Primer Pocket Prep

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Last Post 02 August 2024
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Wm Cook posted this 30 July 2024

I've been fighting issues with a worn-out hand primer that was seating the primer other than "in line" with the primer pocket. During that ordeal I took an interest in Primer pockets. One think led to another and I wound up buying a set from Midway/Burstfireguns that had a uniformer and a primer pocket reamer

With an electric drill the uniformer did not clean out the bottom of the pocket as I had expected, so I set up my drill press (Wilson case holder). It's a touch thing but I was able to balance the leverage on the mill to come away with a smooth clean square primer pocket bottom.

Depth of the pocket before milling was ~.130. Hard to measure.
Depth after milling was ~.133 / .134. at .132 it cleaned up about 60%. To square the base (clean milled base) it took more leverage. To clean it up I had to cut the pocket down to .132 to .135 (everything measured with a Mitutoyo caliper).
I'm using Federal 210 primers that look to hold around .128 in height. With the pocket depth of .134 plus the crush of the primer being seated, the primer is recessed below the case head .010 to .012. I fired a couple caps and the pin strike looks normal

- Should I be concerned about the primer being seated .010 to .015 below the case head? How much margin for error is there? Milling the pocket base will vary as will the amount of crush the primer is seated with, so I'm guessing there's a delta of .002 to .004 delta as the norm.

- When case prepping, what if anything do you do to the primer pockets?

- How concerned are you about getting a consistent crush against the bottom of the primer pockets.

I'm asking because in all the years of loading all I've ever done with primer pockets was to clean the pockets with a hand tool knowing that after cleaning there would be primer/powder residue remaining on 60-80% of the pocket base. When prepping brass for competition all I've ever done was weight (didn't help), turn the necks (tight neck so it had to be done) and de-bur the inside case flash hole (probably not necessary).

But if the primer is not seated flush against the pocket base in a consistent manner, with a consistent "crush" I would expect inconsistent ignition. Would you? Your thoughts would be appreciated. Thanks, BIll C.

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Tom Acheson posted this 30 July 2024

One of our BoD members (un-named) is a strong proponant of not even cleaning the primer pocket with the traditional brush. Lack of thorough testing and demonstrated proof that this task has merit, is a cited reason.

For some of us, stopping the practice is really difficult because it has become such a long practiced habit.

Look at all of the tools and gizmos that various manufacturers are more than willing to sell us. I too jumped down the rabbit hole of primer pocket reamers, uniformers and flash hole deburring tools, etc. Abandoning those practices and trying to to improve my bench technique has been my recent focus. Easy to say but hard to do.

For me my only primer related observation is the felt tightness of the pocket while seating the primer. Uniformity is the key interest. Eventually, after multiple firings a pocket can loosen up. Changing primer brand sometimes ameliorates that. But,,,,,what test based proof exits that a tight pocket vs, a loose pocket impacts accuracy? Obviously a primer that falls out of the pocket after being seated is cause for attention.

One of the tools in the attached photo looks the one I use to remove the primer pocket crimp that military ammunition uses. This is the only ammo I use with a jacketed bullet, for my M-1 Garand.

I'm sure others here will have a different view.

Tom

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Sevenfan posted this 30 July 2024

I use a K&M flash hole tool one time on new brass and never again. Uniform pockets, large and small, with Sinclair uniformers every time because it's part of my every time brass process. Does it matter, probably not, but it doesn't take much time to do and I don't mind doing it.

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Ross Smith posted this 30 July 2024

Bill: I uniform the pockets and clean the flash hole once. If the primers don't seat right I clean the pockets. Black powder fouling is harder to dig out than smokeless fouling! If you are a serious benchrest shooter then I think all the minutia adds up.

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Bud Hyett posted this 30 July 2024

Warren Page wrote in his book "The Accurate Rifle" that one season he cleaned pockets religiously and the next season he didn't. His average scores in each year were the same. He felt cleaning after each session was a waste of time.

I uniform primer pocket on new brass one time and then do not do anything further.

Lapua brass cleans up very little.
Starline brass sometimes has a narrow pocket.
Remington, Federal, and Winchester can be anywhere depending on the lot number.
What little National Match brass I have cleans up very little.

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 30 July 2024

7fan Exactly how I do it, also.

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Wm Cook posted this 30 July 2024

After picking at this for the past day I've drawn a couple conclusions.

Uniformers come in two designs. One is a fixed height (.030 on the LR uniformer I have) while others (K&M) are adjustable. A fixed height uniformer is no better than many of the primer pocket cleaners that have the four blade cutter design. Both the uniformer I bought and my Lyman cutter are about .030. Put either in an electric drill and under pressure you would remove brass and uniform the base.

