6 BRA headspace issue

[LCazador]

Hi all, having an issue with my 6 BRA, I've got some used 6 BRA brass from two other rifles and it's ~0.012" shorter at the shoulder than cases fired in my barrel.

Background is that I bought the barrel for my Tikka secondhand, I know it's a no turn and I assumed it was otherwise the standard Wheeler #1. It came with 100 pieces fired brass and I checked the headspace against them after I installed the barrel, bolt was tight but would close on a fired case. It wouldn't close on a fired case with a single layer of Scotch tape, and the shoulder measured the same on cases fireformed on my action as the fired cases I was sent, so I'm sure it's not a barrel installation issue.

I got 20 6 BRA cases from one guy and they were 0.007" short at the shoulder (using a SAC comparator), I didn't use them but figured hey maybe that guy had a short chamber or sized them way too far. It's only 20 cases and they were free, I wasn't worried about it. But recently I just bought 250 pieces of brass from a different guy and they measure 0.012" shorter than my fired cases. So now I think it's most likely that my chamber is longer than standard. I now have 300 pieces fireformed to my chamber and 260 fireformed in other chambers that seem very nice but have way too much headspace, so I'm trying to figure out my next move.

As I see it I have four options:
1. Make a false shoulder and fireform (expand the 'short' brass to 6.5, then size down to my chamber's shoulder)
2. Load bullets long and jam to fireform
3. Sell the 'short' (really standard 6 BRA) brass
4. Shave back my barrel to standard spec and bump all my long brass back down to standard?
Any suggestions among these or other ideas?

I'm leaning toward #1 but don't want to work the brass (and myself) that much if it's not needed. I do have an annealer so I'm not worried about that part. Yes I probably should have just fireformed everything and not run into this problem but I'm cheap and used brass is cheaper than new. Thanks in advance.

Doesn't sound like a problem. Fireform the shorter brass with a moderate load and the bullet seated well into the lands. The tighter longer ones bump .003"-.004" and see if bolt loosens up. If they don't bump some more till they fit loose then fireform. No doubt your chamber is different but no so much you can't fix with a properly set sizing die and fireform to your chamber. I might add that forming a Dasher moves the shoulder up almost .150" so you moving up .012" shouldn't be a problem.

 

[Tokay444]

Maybe I missed it, but has the chamber been checked with go/no-go head space gauges?

 

[EricF]

Maybe I missed it, but has the chamber been checked with go/no-go head space gauges?

No, I have both a 6 BR Manson go gauge and 6 BRA PTG go gauge on order. Should have the former shortly. Yes, I should have done that to begin with.

 

[dnellans]

Hope this helps some:

 

[EricF]

Hope this helps some:

View attachment 1235503

Thanks. That matches well with shoot4fun, and it seems like my chamber is 0.003" deeper than both of yours. Maybe is was chambered flush with a 6 BR go gauge rather than 0.003-0.004" crush? Assuming the 6 BR go gauge confirms that then at least my barrel ought to be okay for continuing to fireform with (right?)

Many people think jamming with the short brass should be fine but a couple advise strongly against it. I really appreciate all the advice and measurements people have made.

 

[shoot4fun]

Thanks. That matches well with shoot4fun, and it seems like my chamber is 0.003" deeper than both of yours. Maybe is was chambered flush with a 6 BR go gauge rather than 0.003-0.004" crush? Assuming the 6 BR go gauge confirms that then at least my barrel ought to be okay for continuing to fireform with (right?)

Many people think jamming with the short brass should be fine but a couple advise strongly against it. I really appreciate all the advice and measurements people have made.

I may be wrong but I don't think it will be dangerous or disastrous to fie even the shortest of your brass in that barrel. I would anneal it, load it with a moderate 6BR charge and shoot it. Try and few first to see how it goes. After all, fire forming 6BR to BRA does require a bit of reshaping and moving of brass any way.

 

[dnellans]

Hard jam fireforming works, until it doesn't. Triggertech was more than forthcoming that they think that is the number one reason they get blown triggers returned to them.

 

[shoot4fun]

Hard jam fireforming works, until it doesn't. Triggertech was more than forthcoming that they think that is the number one reason they get blown triggers returned to them.

Pierced primers are a well known cause of trigger failure for some brands but never heard of this.
We must be talking about totally different hard jams for fire forming. Over the years I fire formed a lot of Dasher brass that way and never had any issue.

 

[EricF]

Hope this helps some:

View attachment 1235503

Got my 6 BR go gauge in. It measures 1.159 using the Hornady 350 comparator, and my bolt closes on it. With a packing tape shim it measures 1.162 and bolt doesn't close.

 

[Sheldon N]

Got my 6 BR go gauge in. It measures 1.159 using the Hornady 350 comparator, and my bolt closes on it. With a packing tape shim it measures 1.162 and bolt doesn't close.

So your chamber is about 0.003 too long, and whoever sized your new lot of brass oversized it by about 0.005 beyond what they should have done for a proper chamber.

