Will a primer .004 off the bottom of the pockets have different burn characters?

[GSSP]

I ran a primer test a few weeks ago with CCI 250, Fed215M, Rem 9-1/2 and WLRM primers. CCI 250 and WLRM age the best results with accuracy and small SD but the highest ignition failure rate. I really want to use the WLRM primers.

After much thought, fiddling, measuring and testing I found out an answer to my question. Now, it begs another question.

New or 1x fired 338 Edge (Nosler 300 RUM brass necked up) brass.
Primer pockets reamed with Sinclair 8000 Uniforming tool which ended up reaming pockets .134" deep and SAAMI max depth is .132" which resulted in numerous misfires because the firing pin had too much real estate to travel to get the primer to bottom out and provide enough resistance so the primer would fire. This when I use my Sinclair priming tool which gets the primers flush, the primers have as much as .012" of travel before they bottom out.

Discovered if I used my press mounted Forster Coax press priming device, I can get the primers .006" below flush and the primers fire.

Here is my question.

If the primer is approx .004" away from the flash hole do you think it might negate the results of the first test I did vs having the primers flush against the bottom of the pocket? Do you think I should repeat the test; .004" off the bottom vs pressed down against the bottom?

Thanks,

Alan

 

[bigedp51]

Primers are to be seated with a slight primer crush or preload, if the anvil is not touching the bottom of the primer pocket the firing pin blow is reduced as the firing pin finishes seating the primer.

From the Nosler manual below.

As primers are seated to the proper depth, the anvil is pressed slightly deeper into the cup, lightly compressing the primer pellet. This sensitizes or arms the primer so that it will be ignited by the blow of the firing pin. However, primers that are seated too deep are hazardous as the anvil may be pressed into the priming pellet too far making the primer dangerously sensitive. Ideally, primers should be seated approximately .005” below flush with the case head. At this depth, they are sufficiently deep to be safe and sensitized, but are not so deep as to be out of reach of the firing pin.

 

[2506]

If your primer is not seated to the bottom of the primer cup you WILL have misfires. The anvil has to be supported by the bottom of the pocket to allow the compression of the priming compound pellet between the cup and anvil when the cup is struck by the firing pin to ignite. If the primer is not seated to the bottom the firing pin has to knock the primer to the bottom before the primer will fire. When people first started using Wolf primers they complained that the primers were no good because they had misfires sometimes. The problem was that this primers was just a bit larger and had a harder primer cup and people were not getting them seated to the bottom of the primer pocket. I was one of these. Once I found that I had to really put some force into seating them the misfires went away.

 

[Walt Krafft]

I have seated thousands with a RCBS hand primer with no problems.

 

[antunRC]

Wow, you just woke up an 11-year-old thread!

 

[Webster]

Primers are to be seated with a slight primer crush or preload, if the anvil is not touching the bottom of the primer pocket the firing pin blow is reduced as the firing pin finishes seating the primer.

From the Nosler manual below.

As primers are seated to the proper depth, the anvil is pressed slightly deeper into the cup, lightly compressing the primer pellet. This sensitizes or arms the primer so that it will be ignited by the blow of the firing pin. However, primers that are seated too deep are hazardous as the anvil may be pressed into the priming pellet too far making the primer dangerously sensitive. Ideally, primers should be seated approximately .005†below flush with the case head. At this depth, they are sufficiently deep to be safe and sensitized, but are not so deep as to be out of reach of the firing pin.

Don't understand a primer being too sensitive and dangerous. What do they mean be dangerous. They are not going to go off without a FP strike. I have been seating by feel to the bottom of the pocket for 55 years without a problem. I think you can find other expert opinions that state seat to the bottom of the pocket. The only misfires I ever had was when I tried adjusting my priming tool to vary the depth of seating.