If you were fanatical enough that you absolutely had to have a perfectly flat primer pocket base your only option would be to start with and adjustable uniformer. Using either a Precision Primer Gauge (www.accuracyone.com) and or just trial and error with a handfull of brass should give you a uniform pocket. All the brass I have on hand (Winchester .1278, Sig .1265, Lapua .1276 are shallow enough that they could be deepened. My Federal primers average .1278. The target is to have the pocket depth .006 deeper than the height of the primer before seating. With the crush from seating (.002 - .003) that should put the face of the primer .009 below the face of the case.

I'll pass on that for now. But, (there's always a but isn't there) if it were mid winter and I was prepping a few hundred pieces of Lapua brass for competition......well I just may have to give it a go. Because of health in the family I haven't shot a group since last year and I'm getting a bit of cabin fever. But Chris is doing well and I should be shooting again by mid August.

Back to primer pockets. After getting this far I looked at my Lapua .308 Palma SR brass. The difference in primer pocket quality was day and night different than the LR Lapua brass. The SR primer pocket base was flat as a pool table and either the Lyman pocket cleaner or the uniformer wiped out the buildup slick as a whistle.

Thanks, BIll C.

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Wm Cook posted this 31 July 2024

Hey Rick, SevenFan; did I have that right:

Using either a Precision Primer Gauge (www.accuracyone.com) and or just trial and error with a handfull of brass should give you a uniform pocket. The target is to have the pocket depth .006 deeper than the height of the primer before seating. With the crush from seating (.002 - .003) that should put the face of the primer .009 below the face of the case.

Bud, what uniformer tool do you use and do you deepen the pocket to square it up"

I uniform primer pocket on new brass one time

Thanks, Bill.

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.22-10-45 posted this 31 July 2024

I use the solid carbide Whitetail pocket uniformer in both small and large rifle. These are non adjustable. I uniform pockets on new unfired brass. Using cast loads in .22 Hornet and .40-70 straight, which are by no means high pressure loads, after each firing, brass is being removed from pocket bottom. It seems a case not only lengthens after firing but metal is also flowing backwards.

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lotech posted this 31 July 2024

I think I have every Sinclair tool that has to do wth primer pockets, flash holes, etc. I used them years ago with accurate rifles and could see no accuracy difference with or without their use. It appeared to be nothing but busy work for me but I'll certainly not argue with someone who has realized an actual proven benefit with the use of these tools. I did start using a 21st Century priming tool a number of years ago for priming everything and won't go back to anything else.

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Bud Hyett posted this 31 July 2024

Bud, what uniformer tool do you use and do you deepen the pocket to square it up"

Redding tool with the wide shoulder to control depth.

I push the tool down to the shoulder and check the cut.

The tool often cleans the bottom of the pocket a few thousandths (makes the bottom shiny) to zero cut. The cases without cleanup are set aside and run again checking for burrs or ridges on the face that could hamper the cutter for depth.

I never intentionally deepen a primer pocket.

Farm boy from Illinois, living in the magical Pacific Northwest

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Wm Cook posted this 31 July 2024

Bud thanks.

Lotech brought up the 21st Century primer. That one and others have adjustments to limit the travel that the primer rod has to push the primer into the pocket. My K&M & RCBS’s I have (had) require the user to feel the primer hitting the bottom of the pocket. I have a Sinclair in shipping that may or may not have the limiting screw. The original had a screw if I remember right. Not as cool as the 21st or the Franklin. I’ve got real tight pockets on the LR Lapua brass. Part of it was because the plastic shell holder on the RBCS had been wallowed out and the primer rod wasn’t aligned with the primer pocket. That caused the primers to ding up the primer pocket opening and made passage difficult.

Seems to me that you have to have pretty consistent pocket depth to be able to adjust the in or out of the primer stroke to the thousands.

And for the life of me I can’t remember having a pocket cleaner that always cleared the burnt residue at the bottom of the pocket to the point I could see brass. The Lapua Palma brass I spoke about earlier is the closest I’ve ever come.

Not that this means much in the hierarchy of things that control accuracy. Thanks again, Bill C.

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RicinYakima posted this 31 July 2024

I always found it interesting that after resizing my 30/06 cases in the Wilson press in full length resizing die, that the case head was not always 90 degrees square to the walls of the case.

Working with once fired in my chamber brass, I full length resized, removed the case and put it into the Wilson case holder and turned it backways in the Wilson case length cutting tool. I then cut the case head square to the sides of the case. Only then turned around and trimmed to my length.

