Measuring primers
- Thread starter 06shooter
- Start date
I haven't measured a primer in mebbe 29 years. No don't measure the anvil as I don't believe there is a tolerance on the insertion of the anvil into the cup. I have measured cup height and diameter, just for fun. I think some like to "pre-load" the primer by seating to when the anvil hits bottom, then giving a bit more pressure to "pre-load"/"sensitize" the primer.
There are core hole plugs, freeze plugs and welch plugs, none are used in reloading. Anyone that is familiar with the use of the 3 plugs understands what happens when plugs are installed. The center is pushed up and the outside diameter is reduced.
Then there is that part about setting the primer. When a question is asked on the Internet about a failed to fire primer the answer is always "Did you set the primer?" "If you didn't the firing pin set it for you".
I have gone through a few failed to fire primers in loaded ammo, some had been struck 5 times with 3 different rifles, when chambered in one of my rifles with killer firing pins they all became once fired cases.
A few would think a primer that has been struck 5 times would be rendered scrap, always ware goggles.
F. Guffey
Then there is that part about setting the primer. When a question is asked on the Internet about a failed to fire primer the answer is always "Did you set the primer?" "If you didn't the firing pin set it for you".
I have gone through a few failed to fire primers in loaded ammo, some had been struck 5 times with 3 different rifles, when chambered in one of my rifles with killer firing pins they all became once fired cases.
A few would think a primer that has been struck 5 times would be rendered scrap, always ware goggles.
F. Guffey
Measuring primers? Done it only to see how much the anvil gets pushed up into the cup when seated. A few thousandths is normal. Compared it's flat distance below case head after measuring pocket depth and new primer dimension from anvil legs to its flat where the pin strikes it. Do it; it's interesting.
I've not seen any accuracy difference between primer pockets uniformed for depth and not uniformed as long as the primer's seated to the same level of tactile feedback force on hand held seating tools. Primers are not all exactly the same depth below flush with the case heads but vary a couple thousandths.
Primers tend to be more consistent with some preload force that's fairly consistent as well as struck hard enough to detonate them the same for each shot. Firing pin springs need to be at factory spec force (or a few pounds more) when cocked. The pin tip should protrude from the bolt face about .060" at its full protrusion past it for large rifle primers.
I've not seen any accuracy difference between primer pockets uniformed for depth and not uniformed as long as the primer's seated to the same level of tactile feedback force on hand held seating tools. Primers are not all exactly the same depth below flush with the case heads but vary a couple thousandths.
Primers tend to be more consistent with some preload force that's fairly consistent as well as struck hard enough to detonate them the same for each shot. Firing pin springs need to be at factory spec force (or a few pounds more) when cocked. The pin tip should protrude from the bolt face about .060" at its full protrusion past it for large rifle primers.
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4runnerman
New member
Bart-Question- I have heard from a few( Bench shooters). They always use a hand press for seating primers ( easier to set them all the same) Also ( If I remember right). Most Factory springs are set at 28 lbs. They also say to bump up to a 32 lb spring and to set protrusion back to .050. Now I have done this on my Rifle and really have not noticed any real difference. I never have failure to fire,but it seems I did all this for no real gain.
Yes, hand seaters tend to be best. If used right. One may not see any difference unless they're used in sub 1/3 MOA rifles at 100 yards.
I've heard small rifle primers are OK with .050" protruding pin tips. The Rem 7.5 BR primers in my Rem .308 BR cases did well in my rifles with .060" pin protrusions.
www.gunsprings.com lists spring specs for all sorts of firearms. Win 70 specs are 23 pounds but I and many others use 26 pound ones.
One of the guys at a Palma match asked me if I had a spare spring for his Win 70 because his long range groups were stringing way too much vertically on practice day. I gave him a new 26 pound one then he won the match the next day.
I've heard small rifle primers are OK with .050" protruding pin tips. The Rem 7.5 BR primers in my Rem .308 BR cases did well in my rifles with .060" pin protrusions.
www.gunsprings.com lists spring specs for all sorts of firearms. Win 70 specs are 23 pounds but I and many others use 26 pound ones.
One of the guys at a Palma match asked me if I had a spare spring for his Win 70 because his long range groups were stringing way too much vertically on practice day. I gave him a new 26 pound one then he won the match the next day.
