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Primer pocket uniformity?

Started by gman47564, January 02, 2022, 07:50:02 AM

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bikemutt

Good question Jerry, let me try to elaborate.

Imagine a flat washer with an OD the same as a primer pocket, and a center hole at least is wide as the flash hole.

If said shim washer happened to be 0.002 thick, and was set in the pocket, a pressed-in primer would be 0.002 off the flash hole.

It'd be a bit like herding cats but, who knows  :D   
Chris

Rob01

Lol that's one of the funniest things I have heard in a while but the funniest part is if you made it then there are people that would actually buy it! Lol

jvw2008

#17
Chris regardless of whether that idea would work or not, your post is an excellent example of thinking outside the box. ???????? Keep those ideas coming!

BCz

#18
Grant, as Rob01 stated I use a Lyman uniformer to clean my pockets, I'm finding it trims some pockets more than others. I feel that even though it may only touch the corners of some pockets it is giving me a uniform depth for the primer to bottom out on.
Keep in mind your brass blows out in all directions including the case head.

FWIW  It'll be a cold day in hell with lil devils wearing ice skates before I weigh primers.

jvw2008

????????

"FWIW  It'll be a cold day in hell with lil devils wearing ice skates before I weigh primers."

I made a similar statement several years back. I still feel the same way for most of my reloading. Right up until I'm trying to put together a 1000 yard sub 3" group.

mnbogboy

Quote from: HufD63 on January 02, 2022, 10:23:23 AMI've been weighing them over 2 years now. I'm looking for the low end and the high end not neccessarily the exact same weight. I had a round that sounded and felt weak and hit low on the forward pit berm not making the target out at DC a couple years ago. Had to be powder or primer and since I was weighing powder on the A & D I had to believe it was a primer.
DQ'd for the match after about $900 spent in travel and hotels alone. I haven't DQ'd from a weak round since LOL
In my dog saga I came upon an interesting result.
As it turned out my press priming bit me compared to hand priming. After studying my whole process the priming pin apparently was bent and it would force the primers in at an angle enough to tip the case to one side and jam the primer in the pocket. The cup would in turn distort to the point that the anvil would dislodge from the primer itself.
I pulled down all dogs and noticed loose anvils as i deprived those vases and caught the primer for reuse. Even all fired cases for some time had loose anvils upon depriming. The interesting part was the salt & pepper appearance of the salvaged powder from the dog cases. ( I had noticed this in the past.) Also had several ftfs with the bullet jammed in the lands! Several of this bullets had a definite carbon burn stain on their base. This told me the primer had indeed ignited and would account for the partially burned salt & pepper powder. The primers from those also clearly indicated a burn had taken place. The autopsies of all these ftfs give me some idea that primer strike indeed will affect every and all aspects of shooting. The anvil "vrush" on a flat bottomed pocket places it for proper operation. A poorly installed primer is a recipe for failure. Clean bottom pocket is the only way to fly.
Another problem encountered was it was super difficult to start the primers crooked in the pockets. For a time I actually chambered the pockets slightly to help start and seat any primer.
For a time I blamed my repurposing of "pull down" primers as the cause and climate control in my reloading room was trying the primers.
I guess we a learn from our mistakes.
11X Grandfather
Part time Savagesmith

mnbogboy

Quote from: HufD63 on January 02, 2022, 10:45:08 AMI've had only that one low power round and after weighing 6000+ primers over the last couple years I've not found one I was scared to shoot in a match. However like i said with the money invested in getting to a match from where I'm at im not going to leave it to chance.
There is no fun in weighing and measuring primers but to know i dont have an outlier in the box is worth it to me.
I weighed a couple of flats once and visually inspected the culls.
The priming compound when it dries in the cup has a tendency to crack the light [email protected] had some cracks. Evaporation during drying must be pulling the weight out. In this past years shortages I saved hundreds of cups and anvils. I could weigh some samples of each and determine if weight differences could be tied to the metal parts. Obviously the thinner cups may indeed be less apt to cause missed or delayed ignition.
11X Grandfather
Part time Savagesmith

mnbogboy

Quote from: mnbogboy on January 04, 2022, 06:38:29 PMI weighed a couple of flats once and visually inspe
Quote from: bikemutt on January 02, 2022, 06:50:12 PMGood question Jerry, let me try to elaborate.

Imagine a flat washer with an OD the same as a primer pocket, and a center hole at least is wide as the flash hole.

If said shim washer happened to be 0.002 thick, and was set in the pocket, a pressed-in primer would be 0.002 off the flash hole.

It'd be a bit like herding cats but, who knows  :D   
a paer punch may be just the tool to punch some out the righttype of paper or sheet plastic may just fit the material bill.cted the culls. Prepunched perforated material with oversize flash hole size holes might be a good start or a window screen type of material. The plastic stuff! Lol
The priming compound when it dries in the cup has a tendency to crack the light [email protected] had some cracks. Evaporation during drying must be pulling the weight out. In this past years shortages I saved hundreds of cups and anvils. I could weigh some samples of each and determine if weight differences could be tied to the metal parts. Obviously the thinner cups may indeed be less apt to cause missed or delayed ignition.
11X Grandfather
Part time Savagesmith

PaLuke

Eric Cortina has a video on YouTube about primer pocket uniforming tools. Apparently they believe with top quality brass anything except cleaning the pocket is a mistake. The brass is so uniform that measuring from the top of the rim to the bottom of the primer pocket is almost perfect in distance. This distance is the only measurement that matters. I never really thought about it. I just clean my pockets and shoot. Probably not the way to do it but with my luck I'd trash new brass. Take care.

