22LR headspace

[MFG_BOP]

guys, sorry for the total ignorance on this round. I really looked around about the subject but didn't find anything related.

how is the headspace achieved? i mean, let's say the recess on the bolt face (for the rim/head of the ammo) has a depth of 0.043". some rounds are 0.040" of rim thickness, so you will have a gap of 0.003" between the head of the bolt and barrel face. is it fine this gap? what if the bolt has a shallower recess, lets say, 0.038"?

i meant for a bolt action.

do you also have to have a bolt face to barrel face clearance like centerfires do?

thanks for any input.

MFG

 

[linekin]

You absolutely want clearance between the bolt nose & breech. I shoot for .042-.043 when doing my own barrels. I predominantly shoot Eley Match or TenX which is pretty consistent +/- .038. Lapua rims are a tad more from what I've found.
If your bolt has a shallower gap as you described take what you want for headspace off the breech face.

Keith

 

[Roeder]

guys, sorry for the total ignorance on this round. I really looked around about the subject but didn't find anything related.

how is the headspace achieved? i mean, let's say the recess on the bolt face (for the rim/head of the ammo) has a depth of 0.043". some rounds are 0.040" of rim thickness, so you will have a gap of 0.003" between the head of the bolt and barrel face. is it fine this gap? what if the bolt has a shallower recess, lets say, 0.038"?

i meant for a bolt action.

do you also have to have a bolt face to barrel face clearance like centerfires do?

thanks for any input.

MFG

The depth of the bolt recess may not equal the total headspace clearance. Many actions have a bit of clearance between the bolt and the breech. So the bolt with .038 recess may have an additional .005 or .006 clearance. Even if the barrel is fitted to contact the bolt at lock up, it may loosen up slightly with normal wear. The way to determine an actual headspace measurement is to remove the barrel and take measurements. Headspace gages can be used to determine whether the dimension is within specs without removing the barrel.

 

[Dusty Stevens]

You absolutely want clearance between the bolt nose & breech. I shoot for .042-.043 when doing my own barrels. I predominantly shoot Eley Match or TenX which is pretty consistent +/- .038. Lapua rims are a tad more from what I've found.
If your bolt has a shallower gap as you described take what you want for headspace off the breech face.

Keith

Is a 10/22 designed to stop the bolt with the barrel or only touch the barrel when empty? With a headspace of say .043 how much clearance is there between the bolt face and barrel- (bolt actions as well)?

 

[Roeder]

Is a 10/22 designed to stop the bolt with the barrel or only touch the barrel when empty? With a headspace of say .043 how much clearance is there between the bolt face and barrel- (bolt actions as well)?

Ahh, you got me there. Semi autos do have the bolt in contact with the breech and under spring tension. If the depth of the bolt recess is less than desired headspace, a recess slightly larger than rim diameter is cut into the breech. Most standard or Bentz reamers have the counterbore as part of the reamer. Benchrest guys use reamers without the counterbore to be able to control chamber depth and bullet engraving precisely.

 

[Dusty Stevens]

Ahh, you got me there. Semi autos do have the bolt in contact with the breech and under spring tension. If the depth of the bolt recess is less than desired headspace, a recess slightly larger than rim diameter is cut into the breech. Most standard or Bentz reamers have the counterbore as part of the reamer. Benchrest guys use reamers without the counterbore to be able to control chamber depth and bullet engraving precisely.

It wasnt a gotcha on purpose, i was wondering if the rim should keep the bolt off the barrel a few thou- i was wondering that as i look at a 10-22 and see where the bolt slams the barrel if it should have clearance there?

 

[linekin]

Is a 10/22 designed to stop the bolt with the barrel or only touch the barrel when empty? With a headspace of say .043 how much clearance is there between the bolt face and barrel- (bolt actions as well)?

The op asked about bolt actions. I do not know what the semi guys are doing but would guess they don’t allow for it either. Vibrations kill accuracy as I’m sure you know.
Keith

 

[MFG_BOP]

thanks but still not sure if I understand it. please, have a look at the attached image. so, in my mind, if you have a deeper recess plus a gap between the bolt nose and breech, when the firing pin strikes the round's rim it can move forward and not shoot. am I wrong?
regards
MFG

 

[Roeder]

It wasnt a gotcha on purpose, i was wondering if the rim should keep the bolt off the barrel a few thou- i was wondering that as i look at a 10-22 and see where the bolt slams the barrel if it should have clearance there?

I don't think so, although semi auto's aren't really my area. The few I've done were headspaced to allow the bolt to fully contact the barrel with a cartridge chambered.

 

[Roeder]

thanks but still not sure if I understand it. please, have a look at the attached image. so, in my mind, if you have a deeper recess plus a gap between the bolt nose and breech, when the firing pin strikes the round's rim it can move forward and not shoot. am I wrong?
regards
MFG

The total distance between the breech and the bolt face at the bottom of the recess is the actual headspace measurement. It should be just enough to allow the action to close without pinching the rim. You are correct that excess clearance could cause misfires (or erratic ignition). With custom rimfire actions like the 2500X, the design requires no recess in the back of the barrel. Other designs have a shallower recess in the bolt thus requiring some additional counterbore in the barrel.

 

[MFG_BOP]

thanks Roeder, it does make sense now.interesting that i've never seen a barrel with a recess on the breech. anyway, things are clearer now.
regards
MFG

 

[Will Henry]

I chamber my own (bolt action) 22's to .040-.041 and am happy with the results. WH

 

[epc308]

thanks Roeder, it does make sense now.interesting that i've never seen a barrel with a recess on the breech. anyway, things are clearer now.
regards
MFG

Remington 581, 541, etc., have a recess in the breech face of the barrel with a flat face bolt.