Forster Co-ax priming tool

I also have the Forster press and utilize the priming system on it due to repeatable seating depth of the primer.

I considered the stand alone Forster priming tool but have only read a few positive reports of it and quite a lot of negative ones.

I felt it prudent to avoid it.

If I were to use a seperate priming system it would likely be the Lee hand priming unit.

If I had the money I would swing for the Sinclair model.
I use two of them. One is the old steel version and the latest is for the auminium model. I like the ability to dump a complete pack of primers into their loading platform but it is slow to tun them all up and place into the flat tube. The old model allowed me to adjust the seating depth quickly and I have loaded about 3-4,000 with it. It is a tool and it is not perfect but I have learned to work with it as it will turn the last primer over if you are not careful. When loading the tube -chute into the tool you need to have either a paper clip inserted to hold the primer column or hold with a set of tweezers to keep from dumping the lot on the floor. The old model allows for various seating depths and it works just fine. I also have Lee, Sinclair and RCBS plus the Dillon progressives which are worse for primers that the Forster. Just on Old opinion 73 tomorrow---
Laus Deo
I have the Forster priming tool.
I do not load the tubes with the priming tool, but in an RCBS primer tray with a milled out corner. I clamp tubes to the tray.
I use the AutoPrime II and, while I detest the shoddy plastic crap, I love my press and don't have to fill primer tubes. I can feel the primer seating and definitely know when the seat is solid. It ain't perfect, but I have a process and it works. No primer tubes. I watch the punch pick up the primer; after that, it's money.
I like your idea; can you share the dimensions and the how to's ???

many thanks,


Sorry, I responded with the wrong Forster mod.
Here is the right one:


The slot is milled .050" deep, but it only needs to be .031" deep to match the thickness of the bottom of the Forster primer tube.
The slot is milled .340" wide, but it only needs to be .300" wide to match the width of the the Forster primer tube.
The slot is milled 1.2" long, and that dimension is to match your clamp.
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Hi Clark, sorry to drag up an old thread, but I am tying to do something very similar (although 3d printed rather than modified... however I am still waiting for the primer tubes to come from the US.

Is there any possibility that you could tell me the thickness of the whole tube? and is there any real difference between the small and large tubes in this application?

Thanks in advance,

Dylan :)
Hi Dylan, the outside dimensions of both tubes are 7.15mm wide by 5.75mm deep. The only difference between the LR and SR tubes is the SR tube has a fold down each side running the complete length of the tube. The fold protrudes into the tube so the inside measurement is smaller.
I have been using a Forster Co-Ax Priming Tool for about 10 years and swear by it. IMO, it’s fast, and seating feel and consistency is perfect with any case or primer combo I’ve run through it. Struggled for many years with hand held products from Lee, RCBS, and Redding, Sinclair, etc. This product, along with the Wilson/Sinclair case trimmer, are two of my “staples” for precision reloading.
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