Geri said:
Match headspace for 22 lr posted as .0425", I have read that in the past some
smiths were grinding the bolt face to .0400". Could this cause a slamfire, or
is this just a tighter headspace? Thanks.
Well, it's both. Ruger tends to set the headspace on 10/22 bolts a bit longer than they need to be, so I and many others will
verify and set bolt headspace to around 0.0430.
It's an easy process to check your cartridge rims, if you have a dial or digital caliper, and you really don't need a "special tool". A live .22 Long Rifle cartridge will fit inside the neck of any fired .22 centerfire cartridge case:
First, measure the over-all length of the fired cartridge case:
Then, zero out your calipers:
Next, insert any .22 Short, Long or Long Rifle round into the fired case and you can get the cartridge rim thickness:
One thing to keep in mind is, the folded over case rim, metal thickness, which will vary a bit. The primer mix is inside that folded metal rim and the rim MUST be crushed so the igniter in the primer mix can detonate the primer and start the gun powder burning. Normally, we don't know how thick the metal is where the case is folded over, so it makes for good practice to be careful and not reduce bolt face depth at the front of the bolt any lower than 0.0430 thousandths of an inch. As rim thickness varies, so does primer ignition and that most often will affect accuracy to some degree. Now, if that doesn't mean much to you, then just buy the bulk boxed .22 rimfire ammunition and enjoy your Ruger 10/22 as is.