Primer seating depth

[FISHY-A-NADO]

Up until now, I have used my Lee Challenger press for all my primer seating and it is very consistent as far as seating depth goes. All the primers end up just below flush and look very much like factory originals.

Last night, I decided to use the Lee Auto-Prime and I noticed that while being a little quicker, the results were much less consistent. About half of the primers ended up considerably deeper...enough so that it is easily spotted with the naked eye---no close up examination necessary.

My fear is that this could lead to inconsistent performance, light strikes, FTFs, etc. so I am wondering if any others using the Auto-Prime have experienced this and what steps were taken to remedy the situation.

Or, could it be the brass has inconsistently sized primer pockets? It is nickel plated Federal .357 magnum and this is the second time I have loaded it.

As always, any input will be greatly appreciated.

[mehavey]

I went to (Lee) hand-priming for all of my work precisely because doing it
by "thumb-pressure" feel does give me exceptional consistancy in
bottoming out.

Exceptions are more likely due to primer pocket inconsistancy in your case.
In that event, a primer pocket uniformer (in a cordless drill) is a 1-time solution
-- or -- pick up some RP, Winchester, (etc) brass and check out the difference.

[Hammerhead]

My Winchester .357 brass has quite a bit of variation in pocket depth.

I was getting a few failures to fire now and then seating primers to a -.003" preset depth. I changed my Ram Prime to go by feel and primer depths were anywhere from -.001" to -.009", but no more misfires. In fact there were at least 5 or 6 cases out of 50 that had -.008" or -.009" deep primers, but no problems for my GP100.

[57K]

The spec for primer depth that goes back a few years is .006" below the rim. If you use a handheld priming tool, the primers should "bottom out" and be more like .010" below the rim. Deep seated primers do not cause ignition problems. High seated primers, on the other hand, are often a problem when a round fails to go off from the first hammer/stiker strike where all that occurs is the primer getting seated to its proper depth where a second strike ignites the primer and fires the round. Seat primers sufficiently and you're less likely to have a primer failure.

[mehavey]

Seat primers sufficiently and you're less likely to have a primer failure.

+1

Fully-seated up against the stop (to where the firing pin doesn't expend energy trying to seat it further upon striking it) is the most reliable position.

[FISHY-A-NADO]

As suggested, I pulled out some Winchester brass (.38 special this time) and took another stab at priming with the Lee Auto-Prime. While the depth was very consistent on this batch, I ran into a different problem with the tool.

I followed the instructions to the letter, but about every 5th or 6th attempt to prime a case resulted in some variation of a feeding problem, jam, or sideways seated primer (If I am holding it in the manner I understand the instructions to prescribe, I do not see the position of the primer before slipping the shell into the shell holder). After having to stop 3 or 4 times to clear the problem and put everything back together, I decided it was much faster and less aggravating to go back to priming on the press.

Do any of you have any tips or tricks I could try with the Auto-Prime to eliminate the issues? When it works, it works great but it's entirely too aggravating to have to clear it every half dozen cases or so.

[Mohave-Tec]

There is a small primer head and a large primer head. Which one are you using? Mine works every time.
I always clean primer pockets and I always bottom out primers. Never an issue in any of my guns.

[mehavey]

...every 5th or 6th attempt to prime a case resulted in some variation of a feeding problem,
jam, or sideways seated primer...

Literally "can't happen" (except in a blue moon).

As suggested above, are you using the proper small primer assembly in your trials?

[FISHY-A-NADO]

There is a small primer head and a large primer head. Which one are you using?

I am using the small primer tray with Winchester Small Pistol Primers.

Quote:
...every 5th or 6th attempt to prime a case resulted in some variation of a feeding problem,
jam, or sideways seated primer...

Literally "can't happen" (except in a blue moon).

Well then, there were 4 blue moons in my garage last night in the span of about 25 minutes.

Sine I am obviously using the proper tray for the primers I have, what else might I look at as a possible cause. I suspect that it must surely be my technique if it " "literally "can't happen" ". So if someone has better instructions than what came with the unit, your input would certainly be welcomed.

[mehavey]

I honestly don't know how the primers can get sideways other than in that proverbial Blue Moon.
Does looking at this video reveal anything that you might/might not be doing?
http://www.youtube.com/watch?v=7vfZM3gDjBc

[FISHY-A-NADO]

Thanks for the link Mehavey. Unfortunately, they have access to YouTube blocked here at work so I will have to wait until this evening to check it out.

I really hope I can figure it out. I like the concept of the Auto-Prime, but so far it has not been worth the aggravation.

[mikld]

Disregard any "measurements/dimensions" for primer depth. Just seat the primers all the way to the bottom of the primer pocket. If the anvil isn't seated to the bottom, giving some support, the primer prolly won't work. I have been reloading for many years and the only misfires were from primers seated too shallow, even though some did fit the "proper depth measurements". I haven't seen a gun with a firing pin that wouldn't hit the primer hard enough if it was seated at .010" below the head face, rather than .005" (not talking about an altered, unreliable gun's hammer, firing pin, etc.).

[Unclenick]

Originally Posted by 57K

The spec for primer depth that goes back a few years is .006" below the rim.

Actually that comes closest to being an old maximum. Forster relies on -0.005" for their Co-ax press's fixed depth tool as a compromise value, but the specifications given by Remington and Olin to the military in the 1970's is 0.002"-0.006" of "consolidation". That means, once the feet of the primer anvil touch the bottom of the primer pocket, you want an additional 0.002" to 0.006" of compression to set the bridge (the thickness of priming mix between the tip of the anvil and the bottom of the cup).

In the 1995 Precision Shooting Reloading Guide, Dick Wright wrote that he had contacted Federal for a more current recommendation, and they had suggested 0.002" beyond anvil contact for small primers, and 0.003" beyond anvil contact for large primers, specifically. The only tool I am aware of that measures this is the K&M Primer Gauge tool, which compensates both for variation in primer pocket depth and variation the height of individual primer anvils, but it is slow work using it and you have to be willing to put the time in if you want to be that exact. I use one for load development for the repeatability, but then look to see how much I lose by skipping the work and just using a fixed depth. In general, I don't find I see a difference unless the gun is for long range and is grouping about 3/8" or better. If you uniform the depth of your primer pockets, obviously that removes one of the variables a fixed seating depth setup will give you, be it the Forster Co-ax press built-in tool (their Co-ax bench priming tool does not have that feature), or the Sinclair tool can be adjusted to provide a fixed depth. It has the best feel of all tools I've tried.

This article, if the link hasn't changed again, will give you the lowdown on bridge setting and magnum vs. standard primers and other information. The one additional take-away apropos of this thread is that while Speer produced some brittle priming mixes in past decades, modern ones are not that way and will not be cracked by being squeezed down. Be aware, though, that this is not the same as saying they will ignite optimally at just any level of bridge squeeze.