Thread: Primer question

In terms of your first question: I've tried but found the primers to be a bit loose when seating in another case.
Second question: Probably not, but give it a go and let us know.

Originally Posted by buzzman

Silly question but got asked by a mate and had never thought about it , can you decap a live primer and reuse it? Cheers


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Answer from me is yes as I have done exactly that many times, always with commercial, large rifleboxer primers, standard and magnum. Always worn safety specs whilst doing but never had one ignite. Also have reprimed cases and shot rounds with these same primers. Worked as expected. Wouldn't have a clue as to whether depriming and repriming affected performance at all but what I tend to do with deprimed primers now is keep them aside for use in fouling and / or non-critical loads.

Maybe if you hunt Lions and Elephants it would pay not to re load them, but for targets etc they will be good to go. As said they seat a little soft due to being already seated once, but if your brass is good still...have at it (with due caution).

I have had two bangs but only when priming, never with depriming livies. When it goes and you have a full tube of primers you are expecting more bang for you buck thankfully that didnt happen. But it does make me reach for the earmuffs and safety specs.
Both occassions was pistol primers so maybe something in the fact they are thinner skinned.

Originally Posted by johnd

I have had two bangs but only when priming, never with depriming livies. When it goes and you have a full tube of primers you are expecting more bang for you buck thankfully that didnt happen. But it does make me reach for the earmuffs and safety specs.
Both occassions was pistol primers so maybe something in the fact they are thinner skinned.

Yep they are 'more sensitive' by design due to the smaller area for spring power to live in, in the frame of a pistol. Priming using the hand primers is a way to prevent pops over priming in a press where you have a lot more mechanical advantage (or with some presses anyway).

Not so much more sensative but a thinner cup. Typically 17 thou versus SR primers at 20 - 25 thou.
I use SP primers in my Hornets and get better results than with SR which have a stronger spark.
There is a risk of puncturing a primer though.

Originally Posted by zimmer

Not so much more sensative but a thinner cup. Typically 17 thou versus SR primers at 20 - 25 thou.
I use SP primers in my Hornets and get better results than with SR which have a stronger spark.
There is a risk of puncturing a primer though.

You are right, hence the '' around the more sensitive bit. By way of explanation for anyone not aware of how this works, the thinner cup means less force is required to get the necessary amount of crush of the priming compound between the primer's cup and anvil to successfully initiate priming compound burn when the firing pin is released. It also makes pistol primers easier to initiate during handling, or easier to ignite through improper priming techniques. When primers are shipped the anvil is not pressed home inside the primer cup, this is a way of desensitising the primers during shipping. When we prime cases, we squish the anvil back into the primer cup and against the priming compound layer inside the cup and this sensitises the primer ready for initiation by the firing pin. It's also why pistol primers are easier to ignite accidentally over other grades of primer and why pistol primers are considered easier to pierce when used in rifles but are also considered to have more reliable ignition characteristics.

Is that another way of depriming

Originally Posted by blip

Is that another way of depriming

Indeed. Also an excellent but noisy laxative.

Ah, almost right. CCI for example have the anvil petals sticking out. With RWS the anvil is flush with the bottom edge of the cup so you cannot preload them or push the anvil back in. With early Murom it was essential to drive the anvil in against the compound. If you didn't there was chances of erratic ignition or no bang at all. Don't know if Murom are still like that.
My practice for target ammo is to preload my BR4s by 1 1/2 thou and BR2s 2 thou preload. You cannot do that with normal priming tools. I currently use a Primal Rights tool. For sporting ammo I just seat by feel with a hand tool.

There is always the risk of overdoing it and crushing the primer material.

Before I started taking care priming I measured some of my early efforts done with an RCBS tool, carefully I thought. All primers were over seated and crushed.

One of the biggest priming issues, and I see the advise on the net, is to seat primers flush with the case base.

Originally Posted by zimmer

Before I started taking care priming I measured some of my early efforts done with an RCBS tool, carefully I thought. All primers were over seated and crushed.

One of the biggest priming issues, and I see the advise on the net, is to seat primers flush with the case base.

Curious about the last sentence here, I have a way by which I can seat flush with the case base but keen to know if that is an issue in itself or if the issue is in achieving said outcome.
For me, the jury is still out as to whether seating flush with the case base is the way to go.

