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Noob question about primer seating depth
https://www.waguns.org/viewtopic.php?f=74&t=83258
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Author:  delliottg [ Sat Jul 29, 2017 9:21 pm ]
Post subject:  Noob question about primer seating depth

So, up until now, I've been using a Lee hand primer, but with arthritic hands it got painful to do more than a few primers and it hurt the whole time mashing the lever to the point where I had to use both hands to do it. So I bought a Lee Auto Bench Prime and initial results are good-ish, I think. My question is, after priming several dozen cases, I haven't yet developed the feel for how deep to seat the primer, and a large number of them have their primers seated a couple hundredths low (0.02") according to my calipers. The instructions in the Lee booklet seem to indicate that this is OK, as in "slightly low".

What do you guys think?

Author:  MadPick [ Sat Jul 29, 2017 9:27 pm ]
Post subject:  Re: Noob question about primer seating depth

Seat 'em as far as they'll go.

Author:  PMB [ Sat Jul 29, 2017 9:31 pm ]
Post subject:  Re: Noob question about primer seating depth

I seat primers by feel, not by metrics. So far never had an issue with primer depth that way.

Author:  reginald_burrito [ Sat Jul 29, 2017 9:32 pm ]
Post subject:  Re: Noob question about primer seating depth

I'm not aware of primer depth having any affect on pressures. I wouldn't worry about it unless you're seeing reliability problems like light strikes or primers backing out.

Author:  PMB [ Sat Jul 29, 2017 9:33 pm ]
Post subject:  Re: Noob question about primer seating depth

MadPick wrote:
Seat 'em as far as they'll go.

And then take a small punch and give 'em a whack with a hammer to make sure they're in all the way.

Author:  Sinus211 [ Sat Jul 29, 2017 9:35 pm ]
Post subject:  Re: Noob question about primer seating depth

MadPick wrote:
Seat 'em as far as they'll go.


Agreed. I seat the primers deeper than the case rim. I like to feel the bell smash out and really grab. I might be doing it wrong but haven't ever had an issue with them being loose or having any light strikes. Err on the side of caution means really get that primer in there, in my experience.

Author:  velillen [ Sat Jul 29, 2017 9:54 pm ]
Post subject:  Re: Noob question about primer seating depth

I seat mine by feel. Whether using the dillon 550b or the RCBS hand primer. I go till you start feeling a large jump in resistance. Youll notice youll apply the same amount of pressure then all of a sudden you have to press harder. I pretty much stop there. As for the depth i just checked a few different calibers and its all over the place (really within a few thousandths but looks more). 32acp is slightly above (1-2 thousandths), 308 is pretty much flush, 458 socom is a fair amount down, 223 is flush, you get the idea :)

Author:  AR15L [ Sun Jul 30, 2017 5:57 am ]
Post subject:  Re: Noob question about primer seating depth

PMB wrote:
MadPick wrote:
Seat 'em as far as they'll go.

And then take a small punch and give 'em a whack with a hammer to make sure they're in all the way.

Image

Author:  GeekWithGuns [ Sun Jul 30, 2017 5:58 am ]
Post subject:  Re: Noob question about primer seating depth

On pistol cases I do the seating on my LnL AP progressive, let the press do the work.

On match rounds (22 Hornet, 7mm Rem BR, 7mm TCU) I do all the seating by hand using a 21st Century hand priming tool which allows for seating depth adjustment. I normally seat to flush or just a hair under flush. Very little resistance involved in the seating process.

Are you having any ignition problems? This all really depends on your gun, firing pin length, and how light the action and firing pin impact are. Chances are .002" low won't really make any difference in getting reliable ignition but your range testing is the proof in the pudding.

One related topic to consider may be purchase of a case prep tool, whether automated or hand tools:
- Primer pocket uniforming for uniform depth & burr removal for easier seating
- Flash hole uniforming for more consistent powder ignition

I would only recommend this for round where accuracy is at a premium (i.e. would never do this for volume pistol rounds).
These operations need only be done once when prepping new cases though if you're really OCD and working up benchrest rounds you might want to periodically clean carbon deposits out of the primer pockets. Most likely not really worth it though.

Author:  jukk0u [ Sun Jul 30, 2017 8:22 am ]
Post subject:  Re: Noob question about primer seating depth

LEE hand primer machines are JUNK! They fracked the dog designing that thing as the ergos suck and the leverage advantage wasn't fully utilized. Makes them really difficult to squeeze IMO.

If you are going to stay with hand priming tools go with the RCBS one. (SageWA swears that the older ones are better than the new, but I don't know why)

edit: oh yeah. Just seat them so that they are flush or below the case rim and you're golden. and wear eye pro.

Author:  delliottg [ Sun Jul 30, 2017 8:39 pm ]
Post subject:  Re: Noob question about primer seating depth

Thanks for all the answers guys!

Author:  noylj [ Wed Aug 02, 2017 9:53 am ]
Post subject:  Re: Noob question about primer seating depth

If there was a number, it would be in your reloading manuals and they would be selling tools to achieve it.
Sorry, "below flush" is good enough for even the most die-hard shooters.

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