Does primer seating depth matter

[mikecr]

If by 'harming' primer performance, you mean interfere with it's basic function, I agree.
Primers WILL reliably ignite while near or hard into pocket bottom.
For some cartridges that's all you need, and it would be difficult to see differences otherwise.
I constantly see sentiments here & everywhere else that primers and seating doesn't matter.
Just grab any, seat em any way reasonably right,, they'll go bang.

But with most cartridges we can see a difference. We can swap primers today and absolutely see a difference -even while they're all firing. You might wonder why that is, I don't know why myself.
In my mind it seems like there should be no difference with one primer firing over another.
If different, then by now, why haven't we settled to the same SR or LR primers for common cartridges?

I just breezed over a log of load development for my son's gun, a Cooper in 223Rem.
-I started off with CCI450s, couple bullet changes, and quickly hit on a 3/8moa load, but chased flyers.
-I changed to BR4s, better group shaping, but still flyers here & there.
-I found that BR4s needed 5thou crush (instead of my normal 2thou setting), to remove flyers.
-Everything worked good for a while, the gun won a local/annual accuracy contest, killed many GHs.
-Year later, accuracy contest, knocked out in 4th round with a flyer (broken ugly kind).
-It took a month to figure out, got lucky with a misfire, my firing pin was slipping in it's cocking piece.
-I swapped to Fed205s(at 2thou crush), to hell with CCIs, and did full testing with different released firing pin settings. I seen groups open close open, similar to bullet seating. 1/8moa gain here.
-I modified the pin for permanent optimum pin setting (with Fed205s).
-I tried WSR primers for some reason, with Fed optimum striking, not as good.
-Back to Feds, end of log (no issue since). Solid 1/4moa/500yds varmint gun.

I bring this one up because it's a case where I chased my tail with primers, and there were differences.
I will always wish that I had slowed down to learn more about primers and the setting of striking that I engaged in. I really suspect that there was never anything wrong with CCIs for the load. That I just did not apply optimum striking for them.
I have tested different crush settings with primers in other cartridges, and found that FED, WIN, REM, RUSSIAN, prefer 2thou (and no more), while CCI prefers 5thou at least.

Mostly I wonder why supposed experts, who manufacture primers, have not defined optimum striking for their products, and put that information out.
There, I suspect that WE are the people who figure stuff out (not manufacturers).

 

[Jerry Wick]

@mikecr When you refer to "optimum pin setting" are saying that you adjusted firing pin fall?

If so, what measurement did you settle on for that particular rifle?

 

[J.d. Popkes]

I think he may be correct but their is to much opinion on internet. He said he shoots competition. If I shoot groups like his for a varmint hunting rifle I would junk the rifle. The easy way is to just do it like the guys that set National Records and forget the details.

I’m pretty sure he can shoot pretty okay.

 

[TTE]

Nice images. Looks like your limited to the cup edge touches the case. You cannot push it any deeper because you cannot crush/compress the cup itself. I am getting tired of all the primer talk. Do we need 100's of post every year explaining the same thing.

The posted video was not intended to be a "this is how I do it " thread. It was to gather comments on the content of the video ...... if primer seating depth made/makes a difference.

 

[mikecr]

@mikecr When you refer to "optimum pin setting" are saying that you adjusted firing pin fall?
If so, what measurement did you settle on for that particular rifle?

By adjusting the lock down point on my firing pin (in the cocking piece), I'm setting potential pin fall from sear release. I'm seeing the adjustment easiest from the bolt face. Actual pin fall would be measured from the shroud end.

On that gun, released pin protrudes .024" from bolt face, and it looks like pin fall is ~.240"
This turned out to be optimum for Fed205, and this gun's trigger, pin, and spring.
It can also be adjusted with trigger hangers.

I guess now all I need to do is measure & define energy attributes of that striking system, and then I'd know that much anyway.. Likely more than just force per area, and including rate of speed.
I have crushed a primer flat in a vise, just for the learning, without setting it off. And I've deprimed many live primers without ever setting them off. So it's not just energy, but a certain type of energy.

