BRA brass question

[Gilbert Garza]

I recently received my BRA reamer and cut the chamber as per directions with a BR-.004 go gauge. My question & problem is with new BR brass the bolt is firm to close. If I run through the full length sizer just enough to touch the shoulder on 2x fired brass it moves the shoulder neck junction just a tad. Is this recommended?

After the first fireforming the bolt is stiff to open. I’m using 29.5g Varget 105jlk & Hybrids.

 

[MDM]

That's what most are doing I think. When I did mine, I just headspaced as normal, Go +.002 so I wouldn't have to deal with the stiff bolt close and open in case I shot the FF loads in a match. Just yesterday I contoured and chambered a cheap 9 twist GM, 21" blank and set it up with a nut so I could put the headspace wherever I want for future fire forming.

 

[Alex Wheeler]

The -.004" is standard Ackley. I have run into cases when new brass actually fit perfectly. Most will need to bump .002". I want you to fit the brass to the chamber as perfectly as you can because the quality of the formed case will be better. If your new cases have an oal spread of .002" your formed case should still have an oal spread of .002". That tells you your doing a good job. If you have heavy bolt lift back off the charge. The brass is not grabbing the chamber to help reduce bolt thrust yet.

 

[Terry O]

new BR brass the bolt is firm to close

It depends on your definition of firm. Too firm could be opening yourself up to scoured bolt lugs. If new brass is too tight, run them through your FL die to achieve the desired snug fit. 29.5 gr of Varget should be okay but every barrel is different. Try backing down to 29.0 and see if there is a difference.

 

[Gilbert Garza]

It depends on your definition of firm. Too firm could be opening yourself up to scoured bolt lugs.

I guess i feel it like it’s upper end pressure but not a “click” from high pressure. Usually on my AI I can lift bolt with index and next three fingers rather easily. With this I have to use more the hand. I’ve looked at the lugs, AI have very hard lugs scouring hasn’t been an issue so far.

 

[Gilbert Garza]

The -.004" is standard Ackley. I have run into cases when new brass actually fit perfectly. Most will need to bump .002". I want you to fit the brass to the chamber as perfectly as you can because the quality of the formed case will be better. If your new cases have an oal spread of .002" your formed case should still have an oal spread of .002". That tells you your doing a good job. If you have heavy bolt lift back off the charge. The brass is not grabbing the chamber to help reduce bolt thrust yet.

I cut my die yesterday and was finally able to full length size all my brass and bump then shoulders .002”. It chambered real easy and extraction was smooth. For giggles I sized 2 pieces of virgin brass based on my full blown cases and you can see where the neck shoulder junction is moved ever so slightly. Those 2 pieces of brass chambered very easy, bolt almost just fell closed.

Should I do something to the chamber or just start fireforming all the rest of my brass. I’ve been working with only 10cases before I’m ready to settle on the chamber. Still have 390 pieces to fireform.

 

[Stan Taylor]

Well I will probably get some grievances here but if you have the BRA reamer I would have added a couple thousands to headspace then you probably wouldn't be running in to this problem on a wildcat cartridges you the individual maintain the headspace needed for good extraction with your dies that is why it's called an improved case no matter whether it's a bra or a dasheror whatever it is.

 

[Northridge]

Well I will probably get some grievances here but if you have the BRA reamer I would have added a couple thousands to headspace then you probably wouldn't be running in to this problem on a wildcat cartridges you the individual maintain the headspace needed for good extraction with your dies that is why it's called an improved case no matter whether it's a bra or a dasheror whatever it is.

I actually would agree here if you don't like something about a given headspace slightly adjust it to you feel etc. kind of a sliding scale with in reason.

 

[Stan Taylor]

I actually would agree here if you don't like something about a given headspace slightly adjust it to you feel etc. kind of a sliding scale with in reason.

A very good equation thanks for your response.

 

[Alex Wheeler]

Very true, its a"wildcat" do it anyhow you want.

 

[Gilbert Garza]

i get what y'all are saying, that makes sense, it i find it to firm on virgin brass open it slightly so virgin brass closes fine. Shoulder is still gonna form to the chamber, now with .002' longer headspace.

i think i read that correctly, sorry for the newbie questions, new to this and new to BRA.
Thank You

 

[BRGUY]

The only way to learn is to ask questions, so never feel bad about that!

 

[Stan Taylor]

Well there have been so many of this gentleman shooting various versions of 6br improved cartridges the BRA in question of yours I think the whole purpose was to be able to fireform cases without having to use false shoulder not having to jam bullets it's pretty obvious it has been very efficient for a lot of shooters has a new pending light gun group An score records in 1000yd benchrest.PS plus I think there's a couple aggregate records also from last year I think.

 

[mikeeg02]

i get what y'all are saying, that makes sense, it i find it to firm on virgin brass open it slightly so virgin brass closes fine. Shoulder is still gonna form to the chamber, now with .002' longer headspace.

i think i read that correctly, sorry for the newbie questions, new to this and new to BRA.
Thank You

Couple things about bumping back virgin brass, especially if you're jumping your bullets. Make sure you still have some pressure on bolt close, because if you're using harder cupped primers they may not go off. As nature boy and myself experienced. (And I'm sure others have) I didnt check every case, and I still had pressure closing the bolt, but out of 90 shells at the last match, 5 didnt go off. I assumed I didnt put powder in the cases, but when I pulled the bullets there was the powder. It's not as prevalent with softer cup primers like a 205, but my fire form load for the br-improved is 29.6 of my lot of h4895 and 450 primers. So if you're using harder cupped primers, make sure there's pressure. I remedied my situation by seating the bullets long in those 5 cases and firing again.

 

[Nature Boy]

because if you're using harder cupped primers they may not go off. As nature boy and myself experienced.

Quite right.

50% failure rate with #450 primers during fire forming. 100% success rate with them after fire forming.

 

[mikeeg02]

Quite right.

50% failure rate with #450 primers during fire forming. 100% success rate with them after fire forming.

I didnt have that bad of a failure rate, but when adjusting my die I did make sure I had some pressure still. Apparently 5 of the cases were difference enough that even with a second strike, they did not go off. And even with not being able to take my last two shots, that rifle/load took third at the last 800-1k steel match I went to. Second was one point higher then mine. They definitely shoot competitively while fire forming. Though with formed cases it prints better at 200 than it did forming. Consistently too!

 

[Sheldon N]

On my BRA the brass would have a firm close on about 80% of the cases, with a couple of them closing a bit too easily. I chose to jam bullets in addition to the natural chamber headspace. Got very consistent blow lengths.

Agree too on using softer primers like Fed 205's. Those have worked great for me while I've gotten failure to fire with 450's.

 

[Gilbert Garza]

So far in my 610 fireforming cases between 10 in BRA and the rest in Dasher I’ve yet to have a failure to fire. But in Dasher I was jammed .020” with out of box neck tension. For BRA its just the longer case that’s helping.

 

[Gilbert Garza]

The only way to learn is to ask questions, so never feel bad about that!

I guess it’s not a bad sorry but more of a thank you sorry, like when you burp after a great meal. I appreciate all the advice & guidance, wish some of y’all lived closer to buy you a drink or dinner

 

[BRGUY]

Understood...

Wish I did live closer, I'm hungry!