Primer Seating Depth?

[wkdickinson]

OK, I understand, but don't quite accept the concept that a consistent primer seating depth "might" be better. What I have a problem with is, if the primer is not seated against the bottom of the pocket, how is that a good thing?

I've used my Sinclair "Primer Pocket Uniformer" many times to try and make my primer pocket depths consistent, but ultimately they aren't, or alt least they don't "seat" uniformly. So which is better - consistent depth or seated against the bottom of the pocket?

Wayne

 

[DHuffman]

They probably won't seat uniformly in part to the variance in primer cup height.
I've got my best results uniforming the pocket then seating the primer to bottom + a measured amount of crush, preload, tension or whatever people want to call it.

 

[ronemus]

There are tolerances in all of the components of a primer, even if the primer pockets are uniform. Primers are made of stamped brass, the priming compound is leveled by hand, and they are assembled by hand - there's lots of opportunity for tolerance stacking. At least some ammo manufacturers who make primers in-house seat primers while the pellet is still wet to avoid this issue.

 

[Coyotefurharvester]

If you don't seat to the bottom of the pocket , you risk a fail to fire.

 

[Straightshooter1]

OK, I understand, but don't quite accept the concept that a consistent primer seating depth "might" be better. What I have a problem with is, if the primer is not seated against the bottom of the pocket, how is that a good thing?

I've used my Sinclair "Primer Pocket Uniformer" many times to try and make my primer pocket depths consistent, but ultimately they aren't, or alt least they don't "seat" uniformly. So which is better - consistent depth or seated against the bottom of the pocket?

Wayne

Better???

. . . consistent seating crush against the bottom of the pocket.

But my efforts are to get both as consistent as possible and to do that one needs to have the appropriate tools to do that (e.g. like a seating tool with a hard stop, a tool that measures both pocket depth and seating depth) . . . how important depends a lot on the particular shooting discipline.

 

[6BRA]

Must be seated at bottom of pocket with x amount of crush...how can you do that? As with everything else in this sport, there are ways. $$$$$

 

[MSS]

I’ve been using the rcbs priming tool for years. I uniform the pockets and “crush to feel” ( I guess). I’ve never really thought too much about it. I just try to be consistent.

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[wkdickinson]

I seat primers using a Lee "Bench Prime" and i seat them until i feel the cup "bottom", so it stops - which obviously crushes the pellet. I just can't get my mind around the logic of any other strategy.

 

[JFrank]

You would be hard pressed to damage a primer,

 

[Jager]

I'm with you 100%, Wayne.

I'm in the camp who wants the primer seated so that the anvil has contacted the bottom of the primer pocket, and the feet of that anvil have been pressed ever so slightly into the cup, stressing the pellet of the priming compound. It goes without saying that the resulting primer must be a few thousandth's below the case head.

Seating to a set distance will result in tiny variations in how much each primer is pre-stressed, simply because of the inevitable manufacturing tolerances of primer cup height and primer pocket depth.

Only way I know of to achieve what I'm after is to prime by feel, with a hand tool, one at a time.

 

[NZ_Fclass]

I "acquired" a quantity of Russian primers recently. The only way I could seat them was the RCBS seating die on the old Rockchucker., They were too large to fit into the Dillon primer tubes. We'll see what happens - I'm only using the loads for sighting and running in a barrel.

 

[JFrank]

I use a hand primer with an adjustable cutter, lightly clean each pocket at the same depth, seat to the bottom and experimented with crush per click until I liked the results on paper with regards to consistency and felt fairly certain that I was well within the window of no harm.

Additional reading on the subject..vvv

21st Century Priming Tool

Hello, everyone. This is my 1st post, though I've been lurking around for some time. In keeping with the philosophy that the only dumb question is the one you don't ask, there is something about the capability of the 21st Century Shooting Priming Tool that confuses me. First of all, the...

forum.accurateshooter.com

 

[William Vogel]

I "acquired" a quantity of Russian primers recently. The only way I could seat them was the RCBS seating die on the old Rockchucker., They were too large to fit into the Dillon primer tubes. We'll see what happens - I'm only using the loads for sighting and running in a barrel.

I bought some of the Genex large rifle primers. I was going to test them out on some 308 rounds for my M1A but the first one I tried to seat was so tight in new brass I gave up. I seated two. I put them away and loaded with federal primers. The idea now is that I’ll try them again if the pockets get loose. I didn’t take the time to measure them for comparison. Kinda disappointed.

 

[NorCalMikie]

Bottom of the pocket. Nuff said!! Try seating a primer HIGH in an M1A and see what happens.
I use a Lee Auto Prime as beat up as it is but it still does the job.
Not sure how many thumb levers I've replaced/ gone thru but I've seated a BUNCH of primers over the years and my Auto prime is still going strong.
If you have a "high primer", you've got issues that need to be corrected.

 

[William Vogel]

Bottom of the pocket. Nuff said!! Try seating a primer HIGH in an M1A and see what happens.
I use a Lee Auto Prime as beat up as it is but it still does the job.
Not sure how many thumb levers I've replaced/ gone thru but I've seated a BUNCH of primers over the years and my Auto prime is still going strong.
If you have a "high primer", you've got issues that need to be corrected.

The #34’s I have seat deep. Below flush and I check every one with my finger before I set the case back in the loading block. The automatics are seated differently.

 

[mikecr]

Only way I know of to achieve what I'm after is to prime by feel, with a hand tool, one at a time.

This is the for-sure way to never get crush right. Maybe that's not what you want?
To set crush you need to account for pocket depth and primer height, while actually measuring your seating.
Once you've done this with a batch, you learn that it cannot be done by 'feel', anymore than you could seat boat tails slightly/consistently into donut area by feel.

 

[Alex Wheeler]

Primers want to be seated to a certain amount of depth past where they bottom out. When we tested this we found that when you seat them by feel you end up pretty much in the sweet spot. After doing my own testing and seeing others testing, I no longer uniform primer pockets and I seat primers by feel. You can have great results with other methods too. But I have seen nothing to make me believe uniforming the pockets or seating to a number will shoot smaller. In fact I think uniforming the pockets hurt my accuracy.

 

[Bill Norris]

Primers want to be seated to a certain amount of depth past where they bottom out. When we tested this we found that when you seat them by feel you end up pretty much in the sweet spot. After doing my own testing and seeing others testing, I no longer uniform primer pockets and I seat primers by feel. You can have great results with other methods too. But I have seen nothing to make me believe uniforming the pockets or seating to a number will shoot smaller. In fact I think uniforming the pockets hurt my accuracy.

I stopped uniforming primer pockets long ago. Seen no difference in group size without it.

 

[JFrank]

I stopped uniforming primer pockets long ago. Seen no difference in group size without it.

Man I’m glad y’all posted that, sure gives me additional confidence that I’m on a decent path.

 

[TylerFromMS]

I never understood cutting to a depth that the tool doesn't indicate off of. Seems like you'd need to sort the brass for a value from top of rim to bottom of primer pocket if you don't do it by feel.