BCz

Quote from: PaLuke on January 06, 2022, 05:57:37 AMEric Cortina has a video on YouTube about primer pocket uniforming tools. Apparently they believe with top quality brass anything except cleaning the pocket is a mistake. The brass is so uniform that measuring from the top of the rim to the bottom of the primer pocket is almost perfect in distance. This distance is the only measurement that matters. I never really thought about it. I just clean my pockets and shoot. Probably not the way to do it but with my luck I'd trash new brass. Take care.
I can tell you with absolute certainty that on new Lapua and Peterson I've had some pockets trim and some not.  This tells me the brass isn't perfect to begin with.
Our job is to get it as similar as possible, uniforming pockets is a absolute necessity in my book.
Let's look at pin fall and force...
If primers are set at various depths pin fall and striking force will vary causing a inconsistency in ignition and precision of rifles ability.
I wish I could upload pictures to show you how much variation there actually is to new and fired brass just by using a uniformer with a set depth.

gman47564

Let's look at pin fall and force...
If primers are set at various depths pin fall and striking force will vary causing a inconsistency in ignition and precision of rifles ability

This i don't understand.. by no means am i saying its not true.. i just dont understand how it has a effect on ignition.. does a primer burn hotter if its hit harder vs a lighter strike? In my mind the primer either ignites or it doesn't.. but there is probably more to it than that .. i just dont understand it.. can anyone shed light on how a difference in pin fall effects primer burn rate..
Grant

PaLuke

Hello, according to the video the pocket uniforming tool uses the bottom of the case as a stop for the depth of the tool. Out tools we use for installing primers use a shell holder and thus the top of the rim. I guess what he's saying in the video is that we can be changing the distance from the top of the rim to the bottom of the pocket with a uniforming tool which will add to inconsistency. I sometimes use my press primer installing tool and sometimes my Frankford Arsenal tool. Which pocket uniforming tool is best?  Thanks.   

HufD63

@gman47564

I don't pretend to completely understand it either Grant.

I do however believe ignition can be tuned and optimized. The farther a pin falls the less the strike force as the spring extends it should weaken. Probably difficult to measure yet testing by some of the top shooters from many disciplines show it matters.
A primer not fully seated that moves under the pin pressure is going to use up some of the pin fall energy. Again probably tough to measure.

I've had FTF rounds that when pulled down the priming compound was burnt and the powder was discolored but the bullet never left the case. I've had FTF rounds when fire forming from parent to improved cases that the headspace was a little loose and the whole round was moved forward and the primer was dimpled. This is clear proof if the primer or the whole case moves under the pin a weak strike will prevent ignition. Many times a second hit will light these off. Too much grease on the pin on a cold day will slow the pin enough to affect ignition as well.

So while I don't completely understand it ignition has to be just so to fire and with that I can believe irregularities in ignition will produce irregularities in accuracy. At that point it comes back to what is the acceptable amount of accuracy a shooter is looking for and is it being measured with a caliper or ruler?
Dave

BCz

Quote from: HufD63 on January 06, 2022, 09:01:56 AM@gman47564

I don't pretend to completely understand it either Grant.

I do however believe ignition can be tuned and optimized. The farther a pin falls the less the strike force as the spring extends it should weaken. Probably difficult to measure yet testing by some of the top shooters from many disciplines show it matters.
A primer not fully seated that moves under the pin pressure is going to use up some of the pin fall energy. Again probably tough to measure.

I've had FTF rounds that when pulled down the priming compound was burnt and the powder was discolored but the bullet never left the case. I've had FTF rounds when fire forming from parent to improved cases that the headspace was a little loose and the whole round was moved forward and the primer was dimpled. This is clear proof if the primer or the whole case moves under the pin a weak strike will prevent ignition. Many times a second hit will light these off. Too much grease on the pin on a cold day will slow the pin enough to affect ignition as well.

So while I don't completely understand it ignition has to be just so to fire and with that I can believe irregularities in ignition will produce irregularities in accuracy. At that point it comes back to what is the acceptable amount of accuracy a shooter is looking for and is it being measured with a caliper or ruler?
Thanks Dave!! Well put.

mnbogboy

Quote from: PaLuke on January 06, 2022, 05:57:37 AMEric Cortina has a video on YouTube about primer pocket uniforming tools. Apparently they believe with top quality brass anything except cleaning the pocket is a mistake. The brass is so uniform that measuring from the top of the rim to the bottom of the primer pocket is almost perfect in distance. This distance is the only measurement that matters. I never really thought about it. I just clean my pockets and shoot. Probably not the way to do it but with my luck I'd trash new brass. Take care.
I did have a complaint about starlings brass, supposed to be high quality but i noticed that pockets were deeper than other brands and my uniformer ( redding) never touched or cleaned the bottoms as other brass. I did notice this on another batch of brass after the fact. It could have been prime (norma) or Hornady in another caliber.
From.my experience initial informing with my cordless drill method takes the majority out of the pocket bottoms and subsequent firings stretch it out enough that the uniformed takes out a little more for the first two firings I also found that as the pockets stretch and loosen that more will show up at the bottom to be removed. My uniformed is the operation that removes primer residue from the pocket.
Also my routine of stabbing the pockets with an alcohol swab cleans up slight residue on the pocket walls an provides for a better primer seal. Dirty pocket walls lead to primer leakage and ultimately loosens the primers. The clean each cycle routine has given me better pocket fit and ultimately longer brass life with less scrap from loose pockets. The primer pocket go-no-go gauge is also a great tool for measuring primer pocket health. Loose fit primers can be pushed out by hand with a depriving pin.
I tried the pocket tightening method that uses a pin and ball bearing. It does work somewhat to snug up the head end (rim end) of a pocket.
11X Grandfather
Part time Savagesmith