Bolt face ID vs. Case Head OD

[ntsqd]

How tight should these fit? What is too much clearance?

Reason behind these questions, thinking of a Howa Mini rebarreled to .224 Valkyrie. If I start with a 6.5 Grendel or 7.62X39 the bolt face ID is .032" larger than the case head.
Unsafe, and if so, out of curiosity, why?
Risking it being inaccurate?
No big deal, run with it?

 

[ntsqd]

I might add that when I tried a case in the bolt that the extractor engaged significantly. Of course, I can't try it with a fired case in the chamber so.....

 

[FURMAN]

I might add that when I tried a case in the bolt that the extractor engaged significantly. Of course, I can't try it with a fired case in the chamber so.....

Are you wanting to shoot factory ammo? Most say the PPC bolt will not extract an SPC case. I would suggest a 224 AR,22 Grendel, 22PPC, or 220Beggs instead. .

 

[ntsqd]

Factory ammo to start with.

Is that in an auto-loader? Have one of those and moving away from it.

Other option would be to buy a .223 and have the bolt face opened up. Just seemed like this option might save that work.

 

[FURMAN]

Factory ammo to start with.

Is that in an auto-loader? Have one of those and moving away from it.

Other option would be to buy a .223 and have the bolt face opened up. Just seemed like this option might save that work.

If you are set on the howa mini and want to shoot factory ammo I would just go 22 Nosler.

 

[ntsqd]

I'm set on two things, Howa Mini and .224 Valkyrie. I'm thinking it will make a dandy middle weight varmint rig. Haven't yet settled on a barrel mfg. but do have a 'smith lined up to do some other work and I'll ask him to do this if all goes well.
If I could just screw the Satern Valkyrie AR bbl into the Howa I'd be nearly done.

 

[FURMAN]

I'm set on two things, Howa Mini and .224 Valkyrie. I'm thinking it will make a dandy middle weight varmint rig. Haven't yet settled on a barrel mfg. but do have a 'smith lined up to do some other work and I'll ask him to do this if all goes well.

I can't help you then. The Nosler is a better case and fits the 223 bolt face. I also would much rather have a CZ than the Howa to start with. You will have to buy the 223 and have the bolt face opened which is not worth it in my opinion. Good luck in your endeavor.

 

[ntsqd]

We'll have to agree to disagree on the Nosler case and the CZ.


So, back to the topic, maybe a better question is how much clearance is normal for the bolt face to case head? Is there some industry standard for this, or?

 

[lancetkenyon]

.224 Val is a .422" case head.
.223 Rem is a .378" case head
.473" is standard case head.

So I would get a bolt for the 6.8 SPC or .30 Rem. Or open up a .223 bolt face.

 

[J E Custom]

As a rule I like .007 to .010 more than the case head diameter.

If it is less than .007 thousandths, the case can jam in the recess as it tries to eject on some types of bolt faces.

If it is more than .010 thousandths, the extractor may slip out of the extractor grove and not completely eject clear of the action.

Ejection becomes the problem if the bolt face is to large. Accuracy is not a problem if the head space is good and sizing has not been over done.

I recommend finding a rifle with the same bolt face size or one smaller so you can open it up to the correct clearance. rebated rim cases may require a little more clearance but can be dealt with by placing a chamfer on the outer edge of the bolt face the same angle
as the back of the case body.

J E CUSTOM

 

[ntsqd]

.224 Val is a .422" case head.
.223 Rem is a .378" case head
.473" is standard case head.

So I would get a bolt for the 6.8 SPC or .30 Rem. Or open up a .223 bolt face.

The 7.62X39 case head is .446, which is only .024" bigger, but is far bigger than JE's preference. The Howa Mini, to the best of my knowledge isn't offered in either 6.8 or .30 Rem, so it would have to be the latter option, an opened up .223 bolt.

 

[Axl]

Another option is a 22 Grendel. Bolt face will work and you can neck down Lapua 6.5 Gren. brass, also probably get a few more grains case capacity.
I have a couple of the Mini's ( 222 Rem & 6.5 Grendel)

 

[J E Custom]

How tight should these fit? What is too much clearance?

Reason behind these questions, thinking of a Howa Mini rebarreled to .224 Valkyrie. If I start with a 6.5 Grendel or 7.62X39 the bolt face ID is .032" larger than the case head.
Unsafe, and if so, out of curiosity, why?
Risking it being inaccurate?
No big deal, run with it?

The 6.8 SPC case head is .422 (Same as the Valkyrie) if you can buy one it the rifle you want. other wise you will have to find it in 17 rem, 204 Ruger, 222 remington and 223 rem and open the bolt face and install a new properly sized extractor.

J E CUSTOM

 

[HobieH3]

You could get a 223 and have it rechambered and the bolt face relieved unless you're set on a custom barrel. Thought about it for my Savage 12 but not worth it in a 9 twist