Proud Primers

[trucraft]

I have had this issue with the brass from new. Now on second firing and still my primers are very slightly high, enough to make the bolt stiff to close.

I am using Norma 300 SAUM brass and BR2 primers.

I uniform the pockets with a Sinclair carbide cutter after each firing. This uniformer worked perfectly with my .243 brass leaving the same batch of primers just below the head of the case.

I have measure the uniformed pockets and the primers and the pockets are 8-10 thou deeper than the primers.

So all I can think is that its my RCBS priming tool or a dodgy shell holder.

 

Anyone have any ideas?

 

I don't have another shell holder or priming tool to swap yet.

[jcampbellsmith]

Can I suggest trying a new Sinclair carbide cutter? I wouldn't chamber any rounds in a rifle when the primer was sitting proud. Regards JCS

[gbal]

+1 on JCS

 

You can measure 'primer seating depth' uniformity,relative to cartridge base,by holding the primed cartridge case on the 'other end' of a micrometer,at zero,and very gently easing the micrometer out until the 'slider' touches the primer. See "Accurate Shooter" tips,for description,though it is simple.

[trucraft]

+1 on JCS

You can measure 'primer seating depth' uniformity,relative to cartridge base,by holding the primed cartridge case on the 'other end' of a micrometer,at zero,and very gently easing the micrometer out until the 'slider' touches the primer. See "Accurate Shooter" tips,for description,though it is simple.

I have tried this but am finding it very hard to get an accurate reading as the surface of the primer is a difficult platform to hold the base of the calipers on. Checking the depth of the empty primer pocket in the same way is easy as the caliper base sits square on the case head.

 

JCS,

I have been toying with getting the 21 Century adjustable cutter.

But according to my measurements the problem is not the primer pocket depth.

Perhaps the width it tight?

[gun nut]

If your primer pockets are deeper than the primers and they are still finishing up proud, then its you hand primer/ shell holder combo at fault. When you close the hand primer the ram is not pushing up far enough to seat the primer properly. I have had the opposite issue on 2 calibres where the ram actually crushes the primer if the handle is squeezed all the way in. Try another shell holder first as that's the cheapest to replace, and also the most likely culprit.

[gbal]

truecraft .....true! it is a tad fiddly,practice helps-but not as much as three hands,better yet a vice...the great advantage is that you get a measure of the primer in place,which is after all,what matters.And if it's consistently the required few thou' deep(.004 maybe) there is nothing wrong with your other equipment/technique,or pockets in all probability. Guages are made,some rather pricey-K&M $134:21st Century adjustable depth primer seater is similar price,with one head.Most don't need.

[trucraft]

So I just found another shell holder and had a go with that in the priming tool.

Not much different. If I hold the primed case on a straight edge I can just see light underneath as well as rock the case. So very slightly proud.

[gun nut]

Trucraft,

 

if you take your hand primer apart, can you shim inside the cup that rides between the ram and the ball ended rod connected to the handle? some tin foil would do as its only to see if the primer will then seat properly? If it does you need to get a new, 4-6thou longer , ram or more likely the cup that it rides on.

[trucraft]

Trucraft,

 

if you take your hand primer apart, can you shim inside the cup that rides between the ram and the ball ended rod connected to the handle? some tin foil would do as its only to see if the primer will then seat properly? If it does you need to get a new, 4-6thou longer , ram or more likely the cup that it rides on.

I was thinking the same thing. I will have a crack at it tomorrow. Thanks.

Any idea who would sell rcbs primer components?

[trucraft]

GunNut,

I just put a shim in the cup part of the ram and seated a primer.

Perfect!

Primer now sits just below level.

Unfortunately the shim is not a long term solution as it is likely to compress over time.

At least I know the problem now and can call GMK to see if they have any spares.

 

Thanks guys for all the input.

[jcampbellsmith]

I may be barking up the wrong tree, but here goes. Is the shell holder you are using in the RCBS priming tool the correct one for a 300 SAUM?

 

http://www.midwayusa.com/find?dimensionids=13245

 

http://www.handloads.com/misc/shellholders.asp

 

Regards

 

JCS

[gun nut]

Trucraft,

its often the simplist solution that works the best, too many times people overthink problems

[skull hooker]

You've probably done this already but try rolling the primer seating rod on a flat surface. It will show if its been bent slightly and so wont seat the primers deep enough.

[dorg]

Had same problem a hornady priming tool just packed it to make the priming ram protrude abit further. Its all to do with the thickness of the case rim. Get a Sinclair hand priming tool , due to the fact you tighten the case in the shell holder it seats every primer exactly the same depth below.