For my 1903 Springfields, I only had to do this once. On commercial rifles, the chambers may not be 90 degrees to the bolt face, so this will not work as the case bends every time fired.

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Wm Cook posted this 31 July 2024

“ I always found it interesting that after resizing my 30/06 cases in the Wilson press in full length resizing die, that the case head was not always 90 degrees square to the walls of the case.”

Keeps us young does it not. I didn’t know Wilson had a press. Just arbors.

Reversing the shell holder and cutting the case face was a gutsy move and you make it sound easy. Makes my primer pocket problems seems the easier of the two.

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RicinYakima posted this 31 July 2024

Sorry, the sentence was misleading. "press-in" die that is used with an arbor press.

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RicinYakima posted this 31 July 2024

“ I always found it interesting that after resizing my 30/06 cases in the Wilson press in full length resizing die, that the case head was not always 90 degrees square to the walls of the case.” Keeps us young does it not. I didn’t know Wilson had a press. Just arbors. Reversing the shell holder and cutting the case face was a gutsy move and you make it sound easy. Makes my primer pocket problems seems the easier of the two.

Cutting 0.003" at times removes 50% of the surface. Cutting 0.005" would sometimes remove almost all the stamping on the head. At the 22,000 CUP I shoot at, that much increased headspace to fireform the shoulder is nothing with the Springfield claw extractor.

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Sevenfan posted this 31 July 2024

Hey Rick, SevenFan; did I have that right:

Using either a Precision Primer Gauge (www.accuracyone.com) and or just trial and error with a handfull of brass should give you a uniform pocket. The target is to have the pocket depth .006 deeper than the height of the primer before seating. With the crush from seating (.002 - .003) that should put the face of the primer .009 below the face of the case.

My Sinclair uniformers have fixed depth carbide cutters and has been so long since I bought them I don't remember what depth they cut to. If you wish I'd be happy to measure them.

Likewise, used the Sinclair hand priming tool for many, many years but the one at a time got to be too tedious for loading match rounds and switched to an RCBS bench prime tool about 5yrs ago. Meets my needs just fine.

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John Alexander posted this 31 July 2024

Don't want to upset the tone of this thread but has anybody ever seen, heard of, or done themselves any shooting test that show that modifying the primer pocket or flash hole or cleaning the gunk out between reloads has the slightest effect on group size?

I don't mean to be a smart ass but somewhere in the thousands of hours we spend picking nits shouldn't we find time to confirm our favorite ideas by shooting groups with and without and try to find out?

Maybe if it goes bang that's as good as it gets. I don't think we know.

unnamed BOD member

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pat i posted this 31 July 2024

I have been known to clean and uniform primer pockets now and then but don't make it normal maintenance or prep. As long as the primers's not noticeably sticking out of the case I don't think it would make any difference. I imagine for the jacketed bullet BR shooters looking for groups in the 1s making everything as consitent as possible might be something they strive for but for most people I doubt it would make any difference at all. Unless that is like John suggested someone tested it and can prove otherwise.

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Tom Acheson posted this 31 July 2024

Confession time....I have most if not all of the gizmos, tools, devices, etc. that most all of us here most likely own, including an equal number of books by "famous" shooters. I started with a NEECO runout tool and sprinboarded from there. After driving myself nutz trying to determine if the use of all of the tools really helped, including trying to determine if my targets were telling me the truth, I decided to walk away from "gizmo land". I hope to stumble across a swap meet someday where these things are going to consume some table top space.

Maybe it's a simple question.....DO I KNOW (and how do I know) all of these tools and their use will mprove my groups or DO I JUST THINK they will help?

Not trying to be contrary, just sharing a different perspective.

Tom

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OU812 posted this 31 July 2024

The RCBS primer pocket brush chucked in a drill works quickly. It does not get pockets perfectly clean, but its good enough for more consistent primer depth I think.

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RicinYakima posted this 01 August 2024

"Maybe if it goes bang that's as good as it gets. I don't think we know."

John A.,

A few years ago while discussing this topic, I wrote that it made me "feel better" about my reloads. And you replied "Confidence has a lot to do with it."

I have lots of time and do every trick I can before a big match. It probably doesn't hurt anything.

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Wm Cook posted this 01 August 2024

Don't want to upset the tone of this thread but has anybody ever seen, heard of, or done themselves any shooting test that show that modifying the primer pocket or flash hole or cleaning the gunk out between reloads has the slightest effect on group size?

