Howa bolt lug not engaging

[voomdoom]

Howdy,
I got a newer Howa bolt action and I am only seeing 1 lug making at best 50% contact while the other is making no contact at all. With the right ammo i can shoot close to moa but i was hoping for better as we always do. I was thinking of lightly lapping the contact side until i saw at least some contact on the non contact side. I don't know how far out it is, but i would guess it shouldn't be too much? Does this sound like a good idea? Do you think I would see any improvement in accuracy?
Thanks

 

[spife7980]

Is it the left side/top lug thats the one making contact?

 

[voomdoom]

Is it the left side/top lug thats the one making contact?

That is correct. How did you guess? is that common?

 

[natdscott]

Do you think I would see any improvement in accuracy?

Is it the factory barrel?

If so, then no, you probably will not see much increase in accuracy.

Doesn't mean lack of contact is okay to leave alone.

 

[natdscott]

That is correct. How did you guess? is that common?

It is seen in actions with 90-degree trigger engagement.

The complete opposite is the case with Remington 700's and similar, with 30-45-degree engagement. Think about the geometry of the thing, and what that spring tension is going to do to the bolt body, and you'll understand why.

That, uh, is also why BR guys used to/still do bush the rear of the bolt body of those types of actions to make it nearly an interference fit with the rear bridge.

 

[voomdoom]

Is it the factory barrel?

If so, then no, you probably will not see much increase in accuracy.

Doesn't mean lack of contact is okay to leave alone.

Yes, stock barrel.

 

[spife7980]

That is correct. How did you guess? is that common?

When the bolt sags down on an empty chamber without tight fitting brass or the pressure during firing to hold the bolt straight back against the lugs the bottom pivots away and the top pivots back into the lug. Its normal.

 

[stello1001]

How did you test for this or determine the amount of contact?

 

[natdscott]

How did you test for this or determine the amount of contact?

I'm hoping he used layout fluid, or at least Sharpie, and chambered a round or fired brass..

 

[spife7980]

I imagine just looking at the back of the lugs where its worn through the bluing.

 

[stello1001]

I'm hoping he used layout fluid, or at least Sharpie, and chambered a round or fired brass..

This would not be the best way to determine. You can sharpie the lugs and chamber a live round all you want but not the same as when firing a live round. Another thing to note, if the ejector was on there as well with the dummy round, it will spring the bolt back unevenly.

The best way to test for this would be cut in half a piece of brass, place a large spring in it, remove firing pin and ejector from bolt, then chamber the modified case. At least this will give a much more accurate representation of lug. contact!

 

[voomdoom]

How did you test for this or determine the amount of contact?

There was blueing from factory around the lugs and after cycling the bolt a bunch and a few dozen rounds I've seen 50% blueing removed from the upper lug face while the other lug remains unmarred.

 

[natdscott]

This would not be the best way to determine. You can sharpie the lugs and chamber a live round all you want but not the same as when firing a live round. Another thing to note, if the ejector was on there as well with the dummy round, it will spring the bolt back unevenly.

The best way to test for this would be cut in half a piece of brass, place a large spring in it, remove firing pin and ejector from bolt, then chamber the modified case. At least this will give a much more accurate representation of lug. contact!

And yet, my method has worked nicely.

I will point out, though, that a piece of scotch tape on the head of the case does help.

Too: firing a live round, and letting the bolt's only lug making contact to flex enough that the other lug makes contact...well, that isn't indicative of a safe/accurate arrangement...it's just indicative that enough pressure is being exerted on the bolt face to cause ONE lug to undergo enough plastic deformation to allow t'other one to contact.

You're right. A fired casing, sawed in half, with a valve spring in the middle, is a very good way to go about this.

 

[voomdoom]

This would not be the best way to determine. You can sharpie the lugs and chamber a live round all you want but not the same as when firing a live round. Another thing to note, if the ejector was on there as well with the dummy round, it will spring the bolt back unevenly.

The best way to test for this would be cut in half a piece of brass, place a large spring in it, remove firing pin and ejector from bolt, then chamber the modified case. At least this will give a much more accurate representation of lug. contact!

I will start looking for a spring to rig something up.

And yet, my method has worked nicely.

I will point out, though, that a piece of scotch tape on the head of the case does help.

Too: firing a live round, and letting the bolt's only lug making contact to flex enough that the other lug makes contact...well, that isn't indicative of a safe/accurate arrangement...it's just indicative that enough pressure is being exerted on the bolt face to cause ONE lug to undergo enough plastic deformation to allow t'other one to contact.

You're right. A fired casing, sawed in half, with a valve spring in the middle, is a very good way to go about this.

I read of some using a wood dowel down the barrel to push on the bolt face could help get a better reading. I'm going to try a couple things to verify that it indeed is not making contact. What should I do if it isn't making contact?

 

[spife7980]

What should I do if it isn't making contact?

Probably not worry about it.

 

[voomdoom]

Probably not worry about it.

That would be tough to do.

 

[spife7980]

Sounds like you ought to pay to have it indicated and see how far out of true it really is to quell your fears and then pay them to fix it if it is even really a problem or you could have bought something thats worth more than 300 bucks to start with.

 

[voomdoom]

Sounds like you ought to pay to have it indicated and see how far out of true it really is to quell your fears and then pay them to fix it if it is even really a problem or you could have bought something thats worth more than 300 bucks to start with.

Fair enough, but I guess I'm trying to learn here what is acceptable or what to expect then out of a lower end rifle.

 

[natdscott]

I did forget to mention: if you are doing this stuff, and/or applying 220 lapping compound to the lugs, remove everything except your bolt body. No ejectors, extractors, FP assembly, etc. should be in place for these operations.

 

[Steel head]

Probably not worry about it.

Meh.
It’s not a big issue in my opinion.