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Another great Guffy post. But, I can't see the connection between freeze plugs
and the question; "When measuring primers do you include the anvil?". The plugs mentioned close/seal a hole for a particular reason. A primer is a component inserted into a receptacle in another component for the purpose of igniting the enclosed powder...
Mikld,
Mr. Guffey is explaining, by analogy, the effect on the geometry of the primer cup inserted into a primer pocket. It's one of the considerations primer makers will use in balancing cup diameter and anvil protrusion. It is allowed for in the seating recommendations.
There are, in fact, some published primer seating tolerances. How far you compress the anvil is called setting the bridge (of priming mix between the cup and anvil), by Alan Jones, in this article, and is called reconsolidation in this report by McDonnell Douglas on primer use. At the time of the report, Olin and Remington (see last three illustrations, in particular, as the others are special high temperature primers). Their recommendations are 0.002-0.006" of reconsolidation, meaning that's how much the anvil was pressed down into the priming mix.
That specification is what the Forster Co-ax press's bulit-in primer seater tool is based on. It pushes the primer 0.005" below flush with the case head, expecting about 0.001" of spring-back, so the primer winds up 0.004" below flush. It is premised on primer pocket depth being equal to the average height of the primer, including the anvil, before seating.
In 1994, John Feamster got a recommendation from Federal for their primers of 0.002" of reconsolidation for small rifle primers and 0.003" for large rifle primers. Federal is, AFAIK, the only major primer manufacturer using the hydroxide of lead styphnate rather than straight lead styphnate as their sensitizer, and this may account for the difference.
The above doesn't always work out in practice. I've had some primers whose anvils stuck out a lot further than others. The McDonnel-Douglas report refers to selecting primers with anvils so high that just seating them flush did adequate reconsolidation, finding that a convenient way to seat primers for some devices.
06shooter,
Since the anvil makes contact with the bottom of the primer pocket before the end of the primer cup, you measure primer height to include the anvil. Subtract the depth of your primer pocket from the height of your primer, then subtract your desired reconsolidation squeeze from the result. The final number is how far below flush with the case head the primer will be when you have the desired reconsolidation. Normally you will end up with a number that is about -0.004", but the exact result does depend on how far above the cup the primer manufacturers set the anvils.
There is a special primer seating tool made by K&M that measures the depth of individual primer pockets, for those not uniforming them, and the height of the individual primer that is to be inserted in that pocket, and zeroes a seating depth gauge against the individual values. When you actually seat the primer, the gauge shows zero when the anvil feet are kissing the floor of the primer pocket, and each thousandth of consolidation is then measured as a thousandth past zero on the indicator dial.
Most folks don't go to this much trouble, and many will likely dismiss the need for such. Dick Wright wrote in 1995 that he didn't have the patience to take all the necessary steps, so he'd given up and was seating by feel, using, I think, the Sinclair tool whose design was inspired by Creighton Audette's suggestions. However, he also mentioned that his wife was continuing to use the tool, and that she was beating him at most benchrest matches they were attending at that time.
I don't really have the patience, either, for most loading. I do, however, own one of the primer gauge tools, and use it when trying to make loads with, as near as I can, zero variables to serve as a comparison standard during load development. For just the 20 rounds to be fired in the long range phase of a match, it's not too bad, either.
But for most shooters, rather than measuring carefully and checking all this stuff, I think Dan Hackett's advice probably is the easiest to follow:
Mr. Guffey is explaining, by analogy, the effect on the geometry of the primer cup inserted into a primer pocket. It's one of the considerations primer makers will use in balancing cup diameter and anvil protrusion. It is allowed for in the seating recommendations.
There are, in fact, some published primer seating tolerances. How far you compress the anvil is called setting the bridge (of priming mix between the cup and anvil), by Alan Jones, in this article, and is called reconsolidation in this report by McDonnell Douglas on primer use. At the time of the report, Olin and Remington (see last three illustrations, in particular, as the others are special high temperature primers). Their recommendations are 0.002-0.006" of reconsolidation, meaning that's how much the anvil was pressed down into the priming mix.
