Are you measuring from the bolt face to the case cavity of the bolt? If so that will likely be the same. However, the bolt face itself may not be making contact with the barrel tenon, and thus adding a bolt shim can possibly shim the cartridge rim closer to the barrel face. I hope I explained that correctly.

 

That’s exactly how I measured but , I’m just saying you would never get a closer headspace than the .044 that the pocket is..

 

You're actually pushing the bolt face closer to the face of the barrel, providing it's already away from it a few thousandths to begin with, which means the rim is also a few thousandths away from the barrel face. By closing the gap between the bolt face and the barrel tenon face, you effectively close the gap between the rim of the cartridge and the barrel face as well.

 

If the bolt face has a little room, then its not pushing shell tight to chamber.

 

If the bolt face is indeed already touching the barrel tenon, then a bolt shim will have no effect on the headspace at that point.

 

Other than to make it difficult to close the bolt.

 

You are absolutly correct. However trying to explain this to some individuals ends up at a stand still. Just use better ammunition and you will be farther ahead.

Many people do not understand that it is necessary to measure the bolt from the bolt face to the depth of the cartridge pocket. They just think that shoving bolt shims in cures all their problems. They do not.

 

Shhhhsshhhh, I make the bolt shims!!! Quiet !!!! 🤣🤣🤣🤣

 

Bolt shims moves the bolt face closer to the barrel.. which means tighter headspace.. if your factory gun has a .044 headspace and you add .002 shim to the bolt you will then have .042 headspace..

 

Not necessarily. If the bolt was already contacting the breech the headspace is not going to change by adding shims.

 

i was just wondering didn’t want to believe I was over thinking what I thought lol.
but confirms my suspicion

 

So you see now that adding bolt shims DOES decrease your headspace correct?

 

mmmmm yes and no ,,,,,,,yes it moves the bolt but does nothing to the rim pocket depth in bolt face .
so I’m happy gives me something else to ponder lol

 

When the bolt face moves forward so does the rim pocket.. which in reality is the bolt face

 

Yes, but if the pocket is .044" deep, how is it possible to get less than .044" head space?

How can you get a headspace dim less than the pocket depth? If the pocket depth on your bolt is greater than the rim on your ammo, how will shims help?

I believe that is the point that the OP is making.

 

How many bolt faces does a bolt have?

 

I’m just guessing ok, 1 ?
did I win?

 

One.. and it's where the base of the cartridge sets..

 

Ok! Then what is that surface that sits .044 in front of that one?

 

Head space is not set by the depth of the case depression in the bolt face. It is a combination of this depression depth AND the distance of this depression from the end of the barrel chamber. In most .22 bolt guns I've owned or worked on, the bolt does not come up hard on the barrel chamber end.

I made this little adjustable cartridge and 1-inch-long chamber. Its purpose is to accurately measure headspace. To use, you back out the fine threaded little screw at the back of the cartridge a little bit at a time. When the bolt starts increasing in closing resistance, remove cartridge and measure its length with micrometer or caliper. The measurement over 1" is the headspace. This in turn give you the info to decide if you want to shim the bolt.

 

That's slicker than a pocket on a shirt. Do you sell these or be interested in making another?

 

My head, you guys are a riot. Love this place.

 

I knew I should of turned left at Albuquerque 😁

 

That's all folks!

 

OHHH GEEEZ! I think I need a bigger hammer. Love reading these threads. Whatta Hobby!

 

I got a little sledge hammer we call the B Beater. I can defiantly advise you get one if you don’t have one already. Fixes everything 🤣

 

Lets say you started at 48. With 4/1000 shims you bottom out at 44. You can remove the barrel and shave 0.001 of the barrel. Then use a thicker 005 shim to get 43. That is min spec. Or stop at 44 if you dont have a lathe or the extractor slot is not deep enough. . Those numbers you measured, 48,44 and 43 are head space.

 

Scotty b,

Sounds like somebody's kid has been watching the self-proclaimed YouTube experts talking about shims.

This topic comes up every once in a while, and you'll get a lot of conflicting answers. It's the same argument as with "what bear gun to use" or "does sorting and weighing ammo improve accuracy."

The only way to know for sure is to test yourself with the shims in and shims out. Holes in paper don't lie! YouTubers need click bait!

BTW I'm in the it doesn't improve accuracy camp! I have tested shims in three different CZ 457 rifles with no conclusive evidence shims produced tighter groups.

YMMV Good luck!

 

Scotty b,

Sounds like somebody's kid has been watching the self-proclaimed YouTube experts talking about shims.

This topic comes up every once in a while, and you'll get a lot of conflicting answers. It's the same argument as with "what bear gun to use" or "does sorting and weighing ammo improve accuracy."