 

[TTE]

 

[BoydAllen]

I have had a Sinclair priming tool since they first came out. since then, the newest version has some small differences, BUT the adjustment of the protrusion of the priming punch is still the same. The point is that it can easily be adjusted. Here is link to a PDF of the instructions.

https://www.varidecicognani.it/upload/armeriacicognani/files/SINCLAIR/PRIMING-TOOL-01.pdf

There are a large number of very fine competition shooters who seat primers by feel. You set the tool up so that the handle does not touch the body of the tool when the primer is seated as deeply as it can be with one hand, so that the gap is such that it is most comfortable to use. Insert the primer. The Sinclair tool requires that the operator loosen the head to remove a case, and then tighten it after one is inserted so that the head of the case is held firmly in contact with the part of the tool that the seating punch rises out of. This feature is unique and makes the seating depth independent of rim thickness. I do not recommend agonizing about when the primer is bottomed, simply insert the primer, then the case, rotate the tool head clockwise until it stops, and give the handle a firm squeeze. Doing this will bottom the primer and compress the pellet slightly, which is exactly what is needed. The idea of too much compression making a primer dangerous does not comport with may experience. Decades back, when I was a stout lad, doing manual labor, and had excellent hand strength, I had a tendency, since corrected of over doing my primer seating pressure, such that I actually deformed the shell holder retaining lips of a RCBS hand priming tool, Other than the damage that I did to the tool, there were no negative consequences. I say all of this fully realizing that there are a lot of OC reloaders who simply cannot deal with the idea that priming is this simple, and does not involve any measurement at all.

 

[Walt Krafft]

Wow, you just woke up an 11-year-old thread!

Wow!! Bed time was calling.

 

[Bronsin]

If you seat primers .004 from touching the bottom of the pocket, then you are actually seating them with the firing pin.

Geezuz. Zombie Thread

 

[Mark611]

I seat my primers in my bolt guns 4k deep from the top and my auto loaders 4 to 6k, I don't know far they are from being seated at the bottom of the pocket, I've never measured them, I have never had a problem, my accuracy is as good as I can shoot, I just did some load testing about 3weeks ago my 308win build 1/4 in groups at 100m 1/4 MOA @200m

 

[FDCaptain]

So, how did he measure the .004 from the flash hole?

 

[jds holler]

However, primers that are seated too deep are hazardous as the anvil may be pressed into the priming pellet too far making the primer dangerously sensitive.

Please excuse me if I display a slight involuntary eye roll right now. jd

 

[dellet]

However, primers that are seated too deep are hazardous as the anvil may be pressed into the priming pellet too far making the primer dangerously sensitive.

Please excuse me if I display a slight involuntary eye roll right now. jd

Poorly worded, but true.
The idea behind military primers, specifically for semi auto, #34 & #41 is to increase distance between cup and anvil to reduce possibility of slam fires.
Seating too deep, too much crush, increases that possibility on anything with floating firing pin. Slam fire as well as negligence in the case of a dropped firearm going off.

 

[searcher]

Based on the above posts, I think there should be a distinction made as to seating a primer "too deep" and actually crushing the primer. Big difference. Deepening the pockets always comes with increased chance of misfires if one goes just a bit too deep for the brand (or lot) of cases. Seating them flush to the top and then having the primer absorb firing pin energy while it pushes the primer that .004" before bottoming out may actually be worse than getting the occasional misfire (seated at bottom) as the amount of force absorption of the firing pin onto the primer will not likely be the same from shot to shot when the primer finally bottoms out after the strike, whereas the same amount of firing pin force on seated primers should be more equal - even if insufficient. Best to just replace the brass. I also agree with the posts made about the Wolff (and Tula) primers having had a bad rap as being bad primers. If they are poorly seated, one gets poor performance. Pretty much like every other aspect of loading. Do a poor job - and things don't usually work out too well.

 

[Webster]

I ran a primer test a few weeks ago with CCI 250, Fed215M, Rem 9-1/2 and WLRM primers. CCI 250 and WLRM age the best results with accuracy and small SD but the highest ignition failure rate. I really want to use the WLRM primers.

After much thought, fiddling, measuring and testing I found out an answer to my question. Now, it begs another question.

New or 1x fired 338 Edge (Nosler 300 RUM brass necked up) brass.
Primer pockets reamed with Sinclair 8000 Uniforming tool which ended up reaming pockets .134" deep and SAAMI max depth is .132" which resulted in numerous misfires because the firing pin had too much real estate to travel to get the primer to bottom out and provide enough resistance so the primer would fire. This when I use my Sinclair priming tool which gets the primers flush, the primers have as much as .012" of travel before they bottom out.

Discovered if I used my press mounted Forster Coax press priming device, I can get the primers .006" below flush and the primers fire.

Here is my question.

If the primer is approx .004" away from the flash hole do you think it might negate the results of the first test I did vs having the primers flush against the bottom of the pocket? Do you think I should repeat the test; .004" off the bottom vs pressed down against the bottom?

Thanks,

Alan

I don't believe primers burn, they detonate.