what is the right depth for a small primer on a 6 mm br

[shaunharkin]

hi there guys looking for some help again what is the right primer depth on a
6 mm br lapua brass thank you

 

[zullo74]

Is this a trick question?

Primers need to be seated until they bottom out in the pocket of course! What did I win?

 

[dantiff2]

On Lapua brass, I have .009 thou below flush on all primed brass...

 

[mikecr]

I seat with .002 crush on eah primer, except with BR4s(these need .005 crush).
I do this with the K&M primer seater, and don't know of any other way to do it.

 

[Preacher]

They only go in so far unless you cut the pockets deeper..
Crush one to much and it will crack the compound and ignition will
get weird...

 

[Link]

I seat my primers flush with the brass.

Is this wrong?

thanks

 

[maxpower]

This whole primer crush thing interests me as well. I have found I have been crushing mine .006", while another shooter who is getting great scores has measured his crush at .002". We were both using Wolf primers. As we used different primer cup clean up tools, our depth measurements varied. I think the amount of crush is more important than the actual depth. I am hoping someone else here has done some experimenting with primer crush.

 

[tripcrow]

CCI wants their primers seated .003”-.005” below the case head.

But the rub is that one of my primer pocket uniforming tool says that SR, SP, & LP primer pockets are to be .118”-.122” deep. LRs are suppose to be .128”-.132”.

So I’d guess the best numbers would be a primer .004” below flush on a .120” deep SR primer pocket. But my Lapua pockets are max deep to start with. So I seat CCIs .005"-.006" below. I gave up trying to seat them by feel decades ago.

 

[BoydAllen]

Link,
Yes

 

[mikecr]

For one, .002" crush does not mean .002" below flush.
Flush/below flush means nothing w/regard to crush.
And two, CCI has no idea what their primers should be seated at -in YOUR brass, because they haven't a clue about YOUR pocket depths.

CRUSH means seated to touching bottom of pocket + desired additional. This means measuring every single primer, and every single pocket each is to be seated in, and then measuring the actual seating.
K&M is the only seater I know of that provides this.

The 'proper' crush is beyond me as I haven't done alot of testing there.
But I do know that primers misfire without some amount of crush.
And I know it can depend on the strike the bolt provides, and the case headspacing needed. It's not about power, but speed(sharpness) of strike. Heavy pins, high viscosity spring lube(cold), pin travel causing the bolt handle to move(misaligned bolt turn), or anything moving forward with the strike(primer or case), can affect primer performance.

So with conditions unknown, I start at .002" crush, and bring the seater to the range. If I get misfires, I seat the next 10 .001" deeper, until all are firing well. That's it, I just seat till they are reliable & log it.
Maybe some day I should do some testing..

I've never used anything but the K&M. It's a nice seater, but I notice it would be impossible to seat with it, to a set crush, -by feel. No Way.
It would be interesting to do some testing with the Sinclair wonder seater that looks so nice. I could measure things out with the K&M, seat by feel with Sinclair, and remeasure to see how I did with the K&M.
But I can't see spending so much on a seater that I highly doubt can seat with K&M's precision.

Anyway, as far as consistant seating w/resp to 'flush', this of coarse could be achieved with pockets milled to a standard depth. So if not acounting for primer thickness variance, I would at minimum uniform the pockets ..

 

[BoydAllen]

Virtually all of the short range Benchrest shooters that I have seen load, between matches at the range, seat primers by feel. It is easy. Lets not make buttering bread into an engineering problem. Seat the primer till you feel it bottom and then compress it a little more. A hand tool makes this easy.

 

[Mikem]

I'm going along with BoydAllen on this one. Make sure your pockets are clean, so the primer bottoms out on brass, and the primer is below the case head.
I don't think any fancy tools are required to determine primer depth, and I doubt the depth variation will show up on the paper.
I seat all primers by feel with a hand seater, and have never had a F.T.F. And both of my BRs shoot just fine.
This part is not rocket science, in my opinion.
Mike.

 

[expiper]

over the yrs I have seen several tools and methods used to seat the primers ....to me it seems like how to open a bottol-0-pop,,,just pull on it till it fizzzess....hahah....there are tools that uniform the poket depth ...and tools that seat to a millionth of an inch below flush etc...but every tool and every method relies on the rim to do the pushin....and the rims vary in thicness!! hmmmmm....I use a Lee primer tool (12 $$) and just seat em till there is a lil crush .....so far so good... spend your money on a good powder measure (not on labratory scales or 200$$ primer tools...) I try to use tools and methods that can work on the tailgate of my truck in a hailstorm out on the range...Roger

 

[fdshuster]

Been loading match quality ammunition since 1960, and never realized seating primers was such a scientific and complex issue. Always have seated them 'til I feel them bottom out, which ends up being slightly below flush. Is it .002", .004" or ? Don't know and don't care. Cannot remember the last primer mis-fire I've had, and I average 3K to 4K per year.