And how grouping opens, closes, opens, with all primers igniting, just by changing striking energy?
I have no idea

 

[Doom]

Most of us have carefully removed a live primer from a case. Taking this a bit farther, if one wanted he could measure the thickness of a primer, seat it, carefully remove it and then remeasure its thickness in order to better understand what had been done. I actually called CCI and asked a technician about what they recommended. He told me that the primer should be compressed until the bottom of the anvil is flush with the cup. You might want to give that a try and then examine the primer held, top and bottom, between the jaws of a caliper, using a 20X loupe. You may be surprised.

I believe that the description from CCI is what is shown in Uncle ED's diagram. Was that your interpretation?

 

[ronemus]

Nice images. Looks like your limited to the cup edge touches the case. You cannot push it any deeper because you cannot crush/compress the cup itself. I am getting tired of all the primer talk. Do we need 100's of post every year explaining the same thing.

The cup is brass with a rounded edge between the face and side - that edge can be deformed with moderate pressure after the cup bottoms in the primer pocket; however, I have no way of knowing whether the "touch" I feel is the cup bottoming or the anvil first touching the bottom of the primer pocket. I do know that a primer seated with crush has a the round edge reduced and a larger diameter flat face.

I'm curious about what I'm feeling a "bottoming" and what "crush" is actually deforming. A cartridge with an observation slot cut into the primer pocket would allow finding some answers, but I no longer have access to a machine shop so it would be difficult to do.

 

[jelenko]

When I seat primers, I can feel an initial resistance, a little more movement, then pretty hard stop.
I have found that after the hard stop, I can getting the top of the primer seated deeper a little by really squeezing. As you mentioned, after squeezing really hard, the primer does look flatter.

Which is interesting. I'm not excited about the idea of 'deforming' the cup itself => gonna try stopping at the hard stop.

 

[mikecr]

Not supposed to be smashing the cup into pockets.
Just anvil leg touch plus a crush/sensitize value

If you don't go far enough then pin strike will finish the job, subtracting striking energy to do this by varying amounts of pocket fit.
If you go too far then you can affect integrity of primer chemistry, and get inconsistent ignition.
All primers will go bang though,, they're reliable for that much.

 

[BoydAllen]

By adjusting the lock down point on my firing pin (in the cocking piece), I'm setting potential pin fall from sear release. I'm seeing the adjustment easiest from the bolt face. Actual pin fall would be measured from the shroud end.

On that gun, released pin protrudes .024" from bolt face, and it looks like pin fall is ~.240"
This turned out to be optimum for Fed205, and this gun's trigger, pin, and spring.
It can also be adjusted with trigger hangers.

I guess now all I need to do is measure & define energy attributes of that striking system, and then I'd know that much anyway.. Likely more than just force per area, and including rate of speed.
I have crushed a primer flat in a vise, just for the learning, without setting it off. And I've deprimed many live primers without ever setting them off. So it's not just energy, but a certain type of energy.

And how grouping opens, closes, opens, with all primers igniting, just by changing striking energy?
I have no idea

If your pin only protrudes .025 from the bolt face, it is way out of spec. While you can get away with less, the usual specification is .055. The primer itself is supposed to stop the pin when actually firing a cartridge, not the front of the pin flange, which is what is supposed to stop it when doing empty chamber dry firing. A figure that I have heard for protrusion during firing is slightly longer than what you have on a decocked bolt, so you may have an undesirable condition with softer primers or cartridges that have a little more than the optimal amount of shoulder to head clearance.

 

[BoydAllen]

Nice images. Looks like your limited to the cup edge touches the case. You cannot push it any deeper because you cannot crush/compress the cup itself. I am getting tired of all the primer talk. Do we need 100's of post every year explaining the same thing.

The nice part about having titles on threads is that you can do some sorting before reading. If a subject is of no interest then you can simply leave it to others.

 

[JEFFPPC]

So after all the blathering on various often repeated subjects....He who reads the conditions correctly and then executes no mistake shots, wins. Don't get lost in the weeds. Yep, why would you use the Search function to learn about a subject, I get it Webster.

