.22lr headspace ?

tell us what you have heard. I can say that excessive headspace can still be an issue, even with the miniscule .22lr.

Bad headspace = metal gets hit like by a hammer. .22LR doesn't hit as hard as most other rounds, but it still hits. Bigger dent = more smacking room = sooner or later, major problems. Often, .22 LR has so much metal that you can expect the rest of the gun to die before a CF can happen, but that doesn't mean that the action beating won't cause flaws in the operation of the gun, resulting in jamming and complete lock up of the action, among other things.
More or less, it depends on the gun. Headspacing a .22LR from my experience is quite easy, and can often be done with simple hand tools so long as you have calipers to measure with. Provided you already have your chamber drilled and all the parts in place, it only takes a few minutes to do. Better safe then sorry.

You need to check headspace when you change a bolt, because very often that will change the headspace.

Too little headspace, and the gun may fire when the bolt is closed and the rim is crushed.

As for problems caused by excess headspace in a .22 LR, well, they will most likely only be:
1. Mis-fires.
or
2. Blown case rims.

Simplest way to check it is to put on your safety glasses & leather gloves and shoot it.

If it fires every time, and doesn't blow cases, you are good to go on a plinking rifle.

If it does blow cases, or stretches the rims excessivly, you have a problem that may be difficult to correct with normal home shop tools.

Might I ask why you are changing the bolt?

rcmodel

When the bolt is closed, the distance between the back of the bolt head and the part of the barrel where the .22LR seats must be no more then 0.002 of an inch more then the thickness of the .22LR rim.
I would have to see the bolt and how the .22LR shell seats in the gun to give you complete instructions on how to headspace it, but you shouldn't have too much trouble figuring it out on your own.

Schleprok62,
Headspace on a 22 is the gap from the bolt face to the back of the chamber where the cartridge rim rests. The acceptable range of this gap is .042" to .049". Ammunition rim thickness varies from .037" to .044". if the gap is too excessive the case may not be supported and could possibly bulge or rupture. What can also happen is the firing pin may not be able to reach the case or hit it hard enough for reliable ignition if the headspace is excessive. If the headspace is too tight it may compress the rim enough to ignite the cartridge.



Please tell what rifle it is that you are replacing the bolt on. On a semi-autos the extra metal at the front of the bolt controls the headspace. On a bolt action the locking lug controls the headspace. On most .22s this locking lug may be part of the handle where it contacts the receiver. As this surface wears the headspace will increase. It can be fixed by installing shim washers between the parts of 2 piece bolts or you can weld up the worn surface where the lug bears against the receiver surface. Tight headspace can be relieved by polishing a few thousandths of metal off the bearing surfaces.

The best way to inspect headspace is with guages made for the purpose. I have found some rifles that were even .010" over maximum.

In my experience, too little headspace in a .22 is more likely to be a problem than too much. The reason is that with too little, closing the bolt rapidly can fire the round. I have seen semi-autos with too little headspace fire full auto because the rim was pinched when the bolt went forward.

Jim

2. Blown case rims.

Click to expand...

That's it! Trust me on that one! No misfires, no nothing else. Just a blast in the eye socket! Without warning! Have a look at 22lr bolt designs. How many have a gas vent or a flange at the rear of the bolt to deflect gasses?