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6br break-in/fire forming/load

Kevin1990

So I switched from a 6cm that I didn't really like to a 6br. Fairly new to reloading, and shooting anything for precision.

Figured I'd fireform my Lapua brass with old bullets I had left over from my 6cm. I shot 103eldx, 105bthp,107smk,and 108eldm.

Shot 100 rounds. I loaded them from 29.7-30.2 with varget, and all 5 shot groups were .5 or less. (Surprised, but the Hornady 105bthp shot the best.)

Questions:
How many rounds should it take to break in a 6br barrel? Should I have started load development already or should I continue to break it in?

How many times do you usually fire brass before it's fireformed. With a comparator my virgin brass was 1.1600, and after one firing it's 1.1640. going to clean the barrel tomorrow, and check the brass tomorrow and see how the bolt feels.

Thanks fellas
 
Im not sure what you refer to as break in but my barrels usually take around 90 to 130 rounds to settle down or to finish speeding up. I usually fireform 100 or so pieces of brass and then start with serious load development. Your brass will be completely fireformed after 2 firings but they will be good to go now after one firing. Set you sizing DIE up for that 1.1640 so that you set form them back to that size after the next firing, that should get you close to 1 thou shoulder setback after sizing them.
 
Kevin1990 said:
So I switched from a 6cm that I didn't really like to a 6br. Fairly new to reloading, and shooting anything for precision.

Figured I'd fireform my Lapua brass with old bullets I had left over from my 6cm. I shot 103eldx, 105bthp,107smk,and 108eldm.

Shot 100 rounds. I loaded them from 29.7-30.2 with varget, and all 5 shot groups were .5 or less. (Surprised, but the Hornady 105bthp shot the best.)

Questions:
How many rounds should it take to break in a 6br barrel? Should I have started load development already or should I continue to break it in?

How many times do you usually fire brass before it's fireformed. With a comparator my virgin brass was 1.1600, and after one firing it's 1.1640. going to clean the barrel tomorrow, and check the brass tomorrow and see how the bolt feels.

Thanks fellas
Click to expand...
Your brass grew .040 ? Or you missing a decimal point
 
mudduck said:
.004 thousands would be 1.604 not 1.640. You’re good at 1.604. Set sizer up for 1.6025+/- and you should be good
Click to expand...
I Think you missed the first digit after the decimal. He stated "virgin brass was 1.1600" and you correctly identified the 0.004" growth, resulting in an after-fired length of 1.164"
 
Just size the neck don't have to bump the shoulder until after the second firing. Shoulder gets blown out to match the chamber on the second or third firing. If you can anneal after the first firing that would be good. Start load development after 1st firing or brass breakin as the Virgin brass is slightly smaller.
 
1sickPuppy said:
Just size the neck don't have to bump the shoulder until after the second firing. Shoulder gets blown out to match the chamber on the second or third firing. If you can anneal after the first firing that would be good. Start load development after 1st firing or brass breakin as the Virgin brass is slightly smaller.
Click to expand...
Awesome! I kind of did that. I decapped, and set my FL die to just rezise just the neck. However, I forgot to annea before that. I might do it anyway before I seat the bullets?
 
So with the firing pin and ejector removed, the brass that is 1.1640 will not freely close. When I tap it, it moves, but doesn't fully close without me persuading it. I bumped it back to 1.1630 and it closed freely, and at 1.1620 it didn't even feel like brass was even in it. So I think I'm all fireformed?


Last question. Would you bump it to 1.1630 or 1.1620?

Thanks for all the help everyone.
 
Kevin1990 said:
So with the firing pin and ejector removed, the brass that is 1.1640 will not freely close. When I tap it, it moves, but doesn't fully close without me persuading it. I bumped it back to 1.1630 and it closed freely, and at 1.1620 it didn't even feel like brass was even in it. So I think I'm all fireformed?


Last question. Would you bump it to 1.1630 or 1.1620?

Thanks for all the help everyone.
Click to expand...
Bump the 1.164 back .001” at a time. Take the bolt out, insert the case with Your finger. Point the muzzle at the ceiling. If the case doesn’t fall out, and has to be pushed out with a rod, keep going. When the case falls out, You are at fire form minus .001”. You can use this same procedure with a loaded case to find “touch” of the lands.

As far as “ when are You fully fire formed “, You can accomplish it on the first shot. Just load them suckers hot. But Your brass will suffer for it. For brass life, it’s best to do it in 2 steps. And barrel break in is also subjective. It’s done when Your satisfied that it’s done. Some shooters do all this stuff in Matches. And gain what ever information can be gained along the way. Or we could just shoot into the berm 200 times and learn nothing.

The answers to Your questions depends a lot on what kind of shooting You intend to do and what results You expect.

All of this is JUST MY OPINION, but then, what else could it ever be ???
 
Rat Rifle said:
Bump the 1.164 back .001” at a time. Take the bolt out, insert the case with Your finger. Point the muzzle at the ceiling. If the case doesn’t fall out, and has to be pushed out with a rod, keep going. When the case falls out, You are at fire form minus .001”. You can use this same procedure with a loaded case to find “touch” of the lands.

As far as “ when are You fully fire formed “, You can accomplish it on the first shot. Just load them suckers hot. But Your brass will suffer for it. For brass life, it’s best to do it in 2 steps. And barrel break in is also subjective. It’s done when Your satisfied that it’s done. Some shooters do all this stuff in Matches. And gain what ever information can be gained along the way. Or we could just shoot into the berm 200 times and learn nothing.

The answers to Your questions depends a lot on what kind of shooting You intend to do and what results You expect.

All of this is JUST MY OPINION, but then, what else could it ever be ???
Click to expand...
Great info! Really appreciate it. So I tried this with the 1.164 and it kind of stuck kind of didn't. I loaded one round of 1x fired brass. Went out back and fired it. Came in, and it measured 1.1645-1.1650. that one needed to be pushed out with a rod. Bumped back to 1.1630 and the case fell out and wouldn't stick.

Also, I like that idea with a loaded round to touch the lands.

Thanks!
 
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