That specification is what the Forster Co-ax press's bulit-in primer seater tool is based on. It pushes the primer 0.005" below flush with the case head, expecting about 0.001" of spring-back, so the primer winds up 0.004" below flush. It is premised on primer pocket depth being equal to the average height of the primer, including the anvil, before seating.
In 1994, John Feamster got a recommendation from Federal for their primers of 0.002" of reconsolidation for small rifle primers and 0.003" for large rifle primers. Federal is, AFAIK, the only major primer manufacturer using the hydroxide of lead styphnate rather than straight lead styphnate as their sensitizer, and this may account for the difference.
The above doesn't always work out in practice. I've had some primers whose anvils stuck out a lot further than others. The McDonnel-Douglas report refers to selecting primers with anvils so high that just seating them flush did adequate reconsolidation, finding that a convenient way to seat primers for some devices.
06shooter,
Since the anvil makes contact with the bottom of the primer pocket before the end of the primer cup, you measure primer height to include the anvil. Subtract the depth of your primer pocket from the height of your primer, then subtract your desired reconsolidation squeeze from the result. The final number is how far below flush with the case head the primer will be when you have the desired reconsolidation. Normally you will end up with a number that is about -0.004", but the exact result does depend on how far above the cup the primer manufacturers set the anvils.
There is a special primer seating tool made by K&M that measures the depth of individual primer pockets, for those not uniforming them, and the height of the individual primer that is to be inserted in that pocket, and zeroes a seating depth gauge against the individual values. When you actually seat the primer, the gauge shows zero when the anvil feet are kissing the floor of the primer pocket, and each thousandth of consolidation is then measured as a thousandth past zero on the indicator dial.
Most folks don't go to this much trouble, and many will likely dismiss the need for such. Dick Wright wrote in 1995 that he didn't have the patience to take all the necessary steps, so he'd given up and was seating by feel, using, I think, the Sinclair tool whose design was inspired by Creighton Audette's suggestions. However, he also mentioned that his wife was continuing to use the tool, and that she was beating him at most benchrest matches they were attending at that time.
I don't really have the patience, either, for most loading. I do, however, own one of the primer gauge tools, and use it when trying to make loads with, as near as I can, zero variables to serve as a comparison standard during load development. For just the 20 rounds to be fired in the long range phase of a match, it's not too bad, either.
But for most shooters, rather than measuring carefully and checking all this stuff, I think Dan Hackett's advice probably is the easiest to follow:
"There is some debate about how deeply primers should be seated. I don’t pretend to have all the answers about this, but I have experimented with seating primers to different depths and seeing what happens on the chronograph and target paper, and so far I’ve obtained my best results seating them hard, pushing them in past the point where the anvil can be felt hitting the bottom of the pocket. Doing this, I can almost always get velocity standard deviations of less than 10 feet per second, even with magnum cartridges and long-bodied standards on the ’06 case, and I haven’t been able to accomplish that seating primers to lesser depths."
Dan Hackett
Precision Shooting Reloading Guide, Precision Shooting Inc., Pub. (R.I.P.), Manchester, CT, 1995, p. 271.
Dan Hackett
Precision Shooting Reloading Guide, Precision Shooting Inc., Pub. (R.I.P.), Manchester, CT, 1995, p. 271.
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Dan Hackett's method has been repeated in different ways for decades. Thanks Nick, for posting it.
In measuring the amount anvil legs are below large rifle primer cup bottoms, the anvil legs seat about .004" to .005" deeper to be flush with the cups's bottom edge. That's given me minimal vertical shot stringing and best accuracy at all ranges. It must preload (reconsolidate) the primer compound good for uniform performance. I think there's been articles in other forums saying the same thing, essentially; seat primer cups against their pocket's bottom.
In measuring the amount anvil legs are below large rifle primer cup bottoms, the anvil legs seat about .004" to .005" deeper to be flush with the cups's bottom edge. That's given me minimal vertical shot stringing and best accuracy at all ranges. It must preload (reconsolidate) the primer compound good for uniform performance. I think there's been articles in other forums saying the same thing, essentially; seat primer cups against their pocket's bottom.
