Primer seating depth

[Tuxedo007]

Seat by feel. Not measured depth. Setting them below flus is just a given for safety.
The anviles feet must be bottomed out. If they are not then your SDs go up. Been proven over and over again in be chrest.

I've been seating by feel for more years than I want to admit to! When I started handloading back in the "dark ages" the 1st thing I was told was to make sure the anvils of the primers were bottomed out it the primer pocket!! I've never had a problem, unless I had a brain fart and didn't pay attention to what I was doing! Good shooting & be safe! Tuxedo007

 

[T-shooter]

Seat by feel. Not measured depth. Setting them below flus is just a given for safety.
The anviles feet must be bottomed out. If they are not then your SDs go up. Been proven over and over again in be chrest.

Sounds reasonable. I may have to change how I seat primers. Any recommendations on a hand seating tool? I do uniform the primer pockets but there are many that are a little deeper where the cutter doesn't touch.

 

[swadiver]

I just got this and like it lot. replaced my RCBS tool.

https://www.midwayusa.com/product/5...latinum-series-perfect-seat-hand-priming-tool

 

[jepp2]

When I prepare my brass I uniform all my primer pockets. Doing so, you see how far from the proper geometry many are. Unless you are uniforming your primer pockets, I don't see how you "pick" an exact number for how far below flush the primers need to be seated.

Once you get rid of the radius that exists at the edge of the bottom of primer pocket by cutting it to a uniform depth all the way across, now you can get a basis for how far below flush is the correct amount for the primers you are seating. Of course that number will depend on how deep you are cutting the pocket, and what primers you are using.

 

[Grimstod]

Sounds reasonable. I may have to change how I seat primers. Any recommendations on a hand seating tool? I do uniform the primer pockets but there are many that are a little deeper where the cutter doesn't touch.

You have to find one with good feel. That means very little leverage. The lee one is good. Here is a good article on how to feel the bottomed out primer.
http://www.premieraccuracy.com/bulletin pages/bulletin-post-lee-auto-prime-class.html

 

[cw308]

I uniform all my primer pockets , I seat the primers with a RCBS Ram priming unit . Once I feel the primer seat the lock ring is set an that's it. Never had a problem with primers. I use bench rest primers for rifle , CCI & Federal , both fire the same no difference in group size.

 

[Ron Blain]

For the mathematically inclined FIRING PIN IMPACT STUDIES is a good read on the subject of primers and firing pins, a little dry but a good read. I hand prime and have always hand primed simply because I feel I get a better "feel" for what my primers are doing, I also always seat until I feel the primer bottom out in the primer pocket. There is no shortage of tools available for primer seating and like the mouse trap there is always going to be a new and improved tool.

My reasoning for seating a primer till it bottoms out is pretty simple in that if we look at brand new out of the box factory manufactured primers we can see how the anvil extends just above the rim of the primer cup. Under magnification I see this on all new primers.

Notice the anvil does extend beyond the top rim of the cup. Primer cups on cartridges have depth and width specifications and primers have height and width specifications. Depending on the actual numbers my primers when seated till they bottom out generally end up about 0.003" below the case head. Pictured below using a white business card as a straight edge.

This works for me and had worked for me for over 40 years. If I really thought a newer fancy mouse trap would work better I would get one but at this point I'll continue with my existion mouse traps.

Ron

 

[BillPa]

I just got this and like it lot. replaced my RCBS tool.

https://www.midwayusa.com/product/5...latinum-series-perfect-seat-hand-priming-tool

I've been playing with one the last two or so months with two mods. One, made it a bit more used friendly by replacing it's 59 Cadillac coil spring with a lighter one and two, made a .020" shim to slip in between the handle and body to limit it's ram down stroke so it can be used it to seat primers one at a time without the primers taking flight out the tray slot. If for some reason I want to or need to use the tray I'll simply remove the shim.
On the downside it may be a little on the bulky side for those with smaller meat hooks, but overall its not a bad piece considering the price.
Bill

 

[Medic505]

Yes, but I don't have a depth micrometer.

You reload and you don't own vernier calipers?