Nope John, no one has that in tested the theory. As long as the primer is seated square and flush to the bottom of the pocket I don't think the primer gives a hoot if there's residue between it and the case or not. Nor if the pocket is not perfectly flat. Same same with those hand loaders that turn their necks, full length size them for a production class rifle. But everyone's wired a bit different so if any of that makes you feel good about yourself go for it. There are some that tinker with things just because it's interesting. Or because it scratches that engineering itch they have. Or they just enjoy piddling with stuff like that.

The question is what would you say to a new shooter that was interested in accuracy. What would you recommend them to do and what not to do. Squaring primer pockets is no where the top of the list. What to recommend is a huge subject that ends at the bench and what equipment their using. Why spend $ on a primer pocket Uniformer when you're using sand bags. In the same context why uniform or clean primer pockets if you haven't figured out bullet to throat/bore fit. Yet like Tom said, most of us chased hand loading, bench equipment and casting gimmicks throughout our lives. Fred Sinclair was a genius of throwing new things at us. As you get older you settled into a pattern of finding the tool and methods that work.

On the rifles that I expect to shoot accurately I buy Lapua brass in lots of 200. What would I recommend to a new shooter that wanted to compete? Lapua. Those 200 pieces of brass will last me years so its sort of a long term relationship. I always prep the brass and that includes neck turning.and flash hole de burring. I neck turn because I neck size. Would I recommend weighing bullets +/- .X grains, primer pocket uniforming, turning necks that will be FL sized to a new shooter. Heck no. Time and money is much better spent on the right casting, hand loading and bench equipment and learning the right casting, hand loading and bench practices. Neck sizing the brass, hand seaters, a solid heavy front and rear rest and a couple flags would be my first recommendations. That and spending an inordinate amount of time understanding how the bullet fits the throat/bore.

I started this thread because I was clueless on the subject. A could days later I've come away with this. For me, primer pocket prep on cases that will be used with high accuracy expectations makes sense. Adding the time to uniform the primer pocket is minimal in both cost and time spent. Once done I'll be able to wipe the pocket clean with the same tool that uniformed the pocket.

What I learned, what I would recommended to myself last week this time:

Seven and Rick was right. Buy the K&M Uniformer. It comes adjusted for the size primer you'll be using. LR comes in at .131 and all of the various brass I have runs .125 to .129. As shipped the K&M will clean up all of my brass.
The K&M Uniformer has a quick release 1/4" hex shank for a hand drill.
The K&M Uniformer has a wide face that covers case head. The Burstfireguns has a smaller diameter and it marred the case head.
You can use that same tool to wipe the pockets clean when reloading.
The tool is adjustable but K&M recommends that if adjustment is needed, contact them before you DIY.
K&M has a video that even I could understand.

At a match you get into a rhythm coming back from your relay. Wipe the necks with 0000 steel wool, a quick brush stroke inside the case necks, neck size the brass, clean out the pocket, prime the brass, de burr the case mouth. The second step is to drop powder and seat the bullet one round at a time. Then go out and stare at the flags. Prepped brass is just a foundation and its cost and time effective. My opinion only, everyone has their own and I respect that.

Thanks, Bill C.

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MarkinEllensburg posted this 01 August 2024

I don't know who the unnamed BoD is that Ric mentions. New brass I take the time to uniform the primer pockets and the flash hole. However with Lapua brass for my .30 Br I did neither. I formerly cleaned rifle primer pockets; I had one, then two rifles and rarely shot even a box of 20 at each trip to the range. I had enough excess free time for those steps.I'm skeptical as John Alexander as if it really matters on the target.

@pat i. I've never shot a group in the .1s! I have shot one 10 shot 100 yard hunter rifle screamer. To me that is noteworthy. I may have cleaned the primer pockets before that. I don't remember. I have gone back to cleaning them based on using Remington primers that are harder to seat. Cleaning pockets has seemed to help with that issue.

@ Wm cook your post and your topic creep. What I would tell a new shooter to cast bullets might be different from what I would tell a new competitor. That said free advice usually being worth what you pay. Cast bullets as best you can, good fill out and good clean bases with no visible voids. shoot lots of groups in practice to dial in the best combination you can find with a bullet and rifle. Go with what you have with confidence and concentrate on the fundamentals on each and every shot. Bev Pinney is a great example, every single shot is a match all by itself, is a philosophy credited to him. Adopt that. IMHO Bench technique is 98% of the game. Every single shot make it count. The few times I have had great groups, for me, have been one shot at a time, intense concentration on the basics of trigger control and sight picture and sight alignment. Above all keep an open mind and enjoy the match.