 

[K22]

If you do what I suggested in my earlier post, you will probably discover that try as you might, with a hand tool, you may not be seating them quite to where CCI recommended. I am not saying that I know of any problems from not hitting that mark, just that based on my experience I do not believe that anyone using a hand tool is harming the primer or its performance no matter how hard they squeeze, but of course most would rather discuss without doing any real measuring.

As always, Mr. Allen makes an excellent point. On this specific issue, I don't have any reason to test that I can detect. However, I had some significant performance problems a couple of years ago when I had to change cleaning solvents.

I was totally puzzled because I was doing everything "right" according to all the expert opinions I had read. However, I began testing some non-conventional assertions. I hate testing but disciplined myself to conduct a controlled test to test the assertions to see if it solved my problem. I was able to solve my problem.

So, Boyd makes an excellent point, there is no substitute, at least in my opinion, in verify assertions by range testing. I've done this a few times in my shooting life and it works because performance results don't lie.

PS: I only embark on testing when I have a performance problem because I hate bench shooting and testing. I'd rather be hunting or doing practical shooting practice to test my varmint field marksmanship skills. 

 

[mikecr]

If your pin only protrudes .025 from the bolt face, it is way out of spec. While you can get away with less, the usual specification is .055.

Boyd I don't know where a .055" protrusion standard comes from.
Is there a source for these kind of standards. Like xx spring force, yy pin weight, zz pin travel, aa pin diameter? If you can think of it, I would sincerely like to review this.

What I do know is that .055 of released pin protrusion is dead wrong for my Cooper M21.
Tested best IS .025 (I tested it on targets), and this is plenty of normal primer indention.
Other qualifiers: My headspace is always 1-1.5thou,, my pockets are set to standard depth with the Sinclair uniformer,, primer crush with Feds is always set to exactly 2thou.
I did not imply that my setting applies to anybody else. It's just my best, which is meaningless until defined and validated across at least several completely different challenges.

Here, there is no contact with a pin flange, especially with only .025" protrusion, even with dry firing.
This in particular just happens to be one of the first things I typically have to fix with bolts, with every action, including BATs -to ensure no impediment or energy lost with pin travel. I would never accept it, as it would source a really ugly vibration.

The cocking piece is set to allow clearance with the shroud, and my bolt turn is indexed to a stop, so that on dry firing, my bolt handle does not move or turn at all. There is no click or clanks with bolt handles jumping about on my guns.
If you haven't, then check this with your guns. Close the bolt handle and dry fire. Does your bolt handle move? Did it turn a bit open or close? If it does then no doubt the dry firing was noisy with some striking force converted to undesirable vibrations. Some of this may very well be in play, when striking primers.
And you can do that as well, while watching that bolt handle.

A point of my earlier reply was that I tested this, and found gain in it.
I didn't ask anybody what they thought it should be, I tested for my self to find out, and did find out.
I'm sure most folks don't even think about it, and I'm hoping to get them thinking about it.
Maybe they could find gains, and share what they learned.

 

[INTJ]

I have posted repeatedly about how I optimized priming cases. It started with reading (a few years ago) what @mikecr said about the K&M Primer Gauge, which is still (I think) the only tool that allows you to seat each primer in each case to an exact crush amount.

I tested this is 6BRA 1K BR light gun and found a 5 consistent FPS reduction in ES vs seating primers to a consistent depth below the base of the case. I theory, this widens my tuning node a bit. I have not tested in my 300 SAUM IMP heavy gun, as it has double the case capacity.

I seat all my LR BR loads with the K&M Primer Gauge, after uniforming pockets and weighing primers.

 

[BoydAllen]

Boyd I don't know where a .055" protrusion standard comes from.
Is there a source for these kind of standards. Like xx spring force, yy pin weight, zz pin travel, aa pin diameter? If you can think of it, I would sincerely like to review this.

What I do know is that .055 of released pin protrusion is dead wrong for my Cooper M21.
Tested best IS .025 (I tested it on targets), and this is plenty of normal primer indention.
Other qualifiers: My headspace is always 1-1.5thou,, my pockets are set to standard depth with the Sinclair uniformer,, primer crush with Feds is always set to exactly 2thou.
I did not imply that my setting applies to anybody else. It's just my best, which is meaningless until defined and validated across at least several completely different challenges.

Here, there is no contact with a pin flange, especially with only .025" protrusion, even with dry firing.
This in particular just happens to be one of the first things I typically have to fix with bolts, with every action, including BATs -to ensure no impediment or energy lost with pin travel. I would never accept it, as it would source a really ugly vibration.

The cocking piece is set to allow clearance with the shroud, and my bolt turn is indexed to a stop, so that on dry firing, my bolt handle does not move or turn at all. There is no click or clanks with bolt handles jumping about on my guns.
If you haven't, then check this with your guns. Close the bolt handle and dry fire. Does your bolt handle move? Did it turn a bit open or close? If it does then no doubt the dry firing was noisy with some striking force converted to undesirable vibrations. Some of this may very well be in play, when striking primers.
And you can do that as well, while watching that bolt handle.

A point of my earlier reply was that I tested this, and found gain in it.
I didn't ask anybody what they thought it should be, I tested for my self to find out, and did find out.
I'm sure most folks don't even think about it, and I'm hoping to get them thinking about it.
Maybe they could find gains, and share what they learned.

Rather than answer you immediately, I am going to undertake some research specific to your rifle, by contacting the manufacturer. As far as the standard for protrusion, I suggest that you google it, or simply click on this link.

Google Search

The information has been so widely published for so long that for me it falls into the category of common knowledge.

 

[CT10ring]

I use a Sinclair hand priming tool which gives me an excellent feel in seating primers. I seat slightly below flush and or to the bottom of the primer pocket, but I've never had to apply excessive pressure to achieve this level of seating.

Is this making too much of something that isn't that complicated?

Ditto. Sinclair hand priming tool gives a great feel. Also, there are shims included to dial in the proper depth.

 

[Bronsin]

I have posted repeatedly about how I optimized priming cases. It started with reading (a few years ago) what @mikecr said about the K&M Primer Gauge, which is still (I think) the only tool that allows you to seat each primer in each case to an exact crush amount.

I tested this is 6BRA 1K BR light gun and found a 5 consistent FPS reduction in ES vs seating primers to a consistent depth below the base of the case. I theory, this widens my tuning node a bit. I have not tested in my 300 SAUM IMP heavy gun, as it has double the case capacity.

I seat all my LR BR loads with the K&M Primer Gauge, after uniforming pockets and weighing primers.

I'm going to make a long story short. I don't trust this tool right now. My tool doesn't seat primers to the depth that the indicator says that it does. I can consistently feel it bottom out .004-.005 farther in than the setting says it needs to be. I got suspicious that it was even seating primers to the bottom, so I tried my Sinclair tool and it easily drove them in deeper.

It seems there's a spring between the plunger and the carrier that holds the indicator, and it just compresses that spring instead of pushing the primer in farther. Going to take it to work tomorrow and pull it apart, then make a spacer where this spring goes and try it again.

Edit: I took it apart here and found the spring. Will make a solid replacement for it and see how it goes.

 

[BoydAllen]

I believe that the description from CCI is what is shown in Uncle ED's diagram. Was that your interpretation?

Yes.

 

[INTJ]

I'm going to make a long story short. I don't trust this tool right now. My tool doesn't seat primers to the depth that the indicator says that it does. I can consistently feel it bottom out .004-.005 farther in than the setting says it needs to be. I got suspicious that it was even seating primers to the bottom, so I tried my Sinclair tool and it easily drove them in deeper.

It seems there's a spring between the plunger and the carrier that holds the indicator, and it just compresses that spring instead of pushing the primer in farther. Going to take it to work tomorrow and pull it apart, then make a spacer where this spring goes and try it again.

Edit: I took it apart here and found the spring. Will make a solid replacement for it and see how it goes.

Mine doesn't do that. It is very solid--no springiness at all when seating. I would double check to make sure it's assembled correctly before modifying the tool. There is a learning curve to using it.

The problem with using only feel is that it's very hard to tell the difference between a tight pocket and the primer bottoming out.