Fired brass not chambering. Need help.

[Truck Fireman]

Got a 6bra. After fireforming and then shooting in the gun with a fireformed round the fired case will not chamber without a hard bolt close. I full length resize and bump the shoulder back 2 thou. Still won’t chamber without hard bolt close. Eventually I had to bump the shoulder back 5 thousands to get the brass to chamber with a normal bolt close. Anyone have any idea what’s going on???

 

[NineHotel]

will the brass rechamber just fine before you run them into the sizer? What are you using the measure how far back you are setting the shoulder?

Full length sizing (I'm a fan of it) moves quite a bit of brass around, from the base to the tip of the neck. Depending on how you are measuring, you may not be getting an accurate measurement when you say you bumped .002".

Do you have a case gauge for this chambering?

 

[mdmp5]

Sounds like it’s not the shoulder setback, but the bottom part of the body that is sticking. That extra 3 thou of shoulder bump is sizing a little more of the body which makes the brass fit in the chamber. Just my theory

 

[supercorndogs]

One of those two things.

 

[Truck Fireman]

Using a SAC comparator for 6bra. Brass won’t fit after firing or after full length sizing until i bump the shoulders back 5 thou or more.

 

[sirhrmechanic]

Above are where to start.

Some more food for thought...

Try coloring your brass with a sharpie and seeing where it is sticking. Or spray with machinists blue/Dykem.

You might also be creating a ring that bulges out just below the shoulder if you are pushing the shoulder back aggressively.

Is your chamber clean?

Cheers, Sirhr

 

[mdmp5]

Take some spot measurements of the brass prior to fireforming and compare to after, and then sized. Especially take note of that area on the lower body

 

[memilanuk]

I think @sirhrmechanic is on the right track. You can measure this, that and everything else til you lose your mind... or you can coat the cases with a Sharpie, and let the gun show you where the problem is. Then start measuring.

I've had some issues in the past with using brass from one barrel in the next... had to use a small base die or a ring die to 'fix' things. I've also had issues where some rims were all fubar'd (AR15/5.56). Less common (for me) but still had it happen at least once, was where there was a mismatch between the dies and the chamber, and ended up having to get custom dies made from my fired brass.

Good luck.

 

[opus56]

I've seen this happen if the chamber has any sizing lube residue left in it from sizing a piece of brass, lazily wiping it off and chambering it to see if it works. Between what's in the chamber and on the brass, the bolt will be stiff if it even closes at all.

 

[LawnMM]

Neck too long?

 

[Nimothy]

What dies are you using? I had to shave my whidden dies at the bottom for them to work.

 

[midwestoffroad]

You did trim them didn't you?

 

[Nimothy]

You did trim them didn't you?

I do t see that being the issue. Maybe but in my experience not likely. I’m assuming he is using lapua cases and I know it’s formed brass, but I own lapua cases for every chambering I load for including bra and have never measured a new lapua case over min length out of the box. I think we are missing some key info here, like what his fireform load was and what kind of dies he is using and who chambered the barrel and does he have a reamer print.

 

[Truck Fireman]

I’m not sure how the die has anything to do with it. The brass shot through the rifle once already. Before sizing anything the fired brass goes in the chamber with an extremely hard bolt close. I then have to bump back 6 thou to get it to chamber smoothly.

 

[AIAW]

.006” bump is a lot... Like some have said, Sharpie a case up, chamber it over and over about 5 times and take a picture/post it for us.

That will pretty much concrete where the issue truly is.

 

[spife7980]

Coat it in sharpie to visually see the interference.

Take some actual measurements and compare to your reamer print if you can.

 

[MarinePMI]

When you have a die that isn't sizing the web enough you usually feel the effects extracting not chambering. If bumping your shoulders fixes your problems then it's not an expanded web problem

Respectfully, that is not always the case. Way back when, when the 6.5 CM was the newest thing on the block and brass was made from unobtainium, I had to form it from .308. Long story short, the brass would not chamber because in the forming process, the web was too large, and the die was not sizing it all the way down the case. Marking a case, showed where it was rubbing, about .3" up the case wall. A SB/Body die solved that.

