Proper Primer Seating

lesterg3 · Posted: Sun Nov 30, 2008 12:14 pm Post subject: Proper Primer Seating

It seems to me that there is a lot of talk about seating primers properly, but no actual subjective measurements.

The best description I have found on the net is that the primer base should be .005 below the cartridge base.

The only way to do this properly would be to use a depth gage to determine the depth of the cartridges primer hole and the a caliper to measure the height of the primer. The result would be the most accurate space for the primer to be below the cartridge base.

Is this really that important or am I being anal?

wncchester · Member Joined: Apr 08, 2006 Posts: 160

"t seems to me that there is a lot of talk about seating primers properly, but no actual subjective measurements. The best description I have found on the net is that the primer base should be .005 below the cartridge base. ---- The only way to do this properly would be to use a depth gage to determine the depth of the cartridges primer hole and the a caliper to measure the height of the primer.

One, the best seems to be about 2-3 thou below the head of the case. That should put the anvil on the bottom of the pocket. Deeper would perhaps crush the primer compound at least sometimes, leading to misfires.

Two, use the center part of your dial/digital caliper as a "depth gage" for both the primer pockets and primer depth below the head.

1895ss · Posted: Sun Nov 30, 2008 12:57 pm Post subject: Re: Proper Primer Seating

I seat primers till I feel them bottom out in the pocket period. Never have had a problem. I don't care if they are .003 or .005 below the cartridge base, when they are bottomed they are seated as far as possible and work just fine. Why try to make it more difficult than it needs to be? Smile

denis · Posted: Sun Nov 30, 2008 3:41 pm Post subject: Re: Proper Primer Seating

lesterg3 wrote:

It seems to me that there is a lot of talk about seating primers properly, but no actual subjective measurements.

The best description I have found on the net is that the primer base should be .005 below the cartridge base.

The only way to do this properly would be to use a depth gage to determine the depth of the cartridges primer hole and the a caliper to measure the height of the primer. The result would be the most accurate space for the primer to be below the cartridge base.

Is this really that important or am I being anal?

Well, there are two things I do and the first is to feel the case head following the seating of the primer, especially if something doesn't quite feel right with the hand priming tool. The fingertips have more nerve endings than just about any other part of the body, and a high primer should be obvious.

The second is I have a piece of tempered glass that serves as a nearly perfectly flat surface and this will cause brass with a high primer to wobble when you move it from side to side.

By-the-way -- do this before you add powder and seat the bullet.

The rare times when I end up with a problem can almost always be fixed with another pass through the priming tool. If not, then you need to either reject the brass or deprime it and try again after cleaning the primer pocket (which is probably the reason it went high on you). I AM NOT MAKING A PARTICULAR RECOMMENDATION HERE, and there have been message threads where some respected reloaders on this forum have ended up on either side of the deprime/don't deprime issue.

Pumpkinslinger · Posted: Sun Nov 30, 2008 3:42 pm Post subject: Re: Proper Primer Seating

I'm with 1895ss. I just make sure that they are seated until they stop and that they are below the cartridge base. The only problems I've ever had with primers was when I failed to completely seat them, due to an equipment problem or my own mistake.

gelandangan · Posted: Sun Nov 30, 2008 4:02 pm Post subject: Re: Proper Primer Seating

+1 here..
I also seat them till they stop.

twofifty · Posted: Sun Nov 30, 2008 4:35 pm Post subject: Re: Proper Primer Seating

How I was taught a couple years ago and what works for me is to
first make sure the primer pocket is cleaned of combustion residue solids. There are inexpensive tools out there to do this, called primer pocket cleaners.

Then seat the new new primer until you feel a bit of extra resistance - this tells you the primer is seated. Because you cleaned the pocket in advance, you know that the resistance you feel is not due to pocket grit - this is safer and leads to more consistent results.

Finally, as you place the newly primed case in the loading block, feel with your fingertip to make sure the primer does not stick out beyond the cartridge base. Placing the case on a glass sheet to check for wobble does the same thing, but adds handling time.

If you measure a few primed cases, you will notice that the primer seating depths vary by several thou; this is not a problem in a rifle that has a good firing pin. Measure a few so your finger can get a 'feel' for what a few thou is, then put your caliper away. You can waste a lot of time measuring seating depths, with no noticeable benefit from an accuracy/performance point of view.

BTW, I don't bother uniforming primer pockets as I don't need the benefits of this procedure as my ammo is for hunting/practical shooting, not for tiny BR groups.

