6BR strategy for breaking in new Lapua brass

[DB_23]

I have a new lot of Lapua BR brass to break in to shoot in a 6BR no turn chamber and want to get this fully formed. I am currently shooting 107 SMK. All my shooting is at the range, no competition.
I am looking for suggestions as to the best approach to getting the brass to fully formed while shooting?
I have been using GRT. Is there a target case pressure that is useful in getting this done.
1. Shoot the 107 SMK at slight jam and reduced load. (The 107's are pretty reasonably priced).
2. Shoot a lighter bullet with more powder for a couple of loadings.
I'm loading Varget powder.
For what it's worth, I have done quite a bit of reading regarding this but still looking for some advice.
Thanks

 

[Rat Rifle]

I have a new lot of Lapua BR brass to break in to shoot in a 6BR no turn chamber and want to get this fully formed. I am currently shooting 107 SMK. All my shooting is at the range, no competition.
I am looking for suggestions as to the best approach to getting the brass to fully formed while shooting?
I have been using GRT. Is there a target case pressure that is useful in getting this done.
1. Shoot the 107 SMK at slight jam and reduced load. (The 107's are pretty reasonably priced).
2. Shoot a lighter bullet with more powder for a couple of loadings.
I'm loading Varget powder.
For what it's worth, I have done quite a bit of reading regarding this but still looking for some advice.
Thanks

Don’t overthink it. You said Your not competing. For Your purposes, shoot the cheapest pills You can find, regardless of weight. At some point You My decide fire forming is not necessary for Your shooting purposes. Just My Opinion.

 

[urbanrifleman]

I doubt your groups will change from brand new brass if your neck tension is correct.

 

[HTSmith]

My thought (and it could be all wrong) is to go shoot seriously from the get go. I've seen matches won with new brass. Sierra 107's are dang good bullets in my opinion. In one of my barrels they outshot 3 different Bergers that I tried. Go a little light on powder on your first cycle (say 29.4 or so of Varget). After one firing cycle you'll need to readjust your seating depth (probably) and you can add a little more powder to see if there is higher node that you like. No need to waste components and barrel life. Have fun from the start. JMHO

Edited to say to run a mandrel into your new brass, as they typically come much to tight from the factory.

 

[Cory porter]

I loaded up new brass for a new barrel, shot it once then neck sized it shot it again and did it a 3ed time.

Sent the brass to Harrells and got a die made for that chamber. Best results I’ve had, FL sized every time since and couldn’t be happier

 

[swd]

107SMK’s in the lands to where the engraving marks are square tends to work very well. I’ve had some barrels shoot so well there, there was no point in doing any seating depth testing. And as Corey mentioned Harrells dies are awesome.

 

[Clancy]

Just do your normal load development, preferably with the bullet jammed. After it all once fired maybe do a little charge weight tweaking.

Don’t overthink it.

I usually provide a few pieces of my brass to the smith and have the chamber cut on the snug side. I’m one of those strange guys that won’t build a gun if I don’t have everything in hand though.

 

[rwj]

Some of the new lots of 6BR Norma brass from Lapua has been reported to have thicker neck walls than earlier lots. You may want to check the case neck OD of a loaded round and compare it to your chamber before heading to the range.

 

[NorCalMikie]

New brass, load and shoot. My guess? You will really be surprised at the accuracy of those thrown together loads.

 

[DB_23]

Some of the new lots of 6BR Norma brass from Lapua has been reported to have thicker neck walls than earlier lots. You may want to check the case neck OD of a loaded round and compare it to your chamber before heading to the range.

I'll double check that, thanks.

 

[Dolomite]

All good advice above. Go about 1-2 grains lower than your target load, hard jam the bullet should blow out the shoulder without affecting the base.

If it’s a new barrel it may take around 100 rounds to break in. Mine just kept speeding up and settled around 125 rounds.

If you have that much brass and don’t care much about preserving the brass load it up and shoot a mild load for 100 rounds.

Another controversial method is to lightly and I do mean lightly oil the brass so it doesn’t grip the chamber.

“I now jump my virgin br cases with the front 1/2 of the case lubricated to allow the brass to flow and resize in the chamber with out sliding back and smashing the bolt face.”

GRT was off for me, the FPS was lower than what I experienced. It works best with actual FPS data from your loads.

I loaded up new brass for a new barrel, shot it once then neck sized it shot it again and did it a 3ed time.

Sent the brass to Harrells and got a die made for that chamber. Best results I’ve had, FL sized every time since and couldn’t be happier

^^^this

 

[DB_23]

All good advice above. Go about 1-2 grains lower than your target load, hard jam the bullet should blow out the shoulder without affecting the base.

This is what I'm hoping to do. All good input above and thanks to everyone who chimed in. My skills probably don't measure up to any improvement in the fully formed brass but I can't help tinkering with the details.

 

[AlNyhus]

On new brass, I put a few drops of a very light lube (3 in 1, etc) on a patch and wipe each case with it before firing. It helps the brass conform to the chamber on that first 'whap'. -Al

 

[marchx]

I just sorted lapua brass and was shooting F-class match with 6BR using virgin brass earlier this year. placed in top 10. as somebody said, do not overthink the whole fireforming voodoo.

 

[Cfshooter]

I’m

I just sorted lapua brass and was shooting F-class match with 6BR using virgin brass earlier this year. placed in top 10. as somebody said, do not overthink the whole fireforming voodoo.

10/10, not too shabby . (I had too lol)

 

[coldboreshot]

Some may disagree but I run a .2435 mandrel through the virgin brass and resize with a bushing neck die, down .001 and do not re-mandrel with the standard one. It sets a nice seating pressure on the arbor press and shoots as normal. Because the brass is factory annealed, not much cold-working. SD only goes up a couple points compared to 5x brass (still single digit) but equalizes after a couple firings. Did this during a match...worked exceptionally well.

 

[DB_23]

Following up on my post. First, thanks for all the input. I loaded five rounds with 107 SMKs at touch and five jammed .010, both with 28 grains Varget. I normally run around 28.8. Both sets shot 4 shots nicely at under 1/4" at 100 yards but there was a pilot area on 1 of each set. Still under 3/4" when all was measured in. Shoulders moved out from 1.555 to 1.558 according to my comparator. I'm satisfied with the results. I may resize to just reset the necks and avoid touching the shoulder for one more round to be certain the shoulders are set.