Measuring primer seating depth

[6530]

I'm new to reloading and have recently started loading 300 WSM. My question relates to measuring the seating depth of the primer in the brass. I'm using Winchester brass and large rifle primers, and priming by hand using the RCBS tool.

Using the hand tool I can feel the primer actually seat in the pocket. The first few times I seated primers I didn't close the tool handle all the way (i.e. the primer seating rod was not at the limit of its travel) thinking that I didn't want to seat the primers too deep, but I discovered that even when I closed the tool handle all the way the primers weren't seated deep enough.

I tried to measure the seating depth using a known straightedge and a 0.005" feeler gauge, but it didn't seem that the primers were deep enough - even with the tool at its limit.

Here are my questions:
1. How can I seat the primers any deeper, or is the tool designed to automatically seat at the right depth?
2. How can I effectively measure seating depth? I realize that I'll probably get a feel at some point, but (a) being new I want to check myself, and (b) I don't want to develop the wrong feel.

Help!

Thanks.

 

[Mal H]

The RCBS tool is designed so that if you compress the handle to the stop, the primer should be seated deep enough.

The best way to measure actual seating depth is with the depth measuring end of a caliper. Set the end of the caliper over the head and extend the stick until it just touches the primer. Be sure the caliper body isn't raised off the head when the stick touches the primer.

If you don't have a caliper (you should), then use your straight edge and simply use your calibrated eyeball to see if there is some space between the primer and the straight edge. It's hard to actually measure how deep the primer is with that method, but if you see some space you know it is at least below the head surface.

A third method is to simply look at the primer. It should be obvious if it is below the surface of the head. I guess this is the method I use most often.

 

[P95Carry]

Mal H has said it ....... but, would add that, even if pockets are clean the last bit of travel needed to get primer seated is the hardest.

IMO .. the whole insertion process needs done quite briskly ... almost like ''having enough momentum'' ..... if ya see what I mean. Stop 95% short of full depth and that last bit is way difficult. Be bold and ''go for it'' ... a firm stroke to the limit every time. It only takes a high protrusion of even a thou' and it's awkward.

 

[Standing Wolf]

...and simply use your calibrated eyeball...

My index finger is calibrated a lot more tightly than my eyes. Whenever I'm in doubt about a primer, I compare it to the primer in a factory round. If they feel the same, I figure it's seated right.

I started fingering each finished round's base quite a few years ago after a few rounds in my second batch of hand-loaded ammunition failed to fire.

 

[Tim V]

? did you uniform the primer pocket if not try that to get them to the correct depth.
As for measuring the depth I use my RCBS case master with the drop indicator I think this gives a more acurate reading :banghead:
Tim

 

[cheygriz]

The primer should be seated to the bottom of the primer pocket! Period!! If your press has a primer seater stop mechanism, take it off and throw it away.

Seat your primers by feel. Bench rest shooters have always used this method, and you know how anal they are about consistency.

For years, I used the RCBS bench mounted primer tool with complete satisfaction. It allowed me to "feel" the primer bottoming out in the pocket.

With increasing experience, you will feel this on virtually any reloading machine. I still use the seat by feel method even with the Dillon XL 650.

 

[P95Carry]

I've just remember one other aspect of priming too ........

When the primer cup is fully seated in the pocket .. the anvil (boxer primers, of course, though even a Berdan should be seated onto the case anvil)) ...... is put under slight tension and thus is ''seated'' into the priming compound. This is reputed to slightly ''sensitize'' the compound as a result, and thus ensure that the pin strike is fully effective.

If you look at a primer it is usually possible to see the slight protrusion of the anvil ''legs'' ... representing the amount of travel that will occur on full seating.

 

[Thirties]

"If you look at a primer it is usually possible to see the slight protrusion of the anvil ''legs'' ... representing the amount of travel that will occur on full seating."

OK, how about posting a photo for some of us lees experienced folks here.

 

[P95Carry]

OK, how about posting a photo for some of us less experienced folks here.

Here ya go .... now these are large rifle primers ... pretty damn small to get decent pics but .... look close and you should see that the ''legs'' of the primers are slightly proud. Pick up any boxer primer and it should be pretty obvious.

 

[Thirties]

Thanks!

 

[6530]

OK, I'll give it a firmer try next time...and hopefully all will be well.

Thanks for all the replies & advice.