Primer Length Chart

sabotloader · 02-23-2009, 06:40 AM

Busta spent some time measuring the different primers that he had on hand and creating a table of the infromation. One of the reason was the thought that the length of the primer has a direct relationship to the amount of blow-back material in the breech area...

Here is a copy of his work:

hunting junkie · 02-23-2009, 06:56 AM

Thanks sabotloadernow between this,the sabot chart,and all the rest.It will only take us 5 years instead
of10 to catch up to you guys.

waterdogjoe · 02-23-2009, 03:38 PM

That's interesting info. I've been having problems with a Knight rolling block where it doesn't strike primers hard enough and there are misfires. I sent in the trigger assembly and they replaced it, but I still had the problem. I then found that CCI 209M primers were much more reliable than the Win 777 and Win209ML primers that I tried, and it may be related to the differences in lengths.

After much inspection and consideration of the problem I realized that a primer seated in the nipple contacted the face of the firing pin assembly, preventing the action from closing all the way. A rolling block action rotates down as it is "rolled" back, so the hammer was striking the pin assembly high and preventing a good strike of the pin- I could even see the wear around the hammer and firing pin to prove this. I had the plug out about 20 times making sure that it was clean and seating properly, and after that they told me to send the whole gun in, which I just did the other day.

Where I'm going with this is that I thought that the reason the CCI primers fired more reliably was that they were softer, so that they somewhat masked the problem with the gun. After looking at your chart I realize that the CCI 209M primers average about 0.001" shorter than the other ones I was trying. This could allow the rolling block to come a little closer to the proper closed position and fire more consistently.