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there is no shortage of primer installing equipment around here. I loaned two RCBS auto hand primers to another reloader. He was having trouble with the half moon dent. With the RCBS auto hand primers I sent RCBS shell holders for 9mm. During this time he was working with RCBS, RCBS sent him custom made parts, they sent him enough parts to build another hand primer, when they ran out of ideals they sent him another 9mm shell holder.
Start over: The dent in the bottom of the primer, sometimes referred to as 'half moon' does not bother me, I have never had one fail to fire. If the dent in my primers bothers someone it bothers them more than it does me. The point? It is nothing personal, he had access to three hand primers and they all dented the primers.
I called RCBS, I thought I could offer insight, they were familiar with the effort made to correct the reloaders problem with dents. And then, they offered to sent me a 9mm shell holder
I did not need another 9mm shell holder so I thanked them for the effort.
the other reloader went back to using the Lee auto hand primer. I use Federal primers, getting Federal primers to fit the Lee hand primer was never a problem.
F. Guffey
Start over: The dent in the bottom of the primer, sometimes referred to as 'half moon' does not bother me, I have never had one fail to fire. If the dent in my primers bothers someone it bothers them more than it does me. The point? It is nothing personal, he had access to three hand primers and they all dented the primers.
I called RCBS, I thought I could offer insight, they were familiar with the effort made to correct the reloaders problem with dents. And then, they offered to sent me a 9mm shell holder
I did not need another 9mm shell holder so I thanked them for the effort.the other reloader went back to using the Lee auto hand primer. I use Federal primers, getting Federal primers to fit the Lee hand primer was never a problem.
F. Guffey
Reloader270
New member
I also had the half moon dents from a Hornady Hand Prime. I replaced it with an RCBS and never had it again.
JeepHammer
Moderator
With this Dillon 650, primers smashed a little flat (just sometimes) is an issue.
I first freaked out, coming from accuracy shooting,
But in the last two years with this thing, I've not had one fail to fire even though the 'Dome' was virtually flat...
(Knock Wood!)
It's been a LONG TIME since I got in new brass,
Then sorted them by primer pocket depth/diameter.
I don't miss it...
Cranking out these generally about MOA rounds is MUCH easier than trying to make a little hole just a little darker and a little more 'Fuzzy' around the edges,
And these ARs, common bolt rifles are a TON more fun to shoot when you aren't swabbing the barrel every round, or every 5 rounds...
Having a rifle that doesn't weight as much as my dog,
Not having to set up half a gun shop around your shooting position...
All less work and more fun!
NOW! If I can just figure out how my spent primers are winding up in the walnut media...
Don't have that issue with the new press, but the old hand press scattered them EVERYWHERE and two years later I'm still finding them in the strangest places!
I first freaked out, coming from accuracy shooting,
But in the last two years with this thing, I've not had one fail to fire even though the 'Dome' was virtually flat...
(Knock Wood!
)It's been a LONG TIME since I got in new brass,
Then sorted them by primer pocket depth/diameter.
I don't miss it...
Cranking out these generally about MOA rounds is MUCH easier than trying to make a little hole just a little darker and a little more 'Fuzzy' around the edges,
And these ARs, common bolt rifles are a TON more fun to shoot when you aren't swabbing the barrel every round, or every 5 rounds...
Having a rifle that doesn't weight as much as my dog,
Not having to set up half a gun shop around your shooting position...
All less work and more fun!
NOW! If I can just figure out how my spent primers are winding up in the walnut media...
Don't have that issue with the new press, but the old hand press scattered them EVERYWHERE and two years later I'm still finding them in the strangest places!
4runnerman
New member
And these ARs, common bolt rifles are a TON more fun to shoot when you aren't swabbing the barrel every round, or every 5 rounds...
Having a rifle that doesn't weight as much as my dog,
Not having to set up half a gun shop around your shooting position...
All less work and more fun!
Jeep- Say it aint so, say it aint so
When you take this all away now you only shoot for 4 hrs instead of 8 
Whats the fun if it aint 5 trips from the truck to the bench to unload and load., $30.00 in patches and solvents a month, countless hrs trimming,weighing, sorting,turning,ect ect. It's not right to have that much fun and shoot too. There must be some kinda law against it.
Having a rifle that doesn't weight as much as my dog,
Not having to set up half a gun shop around your shooting position...
All less work and more fun!