Safety: I find that it is important to be fully alert during the priming process as it is easy for a primer to end up upside down or sideways as you press it in.

Bushmaster · Posted: Sun Nov 30, 2008 7:09 pm Post subject: Re: Proper Primer Seating

Oh just seat the dang thing until they bottom out... When they stop moving you got it. If they are .001 or .002, or .003 or more (not to exceed .015), it really doesn't matter as long as they are seated to the bottom of the primer pocket.

I have NEVER measured the depth of my primers except with my finger tip...If they are below the case head you can feel it. wtf

ElyBoy · Posted: Sun Nov 30, 2008 11:25 pm Post subject: Re: Proper Primer Seating

Make it simple just like the gang says.
If you are getting complicated on the primers, I don't even want to know the hand wringing that is going on in your reloading room about the really important stuff.

Eric

Vince · Posted: Mon Dec 01, 2008 1:09 am Post subject: Re: Proper Primer Seating

Welcome to HuntingNut Lester. Grab a beer mate and pull up a stump. Feel free to ask a question or jump in with an answer...we are a happy go-lucky bunch of "Nuts" here, interlaced with a lot of experience and knowledge.

Like everyone else, I too just bottom the little buggers out...then do as Bushy says...feel it with my finger as I'm putting it back into the loading block.

I don't use a hand priming tool...I use my single stage press, as I have for 30 years, and I have never had a real problem unless I haven't cleaned the primer pockets as twofifty says. With my press and the priming arm, I actually get two distinct little "bumps" as the primer seats. If I don't feel those two "bumps" then I start looking for the reason why.

So Lester...are you anal...nah, you are just doing what each and every one of us have done, and still do, trying to produce the best possible handload that you can.

Cheers, Vince

wncchester · Member Joined: Apr 08, 2006 Posts: 160

"I seat primers till I feel them bottom out in the pocket period. Never have had a problem. I don't care if they are .003 or .005 below the cartridge base,.."

Me too. I only said what I did because he asked for specific measurements.

Seating by the measurments ain't "wrong" but I sure don't do it that way - any more! I did do it that way for awhile tho, until I gained confidence. Now my primers just get a quick swipe of my finger to confirm that I did in fact feel them hitting the pocket bottom as they should. Part of the learning curve.

Elvis · Posted: Wed Dec 03, 2008 8:18 pm Post subject: Re: Proper Primer Seating

I use a lee hand primer with tray seat them by feel. I cock up about 1 in 50 by not putting in deep enough or mashing it by it not being quite right I pull old betsy out the cupboard bang off the primer and run it back through to de prime, ream/debur pocket and poke a new one in. ps dont point the barrel into your good polarfleece top to suppress the bang when doing this as it leaves a wonderful wee burn!!!

ElyBoy · Posted: Wed Dec 03, 2008 9:15 pm Post subject: Re: Proper Primer Seating

I pulled a dandy two summers ago, and loaded up a box of .45 ACP's for my 1911.
Every one of them weren't seated properly, and I wanted to shoot.
My first pull of the trigger was a dud, but it seated the primer, so my second pull of the trigger, I knew would shoot.
I shot the whole box that way, and all of the guys at the Club were in stitches. wtf

I have a couple of revolvers that are real close tolerance between the cylinder and the frame, and that is when I become real anal about making sure that the primers are seated.

No caliper, just look and feel.

Eric

Bushmaster · Posted: Thu Dec 04, 2008 9:21 am Post subject: Re: Proper Primer Seating

Where'd you go Lesterg3? You still with us? I just hate when this happens. Seems we've been talking to thin air again... Very Happy

Well...I'm back. Been trying to call oorrork in eeurope, but couldn't seem to get that porcilen telephone to make contact... Sad

Handloader · Posted: Thu Dec 04, 2008 9:36 am Post subject: Re: Proper Primer Seating

Lachmiller, RCBS and others offer primer seating tools that seat to a pre-determined adjustable depth. The feel in seating primers is important and gives clue if something is amiss.

IMO/E, there is seldom a need to ever clean a primer pocket. The residue that comes out when cleaning is consistent whether the case has been fired once or multiple times which leads me to the conclusion that most pockets are self cleaning. Asking top competitors in benchrest or 600/1000 yard target shooting, I have found a divided opinion on whether the pockets need cleaning, but, many feel it is an unnecessary step. And they win their share of matches.