Primers Seat High

[Redhouse]

I'm loading for a 7mm Rem Mag. When seating primers using the RCBS hand priming tool, the primers protrude from flush with case bottom several thou. I have 2 different RCBS #5 shell holders, same result with both. Same tool is fine loading for other cartridges, using different shell holders - primers sit below flush.

I have used ammo made this way, in a rifle I no longer have, without issues. As I'm starting over with a new rifle, I thought I'd ask what if any potential problems I might run into as a result of high primers.

 

[ElmerFudd]

Hmm...

Once fired brass?

Primer pockets cleaned?

What brand of primers? Have you tried others?

Do you have another priming tool? Press mounted perhaps?

How far does the tool push up without brass in the way?

I haven't loaded that cartridge but I don't see why it would be any different. I would be calling the manufacture of the ammo and asking if they had some bad brass.

Have you measured the primer pocket depth? Compared to others?


Fudd

 

[HKMark23]

I've recently read a similar thread where the RCBS push rod was the problem. You may be using the wrong one, (there are 2), or it may simply be too short and you need a replacement. The primers should be flush or below the head surface slightly.

 

[Jarlath]

A raised primer is not recommended at all, but a slight raise MAY not be an issue with slower actions such as break and bolt on CERTAIN firearms. In a semi, raised primers are a really bad thing...

That being said, get a primer pocket brush and clean out the remnants of previous firings. Better safe than sorry.

 

[Redhouse]

Should have clarified....I'm meticulous about brass, as I mainly shoot for accuracy. Pockets are definitely clean, though I haven't measured them for depth....yes, they are previously fired.

I'm still really thinking it's the shell holder....the primers are a tight enough fit, and I am making a complete stroke right to the end of travel of the tool....in other cartridges, I run out of ability to push them in further before the end of travel. What I might try is seeing if the rod is indeed short, put something under it for better compression.....but the same rod seats primers in .308 size cases perfectly.

Ugh, yes I can do press mounted primer seating - forgot about that, actually, as I hate doing it and so never do. I'll give it a shot. Thanks.

 

[ElmerFudd]

7mm Rem. Mag. is a different shell holder than 308 Win.? OK. It sounds to me that it could be a combination of a short push rod and a high shell holder. Perhaps the shell holder is on the high side of the tolerances? Do you have any other cases that use the same shell holders?

How far does the tool push up without brass in the way?

If its not going up as far under load perhaps there is something loose?


Fudd

 

[rnbra-shooter]

I'm still really thinking it's the shell holder....the primers are a tight enough fit, and I am making a complete stroke right to the end of travel of the tool

There's your problem - you're running out of stroke before the primer is fully seated.

(EDIT to add: if you put an unprimed case in your priming tool, without a primer, and close the handle all the way, the rod ought to protrude high enough to make removing the case from the shellholder difficult or impossible. If it doesn't protrude into the primer pocket like this, it isn't protruding enough)

Until you figure out the solution to this (and it sounds like you have a good handle on ie, e.g. rod length, shellholder, etc), you can continue to prime with this tool, but use your press to finish the seating of the primer so that it is correctly below-flush. A lot less "ugh" factor when using your press this way, compared to hand-feeding primers individually, eh?

 

[Redhouse]

There's your problem - you're running out of stroke before the primer is fully seated.

(EDIT to add: if you put an unprimed case in your priming tool, without a primer, and close the handle all the way, the rod ought to protrude high enough to make removing the case from the shellholder difficult or impossible. If it doesn't protrude into the primer pocket like this, it isn't protruding enough)

Until you figure out the solution to this (and it sounds like you have a good handle on ie, e.g. rod length, shellholder, etc), you can continue to prime with this tool, but use your press to finish the seating of the primer so that it is correctly below-flush. A lot less "ugh" factor when using your press this way, compared to hand-feeding primers individually, eh?