Jeep- Say it aint so, say it aint so
When you take this all away now you only shoot for 4 hrs instead of 8 Whats the fun if it aint 5 trips from the truck to the bench to unload and load., $30.00 in patches and solvents a month, countless hrs trimming,weighing, sorting,turning,ect ect. It's not right to have that much fun and shoot too. There must be some kinda law against it.
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06shooter,
I'm assuming you are talking about firing pin pocket depth. It should be fine if you have normal firing pin protrusion. Remington's spec is -0.127±0.001" for primer pockets on new brass (pockets get shallower with successive firing due to the floor of the primer pockets being bulged out by pressure).
I measured several different makes of cases with a depth micrometer that has a flat ground and polished tip 0.1875" (3/16") diameter. I got a range from -0.1265" to -0.1292". It varied a little by brand. A new Winchester case I measured at -0.1280" read -0.1290" using the depth probe of my caliper, and that took some care. The caliper is a clumsy tool for this, and I got readings as high as -0.135" with it. In the end, the way I got 0.129" consistently was to move the depth probe out and dangle the head so the depth probe was pointing up in the air, then bringing the case down on it and carefully bringing it to flat against the back end of the beam. But still, it was off by -0.001"; about as good as that end of the tool is.
The bottom line is, if you measured -0.132" it with a caliper, don't be too comfortable about the number you are getting being accurate. The best way is with a depth micrometer as it will average the surface of the head better and be square to it. If these cases have been cut with a depth uniforming tool, then the -0.132" number may be good, if a bit deeper than I'd expect, but it should still work.
I'm assuming you are talking about firing pin pocket depth. It should be fine if you have normal firing pin protrusion. Remington's spec is -0.127±0.001" for primer pockets on new brass (pockets get shallower with successive firing due to the floor of the primer pockets being bulged out by pressure).
I measured several different makes of cases with a depth micrometer that has a flat ground and polished tip 0.1875" (3/16") diameter. I got a range from -0.1265" to -0.1292". It varied a little by brand. A new Winchester case I measured at -0.1280" read -0.1290" using the depth probe of my caliper, and that took some care. The caliper is a clumsy tool for this, and I got readings as high as -0.135" with it. In the end, the way I got 0.129" consistently was to move the depth probe out and dangle the head so the depth probe was pointing up in the air, then bringing the case down on it and carefully bringing it to flat against the back end of the beam. But still, it was off by -0.001"; about as good as that end of the tool is.
The bottom line is, if you measured -0.132" it with a caliper, don't be too comfortable about the number you are getting being accurate. The best way is with a depth micrometer as it will average the surface of the head better and be square to it. If these cases have been cut with a depth uniforming tool, then the -0.132" number may be good, if a bit deeper than I'd expect, but it should still work.
Thanks Mr.Nick ! I really don't like to be"worry some " about this but I would like to get it right.
I've researched rcbs, Lyman , and Sinclair, they don't give the depths they cut to. Rcbs said .132 " when I called .
Are they designed to cut a slight cone shape ? , I ask because my rcbs uniformer is taller at the center point than at the outer edge . After uniforming, I do not get .132" .
My uniformer bottoms out on a Rem. once fired brass.
It does not with new Nosler or Win.
I seated a WLR into the rem. case very slowly to feel for the stop , I measured and the best I got was .004" below flush .
Yes those calibers are very tricky , but those micrometers are expensive!
Should the anvil become flush for a good
My firing firing pin protrudes at .060" the best I could measure.
I have learned a lot so far , just need to fill in the pieces
Thanks
I've researched rcbs, Lyman , and Sinclair, they don't give the depths they cut to. Rcbs said .132 " when I called .
Are they designed to cut a slight cone shape ? , I ask because my rcbs uniformer is taller at the center point than at the outer edge . After uniforming, I do not get .132" .
My uniformer bottoms out on a Rem. once fired brass.
It does not with new Nosler or Win.
I seated a WLR into the rem. case very slowly to feel for the stop , I measured and the best I got was .004" below flush .
Yes those calibers are very tricky , but those micrometers are expensive!
Should the anvil become flush for a good
My firing firing pin protrudes at .060" the best I could measure.
I have learned a lot so far , just need to fill in the pieces
Thanks