Barrel break and fire forming with non benchrest bullets

[6mmbra Dan]

I've been shooting 6BRA and Dasher since early 90s. Several things that I do to fireform brass are: seat the bullet well into the lands so the case is held against the face of the bolt for a good fireform. Because you are seated into the lands use a moderate load. You want a good fireform but not a load that's going to stretch the brass excessively. So the load that works well for fireforming is pretty much worthless for any actual precision shooting. Thirdly I'd like to add one of my primary goals while fireforming is to keep the barrel cool so I don't get alot of fire cracking going early. Doing this is not going to contribute to any great groups because it could be 5 minutes before you shoot your next shot. Use the junk stuff to fireform and don't do more than 20 at a time. Fireforming just 20 rounds can make for a long day at the range!

I've done a lot of research before landing on rebarrelling and rechambering my old 22-250 AI to 6bra. I purchased a ptg 6bra go gauge which is supposed to be .004 shorter than the parent case. I assumed that this would ensure enough jam to keep the case from moving forward during fire forming without jamming the bullets into the lands. I plan to use soft cup 205m's during my fire form process then progress to cci 450's for my final load development. Moderate load as you state somewhat escapes me, I know jamming bullets raises pressure and to what extent how do i determine I have excessively stretched my brass? Mic the case for expansion, hard extractions. On my old ackley i had my smith make me a headspace gauge using my chamber reamer from a left over barrel cut off i attached to my Vernier caliper to check variations on my virgin brass and to check when my shoulders needed pushed back.

 

[LCazador]

I've done a lot of research before landing on rebarrelling and rechambering my old 22-250 AI to 6bra. I purchased a ptg 6bra go gauge which is supposed to be .004 shorter than the parent case. I assumed that this would ensure enough jam to keep the case from moving forward during fire forming without jamming the bullets into the lands. I plan to use soft cup 205m's during my fire form process then progress to cci 450's for my final load development. Moderate load as you state somewhat escapes me, I know jamming bullets raises pressure and to what extent how do i determine I have excessively stretched my brass? Mic the case for expansion, hard extractions. On my old ackley i had my smith make me a headspace gauge using my chamber reamer from a left over barrel cut off i attached to my Vernier caliper to check variations on my virgin brass and to check when my shoulders needed pushed back.

You know you've over stretched your brass when the head diameter exceeds .001" of your reamer dimension at this same place. Over 50 years I've done Ackley Improved chambers on most every cartridge I've owned. These recommendations are from Ackley himself and have worked for me perfectly over the years in fireforming brass.

 

[JMayo]

Do what you do. Have fun with your big boy toys !
My bra didn't come in until 800 rounds. I'll shoot this one all year prolly 2500+.
....
I'll take the $$ I win and buy another...
WHAT ..no money ... Still I'll just buy another anyway.

 

[INTJ]

Fireforming works great for the 6 BRA using 20 grains of Bullseye and 1/8 piece of toilet paper. Need a softer primer. Borescoping after fireforming 200 rounds showed only a light gray haze that quickly cleaned up.

 

[johara1]

Just fire forming and breaking in two barrels at the same time. I fire and clean 1 shot at a time till it quits making copper after I go over the throat Iooso. then I start to fire form cases 5 at a time with a chamber and rounds cleaned off with non chlorinated brake cleaner. after about 50 rounds of shooting them in the dirt, I start shooting them over Lab radar, with rounds that are weighed charges and then I watch the es. to see it go into single digits and repeat then I start load development.
One barrel was broke in around 60 rounds and the other has 120 and is still not totally broken in..... I guess you just can't put a number on it..... jim

 

[BCBRAD]

Where I can I use a Hornaday BTHP bullet .
Load them 10 thou into the lands.
Model the load on QL, shoot 5, adjust Ba to chronograph velocities, manipulate powder charge to an OBT. Load 5 more for proof.
Working on a fast twist 243Win right now, it is holding right around 0.750 moa (5 shots) with un prepped brass with an ES of 22 ft/s or less depending on the string.
This is valuable practice time and as a bonus get extended brass life.

 

[INTJ]

Here is the best way to break in a barrel: