Seating primers too deep???

[Maximumbob54]

I didn’t want to hijack someone else’s thread…

I have the latest generation RCBS hand primer and the bench mounted primer and suddenly I'm seating primers too deep on the both of them. I think with the bench mounted unit I may just be pushing down too hard but with the hand primer I've always just squeezed until the handle clicks against the body. I have always used the Lee shell holders that come with the Lee dies and this has never been the problem. Just to make sure it isn't the problem I bought a RCBS .38/.357 shell holder and still get the same problem. In retrospect the slot where you mount the shell holder over the two halves of the primer feed section force it to the top anyways. I usually use Tula primers so that was my second suspect in that maybe it's a bad lot of them. But how would you seat it deeper than the pushrod allows even if they were too short??? And to prove to myself that's not the problem I broke open some Winchester primers and they do the same thing so it's not the Tula's. But they are seating low enough that I’m getting light strikes on my ammo and that means wasted components.

Some pics to show the problem:



At first I thought it might be the mixed brass so I switched to brand new Starline brass and got the same thing.

The top two show unfired ammo with primers seated too deep.

The middle four show the two on the left used in a M&P R8 and the two on the right used in a Security Six.

The bottom two were shot in the Security Six as that one at least shoots about 80% of the ammo while I'm lucky if the M&P R8 ignites two out of eight in the cylinder. The answer for that one was NOT a C&S extended firing pin as that only gave me my very first pierced primer. That was exciting.

I know I'm using the small push rod that fits the two plastic halves as trying to drop the larger rod in is a no go as soon as it hits the plastic so the unit is put together correct. I took it apart for cleaning thinking something may be caked on or gummed up but nothing looked dirty and this isn't a tool that really gets dirty anyways.

The heck am I doing wrong all of a sudden???

 

[kwselke]

I'm just an old armature hand loader, but I do not see in the picture that the primers are seated too deep. If that were the case you should be able to note crushing on the surface of an unfired primer.

My thoughts would be the primers pockets are too deep, the primers themselves are out of spec and too short, or you've got firing pin issues. Having light strikes from two different handguns is perplexing.

I have actually applied to much pressure after primers bottomed and there is a definite mark left on the primer face. I'd ask for a 3D image, but I only have a 2D monitor.

Have you recently switched brands or lots of the primers you been using.

 

[SMSgt]

I don't see how it's physically possible for a hand primer to suddenly start seating deeper. If anything, as the hand primer components wear, the primers should seat shallower (my old Lee did just that as the lollypop wore down). The seating rod should push the primer in until it bottoms out; any further and it would begin to crush the primer or leave marks on the face.

Either your primer pockets are too deep (Take some measurements) or the primers are out of spec (Odd that two brands would be, but measure anyhow).

 

[BlueOvalBandit]

My 625 runs 5-5.5lbs in DA which means I need to seat Federal primers with AUTHORITY in mixed brass to avoid light strikes.

I have yet to over seat a primer, and I crush them to the point you can see a small dent from the anvil poking up. It should be impossible to overseat with correct primer pockets as you should be bottoming them out in the first place. Those pic do look deep but its hard to tell. Put a straight edge over the bases for a better view of primer depth.

 

[Maximumbob54]

I think I still have those cases setting out so I will try for another pic tonight. I can't see how the primer pockets would be too deep as the primer should only seat as far as the ram can push it and it only lifts so much. I can ease them in and keep checking to see they haven't gone to far but I've never had to do that before.

 

[Rule3]

From the other thread:

How does one seat a primer too deep?? Did you mess with the primer pockets? Too high I understand but not deep? My primers just seat and I do not even consider high or low any caliber.

You would have to be crushing the cup,anvil etc somehow.

Are you working out again and have the Thumbs of Steel video??

I have the Lee orginal round, The RCBS and also prime on the LCT press. All brands, Wolf, CCI, Win. About every caliber, never seated a primer too deep. So either your primer tool is messed up or you are squeezing the handle so hard it's deforming the primer. There is a section in the Lee manual about a guy breaking the handles off or something,

Sometimes I push so hard on the press primer I think it will go off and no problem.Like SB brass.

Only thing I can think of.

My R8 went back to SW twice for light primer strikes, One was crane adjustment the other the FP was replaced.

I would narrow it down first to one gun, one brand primer and one tool. You have too many variables going on.

First thing is check the mainspring tension screw!

 

[varmint243]

It has been my experience that light primer strikes come from not fully seating the primer.
The first firing pin hit seats the primer, the second firing pin hit fires the round.
Shooting PPC with "tuned" double action revolvers I became very familiar with this.
I now seat all primers by hand before running them thru the progressive press.
I have never seated a primer too deep.
It's easy to feel when they bottom just right using a hand primer.

 

[kwselke]

I bet you are seating the primer too high. The impact of the firing pin is partially absorbed fully seating the primer and there is not enough force left to ignite the primer once it has bottomed. If you are pushing the thumb lever until it clicks against the handle of the hand priming tool, take calipers and measure the priming rod you are using then call RCBS to make sure it is long enough to fully seat the primer.

 

[bigedp51]

The deepest requirement for primer seating I have ever seen was for the 7.62 Nato at .008 below the serface of the case.

Below is a diagram showing primer seating and primer crush.

What is your firing pin protrusion, you could have debris or a mechanical problem restricting firing pin travel.

 

[Maximumbob54]

I have searched across the bench and I must have already pulled everything and the brass is in the tumbler right now. I wish I had used the caliper to see how deep they were. I did at least salvage all the unused powder and the lead will be melted back down for fresh boolits. I didn't want to try and ease the primers out and reseat them so i just punched them out. I thought for sure I saved a few though but I guess not. The mind is a terrible thing to waste... No, I'm not the state champ of thumb wrestling, the tension screw is tight, and if you look at the light strikes above vs. the fired cases you can see they show far more primer pocket than the fired do.

