Expand neck and partial size or just shoot?

[pdhntr]

Just finishing the stock on my new 6BR and hoping to shoot it this weekend. This is my first 6BR and I have a question.

Do you guys neck up the new brass and form a false shoulder to fire form the case the first time?

Or can I just load up some bullets and do a break-in on the barrel? Don't know if it matters or not but the headspace is at .001

Thanks.

Jim

 

[fdshuster]

Jim: I'm confused. If you're using Lapua or Norma 6BR brass there is no required "fire-forming". Just load 'em up as you would any other cartridge & go shooting.

That is, of course, with not having a tight neck chamber that requires outside neck turning, having the sizing die adjusted for proper headspace control, etc.

 

[pdhntr]

Jim: I'm confused. If you're using Lapua or Norma 6BR brass there is no required "fire-forming". Just load 'em up as you would any other cartridge & go shooting.

That is, of course, with not having a tight neck chamber that requires outside neck turning, having the sizing die adjusted for proper headspace control, etc.

And your confusion is warranted as I haven't done this before, and concerned about something that may not be significant.

I am using Lapua brass, and the reamer is a .270 neck cut with a reamer PTG marked for Lapua brass. The first test round after chambering expanded just enough to let a bullet slip into the neck with no play.

I have been reading as much as I can regarding this, and I may have mistook a post about fire-forming 6BR.

I feel I am an accomplished reloader with several wildcats that I have built, and my thoughts are just load up some and fire them as I have done with others.

But I am in new territory here with the Lapua brass, and didn't want to make a mistake that will have a negative effect on it.

Thanks so much for the response.

Jim

 

[fm1947]

Agree load them up and shoot , lapua is great brass.

 

[fdshuster]

jim: Just to verify your chamber neck diameter, take a fired case & measure the diameter with a micrometer. I bet it will be .269", and if you're using the "new" blue box Lapua with the slightly thinner necks, your loaded round neck diameter(s) will be .2665"/ .267", a perfect no-turn combination.

Try to determine your chamber over-all-length ( from the reamer print drawing?), or by using one of the Sinclair case length gauges. Then keep your trim to length measurements within approx. (whatever you're comfortable with) .010" of that length. That will stop the ring of carbon that will sometimes form at the case mouth section of the chamber.

Actually if you're not oversizing the brass/ pushing the shoulders back excessively, there will seldom be any case length trimming required. When closing the bolt on a loaded round, I like to feel a little resistance, telling me the cartridge is locked up tight, front to rear, in the chamber.

Have fun with this great round, easily my favorite.

ps: Forget to mention. Every once in a while, before sizing, try to slip a bullet into the case. If it falls all the way into the case, no donut. If it stops with the base at the neck/shoulder junction, a donut is forming. You must either remove it or make sure the bullet is seated forward of the donut. They are real, they do form. I never believed it would happen to me, but I've since learned another lesson.

 

[rain164845]

Is this a dasher or a BRX, or a 6mmBR like your post says?

 

[pdhntr]

Is this a dasher or a BRX, or a 6mmBR like your post says?

6BR

Jim

 

[pdhntr]

jim: Just to verify your chamber neck diameter, take a fired case & measure the diameter with a micrometer. I bet it will be .269", and if you're using the "new" blue box Lapua with the slightly thinner necks, your loaded round neck diameter(s) will be .2665"/ .267", a perfect no-turn combination.

Try to determine your chamber over-all-length ( from the reamer print drawing?), or by using one of the Sinclair case length gauges. Then keep your trim to length measurements within approx. (whatever you're comfortable with) .010" of that length. That will stop the ring of carbon that will sometimes form at the case mouth section of the chamber.

Actually if you're not oversizing the brass/ pushing the shoulders back excessively, there will seldom be any case length trimming required. When closing the bolt on a loaded round, I like to feel a little resistance, telling me the cartridge is locked up tight, front to rear, in the chamber.

Have fun with this great round, easily my favorite.

ps: Forget to mention. Every once in a while, before sizing, try to slip a bullet into the case. If it falls all the way into the case, no donut. If it stops with the base at the neck/shoulder junction, a donut is forming. You must either remove it or make sure the bullet is seated forward of the donut. They are real, they do form. I never believed it would happen to me, but I've since learned another lesson.

It just so happens that I measured the one fired case and you are correct. I am using the blue box and agree with you, this should be an excellent combination.

I can get the chamber overall length from the reamer print. (just as soon as PTG sends it to me)

I am no stranger to donuts and will be watching for them.

Thanks again for all the good information.

Jim