Is it ok to chamfer primer pockets?

[redactor]

I use the primer attachment on my Redding T7 press to prime all of my cases. I've had it for a year, and this is the only thing that I don't like about that press. I use CCI primers, because they were cheap and I bought a couple thousand.

I have often problems with primers not seating deep enough, and worse my primer seating is not consistent from case to case. This is with .45 Auto, .303 Brit, and 7.5 Swiss.

Given that, I've noticed that if I use my chamfer/deburr tool to slightly chamfer the primer pocket, I get deeper and more consistent seating. Is it safe to do this? I've only tried it on a dozen or so assorted cases, and haven't fired any of them yet.

 

[rcmodel]

If done lightly, it won't hurt a thing.

Just don't overdo it!

rcmodel

 

[amlevin]

I find that some brass is manufactured with a real square angle from case head to primer pocket. Almost square without any radius or chamfer at all. On these cases I just run them through my Dillon Superswage 600 and treat them like a Mil-Crimp case. This process adds a slight radius that allows easy seating of the primer, expecially in my progressive press.

 

[ClarkEMyers]

People do it and report that it works.

People do it and report that it works.

It has been commonly done as a way to deal with the GI primer crimp with tools on hand. I'd sort of prefer to use a uniforming tool or a swedging tool rather than chamfer the primer pocket but I'd use whatever tools I had on hand myself.

The only issue I know of is that it makes reading pressure signs from the primer even more of a guessing game - but reading pressure from the primer is a guessing game anyway.

After changing the pocket with a chamfer the primer will tend to appear flatter as the primer expands a little bit to fill the the void created - assuming a void is created by chamfering around the corner of the primer pocket. This does not mean the loads are higher pressure. Also of course it makes the path for water or oil to seep in a little easier - but most people never expose their ammunition to water or oil - don't spray the cartridge or the loaded firearm with an oil.

 

[aka108]

Have some cases of 303 and 30-06 Greek surplus that I chamfer to remove the slight crimp in the primer pocked used on it when new. Never a problem.

 

[darwin-t]

I did a bunch one night.. When I stood up somehow some of those shavings ended up in my eye. I have no idea how that happened, but it skeered me off from ever trying it again.

 

[45ACPUSER]

A slight twist of the chamfering tool works well to remove primer pocket crimps. Using a primer pocket uniformer would ID case that need the use of the chamfering tool..

 

[redactor]

Follow up: Bought an RCBS hand-priming tool last week.

Analysis: I should have done this a long time ago. The hand-priming tool has solved all of my priming problems, and works with both RCBS and Redding shell holders.

 

[TexasSkyhawk]

I chamfer all of my long gun brass, and all of my target handload brass.

Only need to do it once.

Jeff

 

[brickeyee]

You should consider modifying the primer seating punch before altering every case you load.

 

[Encoreman]

I was once told and forgot what degree chamfer tool to use. Anyone got a good idea? Thanks Mac

 

[Walkalong]

It is unnecessary most of the time. For some tight pockets just a couple of light twists will do.

 

[The Bushmaster]

I use my chamfer/deburing tool for those cases that need a more beveled lead for the primer pocket. Works for me

 

[adkpete]

I just had to chamfer a whole batch of privi brass in 7.5x55 I got from Grafs. I used my lyman 50 cal. chamfer tool so it wouldn't bottom out in the primer pocket

 

[243winxb]

Its not OK to chamfer primer pockets, IF OVER DONE, the primer will flow under a maximum load, sometimes blowing out the primer cup causing gas cutting of the bolt face. Winchester primers have a taper on there leading edge that helps guide/center the primer when just starting to seat. CCI primers are sometimes oversize in diameter in small mag pistol primers.