Primer Preload Test

B

Bart

Member
I'm not going to write an article on this but, I did a little experimenting while shooting my 6MM Dasher!

Findings:

1. Nothing good happens until the primer touches the bottom of the primer pocket! I started with primers seated as far out as possible and worked my way in using a priming tool that I bought from PMA tool. The tool has tactile clicks so it's very easy to adjust and incrementally change the primers seating depths .002 per click.

2 Primers with a slight amount of crush shot just as well as primers that were seated just touching! Slight amount being .002 to .004, after that groups started getting erratic and opening up!

The primers that I used were small rifle CCI 450 Magumums.

Conclusion: I really like my 21 Century priming tool from PMA! It took a lot for me to give up my old K&M!
Y'all didn't see that coming!

Later
Bart
 
Bart,
Ditto on the 21st Century priming tool. It is a piece of art. Thanks for sharing your results. I feel all better now, since I have been going past touch virtually all of my reloading life, but had never done any testing. After your last post, I was about to redo my process. I may do a little depth measurement to see what my typical squeeze produces past touch.

For those of you that are reloading at home, are not in a hurry, and would like to have more feel, the RCBS priming tool that screws into the top of the press like a die, and takes regular shell holders, for one at a time priming, when properly adjusted gives excellent feel....the trick is to set the "die" depth just right. A little testing should determine your best adjustment.
Boyd
 
Ive also experimented using the k&m with depth dial indicator and found the same results me and bart already knew. A ppc likes a touch to .002 crush- nothing more nothing less. I think that if the firing pin seats the primer at all like before touch before it sets it off there is weird vibrations akin to ignition problems actions have.
 
Thank You Bart. I primed some with .000, -.001, -.003 (getting .-003 was tough to get consistant) so I don't expect this to be a good setting for my combination.
 
Last edited:
i think that is what i said.

and for the record, yes i copied it from your infamous "mike in co".

he said it in a thread years ago. before i joined and was just a reader.

it appears he was correct way back then.
 
Bart said:
I'm not going to write an article on this but, I did a little experimenting while shooting my 6MM Dasher!

Findings:

1. Nothing good happens until the primer touches the bottom of the primer pocket! I started with primers seated as far out as possible and worked my way in using a priming tool that I bought from PMA tool. The tool has tactile clicks so it's very easy to adjust and incrementally change the primers seating depths .002 per click.

2 Primers with a slight amount of crush shot just as well as primers that were seated just touching! Slight amount being .002 to .004, after that groups started getting erratic and opening up!

The primers that I used were small rifle CCI 450 Magumums.

Conclusion: I really like my 21 Century priming tool from PMA! It took a lot for me to give up my old K&M!
Y'all didn't see that coming!

Later
Bart
Click to expand...

Thanks Bart, just ordered one. They are probably three months behind after your recommendation though. :)
Charlie
 
Thank you for sharing this info Bart. Two questions (maybe I'm just not thinking today) :confused:
1. How do you know where just touching is on a primer/primer pocket? Do you mathematically figure it out then measure? (that only counts as 1 question :)
2. Are primers uniform enough to just "set it and forget it"?

Thanks in advance for any replies.

Stanley
 
Apollo said:
Thank you for sharing this info Bart. Two questions (maybe I'm just not thinking today) :confused:
1. How do you know where just touching is on a primer/primer pocket? Do you mathematically figure it out then measure? (that only counts as 1 question :)
2. Are primers uniform enough to just "set it and forget it"?

Thanks in advance for any replies.

Stanley
Click to expand...

Stanley,

1. I can feel the primer contact the bottom cup.

2. Probably so, but I gentle seat the primers until I feel them touch. Then I stop. You could set the 21 Century priming tool for .002 past just touching. That you could set and forget.

However I think it's best to have a priming tool that will give you some "feel".

Bart
 
A long time ago you had to work on the brass to have a primer pocket where you could feel the primer touch bottom. I suspect you still have to do that but don't know for sure.....
 
The first Lapua .220 Russian brass that I used had too large of a radius at the bottom corners of the primer pockets, and this prevented primers from seating properly. Russ Haydon used to sell a fixed carbide tool that cut the pocket corners to allow proper primer seating. Cases that I bought later did not require its use. The regular Sinclair pocket cutter would bind up before it hit bottom in those early cases. They were not designed to cut on their sides. The Haydon cutter was probably made just slightly smaller in diameter. the pattern that it cut was only in the area that needed relieving. Mine is in one of my tool drawers and has not seen use for some time. I took a momentary break and measured. The Haydon cutter is .001 smaller in diameter.
 
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