At least some eye candy of the offending party:



No, the Hogue wood didn't stay as it just looks wrong on the gun. I'm thinking some VZ may be in order once they get out a round to square grip out.

Take a look at the pic as to why I'm not racing out to send her home...

 

[kwselke]

Did you try more than one hammer strike? My thinking is that if the first strike seated a high primer the second strike would make it fire.

 

[Boge]

I don't see how it's physically possible for a hand primer to suddenly start seating deeper...

Elmer Keith wrote of this years ago in that on used brass primer pockets flow in BOTH directions. I found this out the hard way years ago and in a most embarrassing manner. I had just bought a new Sinclair carbide primer pocket uniformer and used it on some heavily used brass. During a match I got tons of light hits and felt like a fool. Now we know that it is impossible for the cutter to go beyond SAAMI specs. I measured some using a depth mike and sure enough the primer pockets were deeper on some cases!!

Moral of the story: uniform the primer pockets ONCE when new and never again. I think it was a combination of primer pocket flow, rim thickness variation, headspace & FP protrusion. There are stacking tolerances involved here.

 

[rwsmith]

The Lee Autoprime

The hand tool that I use is the old Lee Autoprime and you can feel the primer bottom out when the handle is 1/2" to 3/4" from the body. There's no positive stop.

It does sound like the primer pockets are too deep.

 

[Maximumbob54]

Did you try more than one hammer strike? My thinking is that if the first strike seated a high primer the second strike would make it fire.

You can run a finger tip across them before they ever see they chamber and feel I ran them too deep so it's not that they are seated too high. The rare time I have done that I can feel the primer hang up on the shell holder.

 

[jackpearl]

Look at the pics--- it looks like the top (unfired) primers aren't seated as deep as the ones that wouldn't fire ( middle ones ) All of the middle ones look to me, as stated above, were pushed in even further with the strike of the firing pin. It seems the pockets are too deep---for whatever reason.

 

[kwselke]

You can run a finger tip across them before they ever see they chamber and feel I ran them too deep so it's not that they are seated too high. The rare time I have done that I can feel the primer hang up on the shell holder.

I take that to mean you did not try a second hammer strike?

Here are the issues.

If you are seating the primer too deep it would show signs of crushing, and if you are using a thumb powered tool you would be worried about setting off the primer with the force you were applying.

The primer pocket may for some reason be too deep.

The primers may be too short.

The tool you are using to seat the primers may not be in proper adjustment, and you think the primer has bottomed and your primer still is not seated.

The last variable would be a light firing pin strike from the firearm.

Considering the comments that have been made from folks with experiences with light strikes due to high primers, you need to decide what your issue is.

Good luck and good shooting!

 

[forestswin]

Do you have flat end of primer rod up? Or rounded end up?
Rounded end should be down.

 

[Nemo288]

"Moral of the story: uniform the primer pockets ONCE when new and never again."

This is a good example of why I like this forum and read as much as I can.

I am involved in a project that includes this very subject. I am reaming
the large pistol pockets of a box each of 445 Gates and 445 Starline brass to accept rifle primers.
I will then compare these to the ones primed with large magnum pistol primers.

Due to your advice I will leave the old (converted) 30USA cases alone.
They could theoretically be 100 years old.

Thanks again for the story.

---
Nemo

 

[Maximumbob54]

Look at the pics--- it looks like the top (unfired) primers aren't seated as deep as the ones that wouldn't fire ( middle ones ) All of the middle ones look to me, as stated above, were pushed in even further with the strike of the firing pin. It seems the pockets are too deep---for whatever reason.

I had a thought at of all times during my hour commute to work this morning. I'm going to seat a primer the same way I have been and then turn around and punch it out and see what it looks like. For all I know I'm crushing them inside and don't see it on the outside.

I take that to mean you did not try a second hammer strike?

Some of them yes until I realized the 327 wasn't shooting them. Then some of them ignited in the Securuty Six. Maybe about a little over half of them.

Here are the issues.

If you are seating the primer too deep it would show signs of crushing, and if you are using a thumb powered tool you would be worried about setting off the primer with the force you were applying.

The primer pocket may for some reason be too deep.

I don't think so but could be. Starline makes some pretty top of the line brass.

The primers may be too short.

This would have to be true of both the Tula and Winchester primers as I have tried both.

The tool you are using to seat the primers may not be in proper adjustment, and you think the primer has bottomed and your primer still is not seated.

The problem is very much they seat too deep. I am more and more thinking I'm crush fitting them.

The last variable would be a light firing pin strike from the firearm.

I think it is more due to the firing pin not being long enough to impact the primer with enough force but I could be wrong.

Considering the comments that have been made from folks with experiences with light strikes due to high primers, you need to decide what your issue is.

Again, I will test one and push it out to see and take a photo of my error if I see anything.

Good luck and good shooting!

Answered in bold in the above quote.

Do you have flat end of primer rod up? Or rounded end up?
Rounded end should be down.

The flat end is up. I've missed that before and it leaves an obvious mark if the round end is up.

 

[Waywatcher]

I've had misfires from too-deep-seated primers before; twice if my memory serves. I got out the calipers and it was about 0.013" deep, and was easily felt as "way too deep." They wouldn't ignite even with 5 strikes.

Then I went too far the other direction because I was worried about seating too deep, and didn't push my primers deep enough and had two misfires from high primers. I knew they were high because they ignited with a second strike.

Primer seating is a delicate task that requires a firm yet gentle touch to "keep it between the ditches." Not too deep, and not too shallow.