uniforming primer pockets?

[Curt]

Are uniforming primer pockets with a tool like Sinclairs a must for a AR service rifle?

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[P. Greaney]

I believe the rationale for uniforming primer pockets is that it provides for the uniform seating of the primer and ensures that the primer does not protrude above the base of the cartridge case.
The first reason ensures that the primer does not move forward when struck by the firing pin as it is seated firmly in the pocket and the second reason ensures that the primer does not protrude boyond the base of the cartridge case and you do not get a "slam fire" when the bolt moves into battery.

I don't believe it is necessary, but consider that I just spent several days uniforming the primer pockets of three thousand cartridge cases with the Sinclair tool chucked into a hand drill.
I don't know any serious high power competitor who doesn't uniform primer pockets of the ammunition that they reload and use in competition.

[Mudcat]

I don't know any serious high power competitor who doesn't uniform primer pockets of the ammunition that they reload and use in competition.

Dang....I wonder how I made it as far as I have and have never uniformed a primer pocket! Must be lucky I guess....or not a serious high power competitor.

John

[P. Greaney]

Dang....I wonder how I made it as far as I have and have never uniformed a primer pocket! Must be lucky I guess....or not a serious high power competitor.

John

I would imagine that you made it as far as you have by shooting instead of spending time uniforming primer pockets. I would further speculate that luck did indeed play a part, albeit a minor one. As to how serious you are about the sport, based on what I have read of what you have posted in the past, I would regard you as devoted to it.
Last, I don't know you.

[Mudcat]

I would imagine that you made it as far as you have by shooting instead of spending time uniforming primer pockets. I would further speculate that luck did indeed play a part, albeit a minor one. As to how serious you are about the sport, based on what I have read of what you have posted in the past, I would regard you as devoted to it.
Last, I don't know you.

Heehee...I was just messin. To be honest, I did actually uniform my first primer pockets about 2 weeks ago at the insistence of a fellow HP shooter as we were processing brass in his workshop. THe pockets look nice, the primers seat in deep, and with at least one of them I tried to fire this past weekend at a LR match, apparently seated too deep and didnt get a good firing pin strike. Also had 10 ring or more elevation issues with that ammo and cases...but, it was a new load so I am not chalking it up to that...yet....but I do believe it cost me the win (3 pts out).

In any event, uniforming primer pockets isnt a bad idea, probably a good one, but I do not believe its anywhere near necessary or required. FOr me, its too much time and effort that I dont have and I would rather spend the time I do have pulling the trigger.....more fun!

John

[Maury Krupp]

"Required?"

To make ammo that will hold the 10-ring? No.

I know enough shooters like John who can dump fired cases in the hopper at one end, pull the handle, then go shoot match winning scores with the ammo that comes out the other end.

To prevent slamfires? It doesn't hurt.

But preventing slamfires has so many components that to isolate one probably oversimplifies things.

I use a Sinclair uniformer to clean the pocket as a routine part of case prep. It's quick and easy and makes me feel more confident in the safety of my ammo.

Maury

[MEHavey]

I started uniforming when I began getting high primers in S&W500 brass a while back. (So high I had trouble getting them out of the shell holder on occasion.) That made me more sensitive to the fact that more brass seemed to producing more high primers as a rule of late. `Don't know when except the pocket corners don't seem as cleanly swaged "...as in the old days."

When I started reloading for both the AR and the Garand it just became do-it-everytime.

[Curt]

I am trying to get my WSR primers to exist in my R-P brass and Win brass. I had been uniforming the pockets but i think that is is adding to my problem ever so slightly. I have backed my load down 6/10's of a grain and I have stopped losing primers but still have significant push back of the primers.I ordered a chronograph to see what these things are really doing.I am close to a full grain under max load for a 77 SMK. I put a primed case in my rifle yesterday to test a new firing pin, I placed the muzzle against a folded towel on the floor as to not scare the dog and the primer backed out almost completely.
The down side is I would have better luck at winning the lottery than finding other brands of small rifle primer to try. I am sitting on 10K wsr's I bought at Perry last year and have about 2K each once fired R-P and Win brass I bought from the local police range.Now my salary got cut and my budget is shot so I am just hoping this works for the season. I am out of patience and funds.

[John Kepler]

I put a primed case in my rifle yesterday to test a new firing pin, I placed the muzzle against a folded towel on the floor as to not scare the dog and the primer backed out almost completely.

From an old R&D "Lab-Rat": Sometimes, bad indicators are giving you a window into the "real world"....other times, a bad testing design telegraphs the flaws in that testing system rather than ANYTHING going on in "the real world". In the case above, you have an absolute primer in the later rather than the former!

To begin, in the situation articulated, I'd be VERY surprised if I did NOT get the results you did with PERFECTLY seated primers! You've set up a situation where the primed case will generate enough bore-pressure to slightly open the bolt, but not enough to pressure-seat the primer. The result is a pushed primer each and EVERY time! You MAY have a primer-pocket issue....but that test doesn't prove or disprove the theory!

[MEHavey]

>
> "...but still have significant push back of the primers....."
>

That sounds like a headspace issue, not a primer/seating problem.

>
> I put a primed case in my rifle yesterday to test a new firing pin, I placed
> the muzzle against a folded towel on the floor as to not scare the dog and
> the primer backed out almost completely.
>

"...almost completely..." ? Heavy duty.... headspace, either the rifle or (more likely) your sizing die setup relative to your rifle's working headspace. The amount that the primer is backing out is a measure of the excessive room your case has relative to the bolt face after the firing pin kicked it forward. I'm (kinda) surprised it fired at all if that's the case.