands with seating depth but, haven't increased the charge. Maybe I'll try that first.

Jackie,

Length is definitely an issue, it's only 26" right now and it is a stainless tube. I wasn't sure if 28" long and 1.200" would be too much weight for my Remington action but, when I re-barrel this spring I'm going to cut it 28-29", I can always cut it down if needed.

Thanks for all the great information guys,
Med.
 
That was a really good thread.
Thanks for the good posts.
Ted
 
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