Originally Posted by longshot

Curious about the last sentence here, I have a way by which I can seat flush with the case base but keen to know if that is an issue in itself or if the issue is in achieving said outcome.
For me, the jury is still out as to whether seating flush with the case base is the way to go.

Primer pockets like the cases themselves (well USA ones) are governed by SAAMI specs ie a maximum and a minimum value provided for primer pocket depths for manufacturers to work to. Primers vary between brands in over all length. Maybe even between batches. You could have a primer pocket at the deepest end of the SAAMI spec (still within spec) and a primer that is shortish. Outcome if seating flush is the bottom of the primer may not be correctly in contact with the bottom of the primer pocket which can lead to erraric ignition or no ignition.

I'd have to rechech SAAMI but I think these are the specs/tolerances -
Large Rifle PP specs 125 thou to 132 thou.
Large Rifle Primer specs 123 thou to 136 thou
So a 123 thou primer seated in a 132 thou pocket, flush, will not be a good combination.

The other thing that happens is if you uniform your primer pockets with for example a Sinclair tool, which is non adjustable, you may cut your pockets too deep. I had that happen with a Sinclair tool which before I realised it was cutting my pockets to 132 thou whereas I wanted 128 thou. IIRC 132 thou is still within SAAMI spec or right on it. They refunded me for that tool.

Originally Posted by zimmer

Primer pockets like the cases themselves (well USA ones) are governed by SAAMI specs ie a maximum and a minimum value provided for primer pocket depths for manufacturers to work to. Primers vary between brands in over all length. Maybe even between batches. You could have a primer pocket at the deepest end of the SAAMI spec (still within spec) and a primer that is shortish. Outcome if seating flush is the bottom of the primer may not be correctly in contact with the bottom of the primer pocket which can lead to erraric ignition or no ignition.

I'd have to rechech SAAMI but I think these are the specs/tolerances -
Large Rifle PP specs 125 thou to 132 thou.
Large Rifle Primer specs 123 thou to 136 thou
So a 123 thou primer seated in a 132 thou pocket, flush, will not be a good combination.

The other thing that happens is if you uniform your primer pockets with for example a Sinclair tool, which is non adjustable, you may cut your pockets too deep. I had that happen with a Sinclair tool which before I realised it was cutting my pockets to 132 thou whereas I wanted 128 thou. IIRC 132 thou is still within SAAMI spec or right on it. They refunded me for that tool.

I have always believed that to be the most important objective of seating primers ( i.e. seating to the bottom of the cup ), for certain and consistent ignition. To me, secondary and almost as important is to have primers flush with or just under the case head surface. Just so if cartridges are moving under recoil in the magazine there is no chance of the primer being contacted by any surface or projection.

Originally Posted by zimmer

Primer pockets like the cases themselves (well USA ones) are governed by SAAMI specs ie a maximum and a minimum value provided for primer pocket depths for manufacturers to work to. Primers vary between brands in over all length. Maybe even between batches. You could have a primer pocket at the deepest end of the SAAMI spec (still within spec) and a primer that is shortish. Outcome if seating flush is the bottom of the primer may not be correctly in contact with the bottom of the primer pocket which can lead to erraric ignition or no ignition.

I'd have to rechech SAAMI but I think these are the specs/tolerances -
Large Rifle PP specs 125 thou to 132 thou.
Large Rifle Primer specs 123 thou to 136 thou
So a 123 thou primer seated in a 132 thou pocket, flush, will not be a good combination.

The other thing that happens is if you uniform your primer pockets with for example a Sinclair tool, which is non adjustable, you may cut your pockets too deep. I had that happen with a Sinclair tool which before I realised it was cutting my pockets to 132 thou whereas I wanted 128 thou. IIRC 132 thou is still within SAAMI spec or right on it. They refunded me for that tool.

Thanks for getting back to me on that one, a good example for me of you don’t know what you don’t know.

Interesting thread.
I tested some primers on behalf of someone suffering misfires, who wanted to prove the primer or his gun, I didn't have the gun, or equivalent caliber so deprimed 10 cases in question and seated the primers in a cartridge I could dry fire. They all went bang at the squeeze of the trigger.
So to my experience it can be done, but as others have noted, probably best for range rounds as opposed to hunting rounds.