That's a good idea, just finish them off in the press. Or maybe I could put a dead primer under the rod to boost the length of travel?

I just ran off 18 rounds thru the gun, so I know they work. Speed was lower than anticipated but that could be a function of many different factors including the primer seat depth but also including the chrony and certainly the rifle itself. In a 7mm Rem Mag, I believe 70 grains of RL22 behind a 140 Sierra Game King should be getting up around 3200fps but was just barely cracking 3000.

 

[rnbra-shooter]

Or maybe I could put a dead primer under the rod to boost the length of travel?

Hey, now you're talking.

I don't know if you mean to put a dead primer between the flat part of the rod and the primer (this would work).

But your question made me think of a better idea (unless you've already thought of this!). On my RCBS hand primer, the rod that connects to the handle has a spherical indentation in it. This contacts a spherical end of the rod that is used to do the primer seating (if you look carefully, you'll see that your primer seating rods are rounded at one end, and flat at the other - the flat one is that one that should be pushing against the primer).

So here's my idea. If you take a *SPENT* large rifle primer, you could pry out the anvil, leaving you with just a cup. You could place this cup between the connecting rod and the rounded end of the primer seating rod. This would raise the rod enough to allow you to fully seat a primer in one go.

I just ran off 18 rounds thru the gun, so I know they work.

It's not a question of working, it's a question of safety. If the primer is protruding, it will take whatever blows you might give it via rough handling (e.g. vigourous chambering). What you want to avoid is a primer going off because it gets bumped while you're chambering a round. While this is less likely with a carefully handled bolt action rifle than with a semi that closes up pretty smartly, its very much an avoidable risk. Seat the primer so that it is below flush, so the case head fully protects the primer from seeing any impact at all. The only time a primer should experience impact is when it is struck by a firing pin.

(actually there also a very minor reliability point too - when the primer is fully seated, the legs of the anvil apply preloading pressure to the primers explosive pellet. This makes it more sensitive, and is supposed to make for more reliable and more consistent ignition.)

 

[Redhouse]

I definitely meant a dead primer under the lower rounded end of the rod, not on top of the flat part and under another primer. Or maybe there's something else I can use for a spacer, but I would think a dead primer would be just right as the outer circumference is perfect to the rod hole. I'd rather have that flat rod surface pushing the primer in, rather than any eccentricities in shape against the live primer <insert kaboom blown up cigar face smiley here>

Hey, now you're talking.

I don't know if you mean to put a dead primer between the flat part of the rod and the primer (this would work).

But your question made me think of a better idea (unless you've already thought of this!). On my RCBS hand primer, the rod that connects to the handle has a spherical indentation in it. This contacts a spherical end of the rod that is used to do the primer seating (if you look carefully, you'll see that your primer seating rods are rounded at one end, and flat at the other - the flat one is that one that should be pushing against the primer).

So here's my idea. If you take a *SPENT* large rifle primer, you could pry out the anvil, leaving you with just a cup. You could place this cup between the connecting rod and the rounded end of the primer seating rod. This would raise the rod enough to allow you to fully seat a primer in one go.



It's not a question of working, it's a question of safety. If the primer is protruding, it will take whatever blows you might give it via rough handling (e.g. vigourous chambering). What you want to avoid is a primer going off because it gets bumped while you're chambering a round. While this is less likely with a carefully handled bolt action rifle than with a semi that closes up pretty smartly, its very much an avoidable risk. Seat the primer so that it is below flush, so the case head fully protects the primer from seeing any impact at all. The only time a primer should experience impact is when it is struck by a firing pin.

(actually there also a very minor reliability point too - when the primer is fully seated, the legs of the anvil apply preloading pressure to the primers explosive pellet. This makes it more sensitive, and is supposed to make for more reliable and more consistent ignition.)

Thanks for the safety reminder too

 

[rommelrommel]

A full dead primer would make the rod too long and probably wouldn't pick up new primers from the feed system anymore.