Primer Pocket Prep

447 Views
Last Post 02 August 2024
Topic Is Solved

CBA Member

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.

Attached Files

32 Comments

Order By: Standard | Newest | Votes

CBA Regional Director

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

Attached Files

Liked by

CBA Member

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.

Attached Files

Liked by

CBA Member

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.

Attached Files

Liked by

CBA Member

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

Attached Files

Liked by

CBA Member

RicinYakima posted this 30 July 2024

7fan Exactly how I do it, also.

Attached Files

Liked by

CBA Member

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.

Attached Files

CBA Member

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.

Attached Files

CBA Member

.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.

Attached Files

Liked by

CBA Member

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.

Attached Files

CBA Member

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

Attached Files

Liked by

CBA Member

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.

Attached Files

CBA Member

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.

Attached Files

Liked by

CBA Member

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.

Attached Files

Liked by

CBA Member

RicinYakima posted this 31 July 2024

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

Attached Files

CBA Member

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.

Attached Files

Liked by

CBA Member

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.

Attached Files

Liked by

CBA President

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

Attached Files

Liked by

CBA Member

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.

Attached Files

CBA Regional Director

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

Attached Files

Liked by

Standard Member

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.

Primer Pocket Prep

Categories

Search

Popular Tags

This Weeks High Earners

Hot Topics