In keeping with the OP. I load my pistol cartridges on progressive machine. AS such I do not worry about primer pockets. Granted I am not shooting bullseye. Granted I'm not striving for ultimate accuracy either. MY father shot competitive bullseye for years prior to CBA Rifle and never cleaned a primer pocket that I am aware of. He may have started doing so later, not sure.

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RicinYakima posted this 01 August 2024

"I don't know who the unnamed BoD is that Ric mentions."

John Alexander, President of Cast Bullet Association.

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RicinYakima posted this 01 August 2024

"Bev Pinney is a great example, every single shot is a match all by itself, is a philosophy credited to him. Adopt that. IMHO Bench technique is 98% of the game. Every single shot make it count. The few times I have had great groups, for me, have been one shot at a time, intense concentration on the basics of trigger control and sight picture and sight alignment. Above all keep an open mind and enjoy the match."

Truer words never written.

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John Alexander posted this 01 August 2024

Most of the time when I write one of my contrarian rants ( weigh sorting bullets, cases, primers is a waste of time, cleaning cases, primer pockets, inside necks is a waste of time, etc.) I include a disclaimer. "if it gives you confidence it may be worthwhile" or "it's a hobby for heaven's sake, if you like sorting bullets to 0.05 grain or under a 50X microscope by all means keep right on doing it and to hell with what others think." I am not the least bit interested in telling shooters how to practice their hobby. Just please don't tell beginner CB shooters that something must be done unless you KNOW it improves groups. I didn't include those disclaimers above and I am sorry that I may have offended some.

The disclaimers leads to me often asking things like -- if you think slightly rounded edges enlarge groups why in heck don't you shoot groups with and without and find out before telling folks you need to throw them all away. I don't hear a good answer to that question.

John

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Tom Acheson posted this 01 August 2024

John,

Don't worry about offending anyone. This is a HOBBY. If reading someone's opinions and suggestions offend you.....then tough bananas!

Tom

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OU812 posted this 02 August 2024

What is one thing you would tell a beginner CB rifle shooter that you know improves groups.

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Tom Acheson posted this 02 August 2024

Bullet fit to the chamber.

Tom

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pat i posted this 02 August 2024

What is one thing you would tell a beginner CB rifle shooter that you know improves groups.

Pull the trigger. Less worrying and more bench time.

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RicinYakima posted this 02 August 2024

As I have written many times here, and other places on the internet, the best use of your time is at the bench practicing with your best reloads. When I was shooting Military matches, the least amount of practice shots during a season was 500, and all with the same load.

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Sevenfan posted this 02 August 2024

I started this thread because I was clueless on the subject. A could days later I've come away with this. For me, primer pocket prep on cases that will be used with high accuracy expectations makes sense. Adding the time to uniform the primer pocket is minimal in both cost and time spent. Once done I'll be able to wipe the pocket clean with the same tool that uniformed the pocket.

What I learned, what I would recommended to myself last week this time:

Seven and Rick was right. Buy the K&M Uniformer. It comes adjusted for the size primer you'll be using. LR comes in at .131 and all of the various brass I have runs .125 to .129. As shipped the K&M will clean up all of my brass.

The K&M Uniformer has a quick release 1/4" hex shank for a hand drill.

The K&M Uniformer has a wide face that covers case head. The Burstfireguns has a smaller diameter and it marred the case head.

You can use that same tool to wipe the pockets clean when reloading.

The tool is adjustable but K&M recommends that if adjustment is needed, contact them before you DIY.

K&M has a video that even I could understand.

At a match you get into a rhythm coming back from your relay. Wipe the necks with 0000 steel wool, a quick brush stroke inside the case necks, neck size the brass, clean out the pocket, prime the brass, de burr the case mouth. The second step is to drop powder and seat the bullet one round at a time. Then go out and stare at the flags. Prepped brass is just a foundation and its cost and time effective. My opinion only, everyone has their own and I respect that.

Thanks, Bill C.

Not everything we do in life is motivated by time or purpose, some things we simply enjoy doing. Whether running my pocket uniformer in my brass every time matters or not I still do it, it is part of my process I enjoy doing. Is it time consuming? No.

Started prep on 100 new Starline 30-06 brass yesterday, 1st step is pockets and that took 6mins. Nothing else in my process is quicker. I don't advocate to others things I do that, in my mind, may or may not matter one iota as to performance on target.

My continuing struggle with 7BR is a perfect example, I have yet to find "the" combination yet I persevere.

Primer Pocket Prep

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