 

[Richard Coody]

Look at the tail end of your caliper, it should/might have a small extension that moves in or out depending on opening or closing caliper jaws. This may be used to determine depths, probably up to .25 in a hole of same diameter. Should you not have a caliper look for this feature upon selecting a caliper. I use this feature frequently.

i don't really care how deep my primers are.seated just as long as they are below flush and firmly seated into the bottom of the pocket.

i use only lapua brass and don't mess with the primer pockets or flash holes. primer pockets on lapua brass are often tight. first few firings take considerable effort to get primers seated properly. but i find not messing with them makes the brass last longer without getting loose primer pockets.

 

[centershot]

I have one particular brand and caliber of large rifle brass that will not seat below the surface of the brass. I used a Sinclair primer pocket tool to uniform the pockets. It will not cut any brass from the middle of the primer pocket, only the circumference. My Lee hand tool (old) will not seat below the brass head. The primers are bottoming out, I can feel it. How do I solve the problem? Buy another brand of primer pocket tool or get a bench mounted primer tool? This is the same for all brands of primers. Bad lot of brass?

 

[retired]

it cuts brass where it touched the brass.
in a primer pocket this is generally at the edge and works in.
the edge/corner because the radius on the tool and the pocket are different.
did you use the tool till it quit cutting brass ?
take your caliper and measure the primers. there is a primer spec in SAAMI, go look,
are the primers out of spec ?
are you using the correct tool ? large pistol is not the same as large rifle.

I have one particular brand and caliber of large rifle brass that will not seat below the surface of the brass. I used a Sinclair primer pocket tool to uniform the pockets. It will not cut any brass from the middle of the primer pocket, only the circumference. My Lee hand tool (old) will not seat below the brass head. The primers are bottoming out, I can feel it. How do I solve the problem? Buy another brand of primer pocket tool or get a bench mounted primer tool? This is the same for all brands of primers. Bad lot of brass?

 

[ratbuster]

Here's an interesting article on primers that covers seating depth among other things....

http://www.targetshooter.co.uk/?p=1471

 

[retired]

here is what it says
"This requires a seating tool with enough ‘operator feel’ to know when the primer has bottomed in the case-pocket and to then add a teensy-weensy amount of ‘crush’."

Here's an interesting article on primers that covers seating depth among other things....

http://www.targetshooter.co.uk/?p=1471

 

[danny]

I have one particular brand and caliber of large rifle brass that will not seat below the surface of the brass. I used a Sinclair primer pocket tool to uniform the pockets. It will not cut any brass from the middle of the primer pocket, only the circumference. My Lee hand tool (old) will not seat below the brass head. The primers are bottoming out, I can feel it. How do I solve the problem? Buy another brand of primer pocket tool or get a bench mounted primer tool? This is the same for all brands of primers. Bad lot of brass?

centershot,
It is possible, though a remote one, that your primer pocket uniformer is too short. I had one many years ago, and in my inexperience, I was crushing the primers in to get them below flush. I slammed off 5-7 rounds from my AR until I figured it out. Check the length of your uniformer against some specifications for the height of the primer in use and depth of the pocket required. I called I called Sinclair back then. They had me return the tool. I got a brand new one right away. After that, the primer pockets checked as in spec. and seating went perfectly.

Danny

 

[jepp2]

Check the length of your uniformer against some specifications

This is your specifications

 

[Bob L.]

here is what it says
"This requires a seating tool with enough ‘operator feel’ to know when the primer has bottomed in the case-pocket and to then add a teensy-weensy amount of ‘crush’."

I tried one teensy-weensy and found it wasn't enough. I now add two teensy-weensies.

 

[danny]

This is your specifications

View attachment 1044737

Thanks jepp2.

Someone will benefit from this.

Danny

 

[ClassCat]

The primer needs to be flush with the case head. Not sticking out, not recessed. It's that simple.

Dang !!! I been doing it wrong for 25 years

 

[onelastshot]

I spent the money a got a good hand held Sinclaire primer seater. My primers are set by feel; every cartridge is different and every piece of brass varies by learning what a primer feels like when it is sufficiently seated is a learning process. I don't have misfires or seating problems. There's a simple learning curve where you develop a feel where you know you have a proper depth.