The only way to know for sure is to test yourself with the shims in and shims out. Holes in paper don't lie! YouTubers need click bait!

BTW I'm in the it doesn't improve accuracy camp! I have tested shims in three different CZ 457 rifles with no conclusive evidence shims produced tighter groups.

YMMV Good luck!

But if you shimmed a bolt to the point of zero clear between the bolt and the back of the barrel.
But still had poor qaulity machined bolt face cartridge pocket of .044" depth,?
Then NO
Your junk CZ performance wouldn't be any different before or after the shim .
Not with a optimum .041-.042" proper heads pace depth.
This is exactly what's occurring with the original posts bolt.

 

Shimming the bolt foward of the locking mechanism DOES change headspace. If the pocket is .044 then shimming can only bring the headspace to .044 but .044 may provide better accuracy then say .051. Shiming the bolt on an old worn bolt is certainly NO joke as the extra space starts to affect ignition reliability. I have shimmed bolts on old 5 teen Remingtons and both reliabilty and accuracy improved. Reliabilty improved to 100 percent and accuracy was improved as well.

 

Reliability improved. I cured a FTF problem in my Ruger 77/22 boat paddle by modestly shimming the two piece bolt. IMHO some of the firing pin's energy was being absorbed by the loose bolt. This rifle has been back to Ruger for FTF problems. Ruger techs said the 77/22 was within specs and recommended using different ammo. I can't prove increased accuracy but it does now reliably go BANG.

 

Total headspace is the combination of the distance from the bolt face to the recess in the bolt where the shell sits PLUS the distance between the bolt face and the rear end of the barrel. You measured the recess depth at 0.044", so if your bolt is kissing the barrel when you close the action, the least amount of headspace you can ever get is 0.044". You will never "shim" it to less than .044".

The big question is, do you want to shim the bolt so that it contacts the barrel? I say, NO!
Why? Because, just as soon as you get a bit of wax up or firing residue build up on the back of the barrel or bolt face, you are now in a bind and the action will be very difficult to close. Go ahead and crank it closed anyway, you'll just wear the locking lug.

What is the happy medium? I vote for .002 - .003"gap between the bolt face and barrel. If that, combined with your .044" recess gives you .046 - .047" total headspace, you still have options. First (and best) is, don't worry about it. The second option is grinding a couple thousands off your bolt face so that the total headspace is .043". You could also turn the shoulder back on the barrel so the barrel sets deeper into the action.

Of course, if your total headspace is on the high end, say 0.051", then I'd agree that bolt shims are a viable and inexpensive option. I'd still prefer to set the barrel back by turning the shoulder on the barrel and/or grinding the bolt face, but that is just me.

BTW, if you EVER run across statistically significant data that demonstrates a total headspace of .043" is more accurate than that same rifle with .046" headspace, please share it with me. I have never seen it.

 

Total headspace is the combination of the distance from the bolt face to the recess in the bolt where the shell sits PLUS the distance between the bolt face and the rear end of the barrel. You measured the recess depth at 0.044", so if your bolt is kissing the barrel when you close the action, the least amount of headspace you can ever get is 0.044". You will never "shim" it to less than .044".

Yep!

 

If your headspace is excessive bolt shims will help with more consistent ignition...less chance for cartridge jump, which could lead to maybe a bit more consistency in group sizes, better accuracy not likely. Rim thickness plus 2 or 3 thousandths is fine, shim to a hard bolt close and you'll be shimming regularly as the bolt lug wears down.

 

It does not matter how deep the case head pocket on the bolt is if one is shimming the bolt or the barrel. The pocket depth is a fixed value and only by removing material from the end of the bolt surrounding that pocket will the pocket depth be reduced. It really IS that simple.

 

I picked up some bolt shims for my Tikka, hoping to set it to the mythical optimal .043". Turning the gun upside down and using a feeler gauge thru the magazine well, I found the bolt face is contacting the barrel when the bolt is fully closed. So the only headspace I have is the recess in the bolt face. I measured that and it's .043". So I am in the place I want to be without making any changes, I have not even opened the bolt shim pack.

 

Bolt shims are not a joke if your gun shoots better with them.

 

But do they actually shoot better with them? (please don't send me the usual YouTube vids with minimal testing).

Even if a rifle appears to shoot better. Is adding and/or removing shims something you want to do to your bolt? I might do it to an old rifle with excessive headspace as a last ditch effort to get it shooting again but not sure I'd do it to a new rifle

For those who are curious what I'm referring to....read Calfee's article about shimming bolts.

 

Yep. I will first measure to see what I have(haven't been out of spec so far), and when I see that I'm within recommended spec I'll move on and begin my regular ammo testing.

 

I find it amusing that the same people who say adjusting head space with shims is a waste of time , are often the same folks that are advocating having a gunsmith set the head space at a considerable cost.