This may be a similar case, where bumping the shoulder back more, is actually just sizing the case lower down near the case head.

 

[memilanuk]

This may be a similar case, where bumping the shoulder back more, is actually just sizing the case lower down near the case head.

I agree... though it does seem odd that brass fired in the same gun is chambering hard, immediately after extraction/ejection, if I'm reading correctly what the OP is saying.

 

[Truck Fireman]

That is correct. I can take it straight from ejection and try to reinsert and hard bolt close.

 

[Nimothy]

That is correct. I can take it straight from ejection and try to reinsert and hard bolt close.

Do you have a reamer print? Can I ask your load data and can we see a fired case?

 

[Nimothy]

These are fireform loads right. Like first firing. You are still forming brass right?

 

[Nimothy]

Frankly with these

Frankly with these internet puzzles anything is possible. The problem statement is delivered by someone who doesn't understand what's going on so the information you are getting is already obfuscated.

In my experience with 3 chambers/ die combos expanded webs that resulted in hard extraction did not result in hard chambering. The OP still hasn't answered the question I asked twice about measuring headspace with fired primers in the cases

I’m not sure he is answering any questions. He kinda just argues. Which is ok but I shoot a bra that had chambering issues as well. Can’t help those who don’t want it.

 

[Truck Fireman]

Not arguing. And no sir I’m not measuring headspace with the primer still in the case. Just don’t get back to the site much during the day. Once I get home tomorrow I’ll try the sharpie test and see what I get.

 

[Truck Fireman]

Hand held Frankfort decapper

 

[midwestoffroad]

I do t see that being the issue. Maybe but in my experience not likely. I’m assuming he is using lapua cases and I know it’s formed brass, but I own lapua cases for every chambering I load for including bra and have never measured a new lapua case over min length out of the box. I think we are missing some key info here, like what his fireform load was and what kind of dies he is using and who chambered the barrel and does he have a reamer print.

My Dasher brass was .020 to long after fire forming . It's quick check

 

[Nimothy]

My Dasher brass was .020 to long after fire forming . It's quick check

Very true.

 

[Sheldon N]

I've heard of other issues similar to this with the 6BRA, specifically having to bump the shoulder a few extra thou in order to get smooth chambering. Spent a fair bit of time discussing with my gunsmith too.

Suspected cause is the neck/shoulder juction radius and or stacked tolerances with the shoulder angle of the chamber vs the shoulder angle of the dies not matching exactly.

Not ever run into this myself, but is something I've heard of before with 6BRA. My suggestion would be sharpie to see where the interference point is.

 

[blaserman33]

On Accurate Shooter I have heard of a couple guys having to shorten their dies slightly, but I think those were Harrel’s Dasher Dies that has been shortened to BRA length and I don’t recall if it was because it wasn’t sizing the base enough or if it wouldn’t allow them to bump the shoulder enough, so could be completely different deal there.

I agree that he either needs to get the reamer dimensions, or color a case and see where the interference is taking place, but it’s extremely strange that it won’t chamber immediately after ejection. That doesn’t make sense to me unless the cases were super hot as the ejected and continued to expand after ejection.

What kind of action is it? Action shouldn’t play in to it, but could there be some kind of varying headspace if using a floating bolt head style action that is defective or out of spec? I doubt it, but I am just thinking out loud here. But not being able to re-chamber a recently ejected round is really strange.

 

[Deleted member 10043]

Coat it in sharpie to visually see the interference.

Take some actual measurements and compare to your reamer print if you can.
View attachment 7219301

YES, THE WEB AREA!!!

 

[sirhrmechanic]

@Truck Fireman ...

Ever figure this out?

Cheers, Sirhr

 

[Truck Fireman]

I was getting different length of brass depending on load I used to test. So I took 10 rounds and fired all at the same charge weight and took the average measurement of those and used that measurement to bump my shoulder back 2 thou. It seems to have worked itself out. Not exactly sure of the answer.