captaincaveman said:
what shims do I need and where do I find them?
OK finally getting time to get to this.
Headspace of the lack of can be one of the biggest reasons that a primer from the battery cup is forced up into the hammer hole in the face of the bolt.
If you look carefully at this picture of a Knight NFPJ Breech Plug you can see the SS shim installed in the bottom of the primer pocket to achieve a 'primer crush' and 0 headspace with a given primer. And in my case it is modified to accept W209 primers.
Most new rifles in the Mountaineer series and possibly the new Extreme series have a much tighter 'tolerance' on the depth of the breech plug pocket in the barrel. On the other hand older rifles like the Original DISC the tolerance level was much lower. In those days no-one thought about a clean breech. I have two Original DISC's that the breech plug need to be shimmed to 0.025" to achieve 0 headspace. Even older DISC Extremes/Elites can vary by as much as 10-15 thou.
It seems to me the new Mountaineer series can vary but 0.005" and some will require shimming. Not all of this is dependent on the depth of the BP hole. If the bolt length is off just a little it will greatly effect the head space. Even the rear of the bolt and how it closes can effect headspace. So it really does not have to be one thing.
It really helps if you determine the measurement of what shims you might need to fix your problem before you start shimming. The shims for this process come in 3 thicknesses and 2 OD sizes that you can use.
OD sizes.... there are a group of shims with an OD of 0.241" that will drop right into the primer pocket. With these shims you can just keep adding shims until you feel the primer crush. Then add up the number of shims you have installed and you will know what you might need. The 0.241" will then fall out or can be easily pulled out to empty the primer pocket.
The second OD size shim is a 0.248" shim and will/can pressed into the primer pocket. This shim will stick and stay in the primer pocket - you will not be able to remove it. So before installing these shims make sure you know the size you need to use.
This is a package of 0.0248" x 0.032" shims -probably a size you will never need but they are available.
This picture shows a 0.0248" x 0.005" shim inserted in the top of a BP ready to be driven down with a spent 209 primer and a plastic mallet.
This link should carry you to the McMaster-Carr catalog page for the correct shims
http://www.mcmaster.com/#catalog/118/3249/=10geukw
For the 0.241 OD shim look in the group of shims labeled -> 18-8 Stainless Steel. Three sizes 5 - 16 - 30 thou thickness. I see no reason to get any 0.030 shims, followed only a few would ever need 0.016 shims. The 0.005 is probably the best all around for testing to achieve the correct fit.
For the 0.248" OD shim look in the -> Spring Steel section -> for shim thicknesses of 5 - 15 - 32 thou. These shims can be pressed in for a permanent fit.
An easy way out of all of this is to use high pressure rubber "0" rings... they normally last about 50 shots.
Achieving 0 to near 0 headspace is a real desirable in my mind.
