L46 Bolt Design

[srma63]

From Frank de Hass "Bolt Action Rifles", I've learned that the bolt face recess for both the .22 Hornet and .222 Rem chambered rifles is .055"; and, the diameter of the recess is .352" for the .22 Hornet and .380" for the .222 Rem. I also believe that the method of operation is for the extractor to "push" the cartridge into the chamber before engaging the cartridge rim. It would seem, therefore, that a bolt designed for the .222 Rem, when operated in a .22 Hornet action, should be able to chamber a .22 Hornet cartridge, or for that matter, pass a NO-GO/GO gauge test. Granted, the rim of the cartridge/gauge might not be as firmly seated as one would expect, but then what's .074% slop going to hurt? Or am I showing a seriously lack of gunsmith savvy?
Anyway, I have an L46 in .22 Hornet but no bolt, and I have an L46 in .222 Rem with a bolt. I installed the .222 Rem bolt in the .22 Hornet action and it fit like a glove. However, when I ran the NO-GO/GO gauge tests the bolt would not close. When I opened the bolt, the gauges appeared to have not seated themselves into the bolt face recess, and the extractor seemed to be the reason why. That is, the rim of the gauge was jammed between the side of the recess and the edge of the extractor.
If there is anyone out there who knows for certain whether the extractor for a .22 Hornet and that for a .222 Rem are either the same or dissimilar, and if dissimilar, how are they dissimilar? I would really appreciate having that bit of knowledge. Furthermore, I would appreciate the group's comments with respect to the suppositions/assumptions I have posted above...but do be gentle. I promise, I will not fire anything through this rifle until I know for certain that it is OK to do so...and then I'll probably rig up a sled and a long lanyard.

 

[stonecreek]

SRMA: The rim thickness of the Hornet is listed as .065". I can't locate the rim thickness of the .222, but I am sure it is thinner. Therfore, the extractor hook on the .222 bolt is probably slightly too short to hook over the rim of a Hornet case (or gauge). This should be easily solved by removing the extractor and carefully grinding a little metal from the inside of the hook to make its reach a little longer. I suspect that the use of a .222 bolt in your Hornet L46 can be successful with just a little modification.

 

[srma63]

I expect you're right, and the rim design may also be influenced by the fact that the .22 Hornet is a semi-rimmed cartridge while the .222 Rem is rimless. The .223 Rem and 204 Ruger cartridges have rim thicknesses of .045 and .0449, respectively.

 

[stonecreek]

With the rim thicknesses you found for the other .222-headed cartridges, it looks as if your .222 extractor needs about .020" more reach. That shouldn't be at all difficult to modify simply by taking that much off of the rear face of the extractor hook. Good Luck! Sounds like you might get your fine old Hornet up and running soon.

 

[srma63]

Sounds like a plan, but I'm still concerned about one aspect to this calculus, to wit, the depth of the bolt face recess. Who am I to question the authors of "Bolt Action Rifles", but it seems odd that the bolt face recess for a .222 Rem setup would be the same as that for a a .22 Hornet (i.e., .055"), when their respective rim thicknesses are .045" and .065".
Is there anyone out there who has an L46 in .22 Hornet that also has the capability of accurately measuring (a) the depth of the recess and (b) the reach of the extractor (i.e., as measured from the tip to the rear face of the hook)? If so, would you please share that information? Thanks.

 

[srma63]

I went back and checked my 3rd Ed. "Bolt Action Rifles". It is quite clear that the bolt face recess is .055" for both the .22 Hornet and the .222 Rem. I pulled the .222 Rem bolt out, inserted the .22 Hornet GO gauge into the recess and it fit like a glove. The extractor, because the hook hits the side of the rim and, therefore, does not fully engage the rim, doesn't return flush with the bolt surface. This is probably what keeps the bolt from rotating fully into battery. How's that for a firm grasp of the obvious?

 

[stonecreek]

Your last description was what I was suspecting. If you machine/grind away enough of the rear face of the hook, then your extractor should work with a Hornet case. In more precise terms, "enough" should be the difference in .065" and .045", although a little less is probably "enough" in that there will be some + or - in the dimensions of your extractor hook as it now sits.

I'm not surprised at the bolt face recess being the same for each cartridge. It is actually not a critical dimension since the extractor fits in a cut in the rim of the recess rather than reaching over it. Remington 700 fans love the concept of "three rings of steel" supporting the case head, but actually, the deeper the bolt recess the further out of the chamber the case head extends.