Trouble with the bra

[Matt_3479]

So I got a 6bra about 2-3 weeks ago and just firing forming the brass. I have never experienced so many light strikes/failure to fire. At first I thought maybe not deep enough primers. Pushed them in further and it got worse. I’m assuming cause I’m touching lands and not Jamming so it’s allowing the case to shift when firing pin is being struck? Is this what Most would assume?

on the good side, it’s bloody accurate when it does fire lol. 0 load development, new brass, 0 work

 

[varminthunter1]

Excessive headspace might me the culprit.
BRA should be .004" shorter than a br go gauge.

 

[varminthunter1]

Read this thread.
Lots of great info.

Alex's 6 BRA fire forming method

Could one use the crush fit method as used for the 6 BRA instead of the false shoulder method to fire form a 6 Competition Match? Alex mentioned in one of his posts the 6 BRA chamber closely fits original 6 BRA brass. Is this a critical factor for fire forming with the crush fit method? IDK...

forum.accurateshooter.com

 

[JFrank]

I had a slight crush fit when closing the bolt, jammed the bullet a tad over 29.5 gr. varget CCI 400 primers. The entire 100 fire formed without any issues.

 

[Sheldon N]

Using CCI 450 primers? Those have a harder cup and are prone to light strike on fire forming.

 

[Henryrifle]

@Matt_3479: This is probably way off base but I once paired a Bix'n Andy Competition trigger that had a reversible sear with a BAT VR action. 1 out of 10 rounds resulted in a failure to fire and the inconsistent primer strikes yielding poor groups and SDs.

The solution was to reverse the sear insert and all was good.

That doesn't sound like your problem as your accuracy looks good at this stage of fire forming and barrel break-in but I thought it worth mentioning.

Henryrifle

 

[DiffEQ]

...and my mind always in the gutter, I read your title and think of papas and beer.

 

[Matt_3479]

Using CCI 450 primers? Those have a harder cup and are prone to light strike on fire forming.

yes sir I am. I just read that else where.

 

[shoot4fun]

yes sir I am. I just read that else where.

With the correct .004 crush as already mentioned the CCI450 should not be causing you to have multiple misfires. We don't need to know who chambered the barrel but I really think a conference with them is in order. Hopefully the 'smith is close enough that you can take the rifle there for some measuring and investigating. I for one do not suspect primers are the issue.

 

[Matt_3479]

Well I may have finally figured it out. When seating back slowly I found that 1.1863” to be where bolt closed with ease the first time I did it (last week) tn I noticed that slight click when opening and started again tonight to double check my numbers. When moving in slowly I got to 1.870 and it was slight pressure on close and when I opened back up I dropped the bolt and it closed without any hesitation. I measured and it read 1.870” so I started questioning. I moved back to 1.890 and it closed with resistance but it pushed the bullet into 1.8885. I put the same one back in, and it pushed the bullet back to 1.885, then again to 1.882 and then I cycled 4-5 times and it stopped at 1.881. The is the absolutely slightest resistance for the first close then if cycled a second or third time it drops free. So I believe 1.881 is my actual touch point. There is still a click at the top but was told that is something to do with impacts and not too worry about it. If this is the case, I would of been .018 thou from touch which may be causing my light strikes

 

[pappaw]

Well I may have finally figured it out. When seating back slowly I found that 1.1863” to be where bolt closed with ease the first time I did it (last week) tn I noticed that slight click when opening and started again tonight to double check my numbers. When moving in slowly I got to 1.870 and it was slight pressure on close and when I opened back up I dropped the bolt and it closed without any hesitation. I measured and it read 1.870” so I started questioning. I moved back to 1.890 and it closed with resistance but it pushed the bullet into 1.8885. I put the same one back in, and it pushed the bullet back to 1.885, then again to 1.882 and then I cycled 4-5 times and it stopped at 1.881. The is the absolutely slightest resistance for the first close then if cycled a second or third time it drops free. So I believe 1.881 is my actual touch point. There is still a click at the top but was told that is something to do with impacts and not too worry about it. If this is the case, I would of been .018 thou from touch which may be causing my light strikes

Bullet seating on a bra chamber is not your problem, you are covering the problem up with the seating depth.. It should fire a primer with no powder or bullet if the head space is correct, period !!

 

[LCazador]

yes sir I am. I just read that else where.

Assuming your brass has been fireformed at least once then it might be an ignition issue. If you're fireforming seat your bullet well into the lands, use a moderate load, and heavy neck tension.

 

[Tokay444]

It sounds as though Matt’s chamber may be too long at the neck shoulder junction, if a BRA is supposed to be .004” shorter than a standard BR.

 

[DocDoc]

The Ackley version is supposed to be 0.004 shorter than the parent. There should be slight resistance on closing the bolt on unfired BR brass. You should not have to jam bullets to get the parent to fire and form correctly in an Ackley chamber.

 

[Matt_3479]

Bullet seating on a bra chamber is not your problem, you are covering the problem up with the seating depth.. It should fire a primer with no powder or bullet if the head space is correct, period !!

I’m somewhere between .007-.010 long on headspace. I was able to put 3 pieces of painters tap on the back of the case before resistance.

 

[ttfreestyle]

I’m somewhere between .007-.010 long on headspace. I was able to put 3 pieces of painters tap on the back of the case before resistance.

Was this a new unfired case?

 

[Matt_3479]

Was this a new unfired case?

Yes. So I measured each piece of tape and it came to .003, .0065, .010

 

[pappaw]

I’m somewhere between .007-.010 long on headspace. I was able to put 3 pieces of painters tap on the back of the case before resistance.

You found your problem, headspace

 

[JFrank]

You found your problem, headspace

Yep
Not seating, never was.. Maybe ran them through a ill set die prior to loading.

 

[wzee]

Yep
Not seating, never was.. Maybe ran them through a ill set die prior to loading.

What kind of action is it?? If its a panda let me know you might need a offset trigger hanger had the same problem. Working great now