If you have easy access to a smith to face 0.003 off the shoulder of your barrel that wouldn't be a bad thing. Would be easy to size your current brass a bit more to fit. If you wanted to use the short brass you could try fire forming it with jammed bullets and a light load.

 

[LCazador]

Hard jam fireforming works, until it doesn't. Triggertech was more than forthcoming that they think that is the number one reason they get blown triggers returned to them.

That is more likely due to folks shooting small primer brass with a large primer bolt. It blanks the primer with even a moderate load. Trigger Tech knows that or should know that?

 

[JMayo]

I'd fire form and shoot.
Making a problem where there is none. Imo

 

[Alex Wheeler]

Every 6BRA barrel I have chambered since the very first one ever stamped 6BRA has been .004" short on a 6br go gauge. Its an Ackley, .004" is standard. On some of my other improved chambers, I dont have to hold the chamber short at all to get a crush on a virgin case, on others I have to hold .010" short to get crush on a virgin case. Its the job of the smith to figure this stuff out and do it properly. You dont want sloppy virgin brass in the chamber if your trying to form consistent cases. Jamming bullets is not enough, you need some type of a shoulder.

 

[Webster]

Hi all, having an issue with my 6 BRA, I've got some used 6 BRA brass from two other rifles and it's ~0.012" shorter at the shoulder than cases fired in my barrel.

Background is that I bought the barrel for my Tikka secondhand, I know it's a no turn and I assumed it was otherwise the standard Wheeler #1. It came with 100 pieces fired brass and I checked the headspace against them after I installed the barrel, bolt was tight but would close on a fired case. It wouldn't close on a fired case with a single layer of Scotch tape, and the shoulder measured the same on cases fireformed on my action as the fired cases I was sent, so I'm sure it's not a barrel installation issue.

I got 20 6 BRA cases from one guy and they were 0.007" short at the shoulder (using a SAC comparator), I didn't use them but figured hey maybe that guy had a short chamber or sized them way too far. It's only 20 cases and they were free, I wasn't worried about it. But recently I just bought 250 pieces of brass from a different guy and they measure 0.012" shorter than my fired cases. So now I think it's most likely that my chamber is longer than standard. I now have 300 pieces fireformed to my chamber and 260 fireformed in other chambers that seem very nice but have way too much headspace, so I'm trying to figure out my next move.

As I see it I have four options:
1. Make a false shoulder and fireform (expand the 'short' brass to 6.5, then size down to my chamber's shoulder)
2. Load bullets long and jam to fireform
3. Sell the 'short' (really standard 6 BRA) brass
4. Shave back my barrel to standard spec and bump all my long brass back down to standard?
Any suggestions among these or other ideas?

I'm leaning toward #1 but don't want to work the brass (and myself) that much if it's not needed. I do have an annealer so I'm not worried about that part. Yes I probably should have just fireformed everything and not run into this problem but I'm cheap and used brass is cheaper than new. Thanks in advance.

I would just jam and fire. Since your shooting basically a factory rifle I assume you are not shooting serious competition. I get small groups FF my 6BRX. I shoot bench for fun and GH hunting. Nothing complicated here.

 

[Stephen Joubert]

Easy… bump back the long ones so they will chamber….. and shoot the short ones to match your chamber… after your brass is uniform bump your shoulders back about 2k and your good to go….

 

[6BRA]

Since standard 6BRA chambers should crush very slightly on brand new 6BR brass for fireforming, I'd have the barrel reworked to fix it.

If the headspace is off by 1/64" of an inch, then it begs the question of what else was done well.

I believe it's possible to use standard 6BR chamber gages - not sure why this barrel would be so far off.

If the bolt falls on a 6br go guage. It's cut long.

 

[urbanrifleman]

I'll take that brass. Let me know what you want to trade for it.

 

[bobbydubrx13]

I would be curious if anyone has had any experience with this since the OP. I have a 22bra and have found that the alpha 6bra brass is not a traditional br parent case -.004. it's actually about .010 shorter then what it should and is just the way they design it.

 

[6BRA]

I would be curious if anyone has had any experience with this since the OP. I have a 22bra and have found that the alpha 6bra brass is not a traditional br parent case -.004. it's actually about .010 shorter then what it should and is just the way they design it.

That's why I sold mine..lol. I showed them about .009 short. Plus designed for their Alpha reamer!

 

[bobbydubrx13]

That's why I sold mine..lol. I showed them about .009 short. Plus designed for their Alpha reamer!

Sold what the gun or the brass? It seems that we could just get the alpha 6br brass and it will be no issue, just like Lapua it will close with a crush for and be .004 shorter after firing. The part that confuses me the most is that like my Manson reamer doesn't use a 40 shoulder it is still a br gauge just .004 shorter then a normal br.. I just wish I could find a way to form the bra brass without stretching the the web but their brass is so hard that it doesn't grip the chamber walls very well when trying to move it ..010